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Chapter 11 of D-Jetronic article series by Dr-DJet describes testers that were made especially for this Bosch fuel injection system


Even if I normally recommend multimeter, oscilloscope and hand vacuum pump on my test stand, I did collect a number of D-Jetronic testers just for curiosity. Originally I just bought the one or the other to use its adapter between wiring harness and ECU for my own test stand. But today I am happy that I found another solution. When doing my research for this article, I found a n interesting website about testers, that gave me some hints how to optimize my test stand. And on the other hand I have to try all my testers now and repair them if necessary.

EFAW 228: Luxury multimeter with adapter
EFAW 228: Luxury multimeter with adapter

11.1 EFAW 193 / EFAW 228 - The standard

First tester for D-Jetronic of course was developed by Bosch and had Bosch no. 0 681 101 901 and model name EFAW 193. You need additional adapter EFAW 243, to measure throttle awitch, but even then you can not measure full-load contact. On tester you select measuring "throttle switch" and on EFAW 243 you switch form "I" to "III" . This corresponds to selecting "Throttle switch I" to "Throttle switch III" on EFAW 228. In order to measure full-load contact of late D-Jetronic fuel injection systems, you would have to modify EFAW 243.

After EFAW 193 a slightly modified EFAW 228 (0 681 500 00 and follwing for German, English, Frensh and Swedish). Its switches moved from upper right to lower left and it can measure all therottle switches without an adapter, including full-load contact. EFAW 228 became the standard tester for D-Jetronic and Bosch describes its usage in every Bosch workshop manuals dedicated per car. There is no manual just for EFAW 228. I highly recommend these workshop manuals, alternatively you can read my ECU pinout in appendix B or Norbert's Prüfanleitungen. But they do not compare with the Bosch manuals.

When selecting "measuring" and "injector test", ECU will be without power. Until date of make (197)9/05 this only happens via pin 16. After that date EFAW 228 A (0 681 500 08 follwing) also switches off pin 24. At the same time power to ECU pin 16 and pin 24 were combined when the other modes "Trigger contact I" ti "IV" and "MAP sensor" were selected.

Both EFAW 193 and EFAW 228 are very simple analogue multimeters for measuring resistance and voltage, working according to voltage comparison method. It is inserted between engine wiring harness and ECU, if necessary EFAW 193 with adapter EFAW 243. This adapter and the two turn switches are the main advantage of such a device compared to a modern multimeter. You do no thave to insert multimeter tips form pin to pin, you can do it easily via turning switches. Additionally it allows to start fuel pump and start an injector spray test. Before measuring you have to adjust voltage comparator via potentiometer "∞", a contribute to measuring technologies of those years.

EFAW 228 is mostly sold without accessory manometer and I have ssen prices of more than 1000€ for it. Be careful not to buy EFAW 193 instead, it looks similiar. And if you buy EFAW 193, take care to also buy EFAW 243 adapter. If yo consider EFAW 228 too expensive, you can use a simple modern mulitmeter like Voltcraft AT-400 for less than 100€. It measure more precise and can also measure dwell and engine revolutions. I do not use EFAW 228 as it has no real possibilities to diagnose ECU, trigger contacts and MAP sensor. Bosch considered that very late and developed some intelligent testers with other electronic vendors like EFI Associates, Grundig, Kent-Moore and DIgitest. They can tell you some more facts about your devices. Lucas built a variant of EFAW 228 - named Epitest, that could measure their additional amplifier for their 12 cylinders. I believe that the limited capabilities if EFAW 228 were the major reason for missing trust by mechanics of these years towards D-Jetronic fuel injection systems.

Every workshop that wants to demonstrate D-Jetronc competence will put an EFAW 228 in a visible spot for clients to see it. If I tell you that such a workshop has once told me that they cannot use it on Mercedes-Benz as it only measures 4-cylinder engines (yes it only has 4 injecotr buttons), you know it all. Do not rely a workshop's competence just because of the presence of such a tester.

Both testers can be repaired, they are simple. But if adapter is cut off or switch B with its 14 poles time 4 layers is broken, there is no replacement

  • Bosch Tester EFAW 193 / EFAW 228

  • Simple multimeter with adapter and start button for fuel pump and injector spray.
  • Adapter EFAW 243 necessary on EFAW 193, but even then you cannot measure full-load contact
  • No real diagnosis of ECU, trigger points and MAP sensor (MPS)
  • Presence of it in a workshop does not mean D-Jetronic competence
  • Deeper diagnosis only with oscilloscope or intelligent testers like VW 1218, Bosch KD-JED 7000 series, EFI Associates
  • But can measure temperature sensors at any temperature


11.2 VW 1218 - 1st intelligent tester

Green Okay, continue with next step
Yellow Wait for an action
Red Fault in step, must be cleared first

Volkswagen were the first to notice this weakness and they asked Grundig to build a tester (VW Nr. ASE 000 050) for them that would test VW and Porsche engines via typical red-light colours. You do not need to read any values, just watch those 3 lights. A real test for mechanics without any understanding of electonic issues! Actually I had once bought it ti use the adpater for my test stand. Then I found another solution and only now I have rediscovered it for this article. Meaning of colours is described in the table here.

Before starting you need to adjust this tester for your altitude, so that it uses proper values as reference. Otherwise you just turn form step 1 to step 14 and watch the lights. If there is a dot besides step number on turn switch, then you can do additional tests by pressing green button. Besides an easier reading this tester also seems to verify most of an ECUs function block in steps 4 to 11. As I have partially not yet verified what exactly it measures, I quote Brad's info in italic. This is true for steps 5 and 6. MAP sensor is only roughly tested without applying any vacuum. So it wil not recognize broken diaphragms or vacuum leakage. I repeat that you have to adjust this tester to your altitude before you start. Please remember that Volkswagen has started with absolute pressure switches, continued with type 2 diaphragm containing MAP sensors and ended up with full-load contacts in throttle switch. That is why you have to properly select year of make for VW type 3 and type 4. For Porsche select type 4. As year of make is not really enough to set this switch right, I have added the correct switch position to each Volkswagen and Porsche ECU in the list of ECUs. So best is to read the ECU number and set this switch accordingly.

Test steps in detail are as follows:

Schalter-stellungPrüfung vonzu tätigende Aktion bei Signalfarbeokay bei SignalFehler bei SignalFehlerursacheReparatur
  Preparation Remove pin 1 on ignition coil        
1 Power supply   green no signal no power present Connector not properly seated, relais injection broken, loose wire
Battery voltage   red voltage below 10,7V (minimum 11,5V recommended) Check battery voltage, wires and ground connection
Injectors   red and green Injector broken, wire or connector broken, ground contact corroded

Test in switch position 3, which injector does not vibrate. Then verify proper seating of connector there and test again:

stays red & green   →  Remove connector from injector and shortcut it
stays red & green   →  Find wire fault
turns green             →  replace injector

2 Temperature sensor I air   green red Temperature sensor I, wire or connector broken

Test proper seating of connector

stays red  →  Remove connector and shortcut it
stays red  →  Find wire fault
turns green →  Replace temperature sensor

Temperature sensor II engine   red and green blinking Temperature sensor II, wire or connector broken
2 Additional test with cold engine (20°C) if necessary
Resistance curve temperature sensors
greene Taste drücken green yellow Temperaturfühler I defekt Temperaturfühler I Luft weicht ab, tauschen
yellow blinkend Temperaturfühler II defekt Temperaturfühler II Motor weicht ab, tauschen
3 Driver test injectors   green red Driver in ECU is broken, shortcut in wires or connector

Feel which injector does not vibrate. Remove its connector and press green button on tester

turns green   →  replace injector
again red      →  replace ECU
still red         →  Remove wire shortcut and reinstall old ECU

Speed correction and fule pump control at 400/min
  green red ECU broken replace ECU
Basic compensation (rich)
  green red ECU broken replace ECU
5 Additional test if bad exhaust values
Fine test Basic compensation (rich)
press green button green red ECU broken replace ECU
Basic compensation (lean)
  green red ECU broken replace ECU
6 Additional test if bad exhaust values
Fine test Basic compensation (lean)
press green button green red ECU broken replace ECU

Speed compensation at 4000/min, full-load enrichment

  green red ECU broken replace ECU
Acceleration enrichment
  green red ECU broken replace ECU
Start and warm-run enrichment
  green red ECU broken replace ECU
10 ECU
Fuel pump activated while starting
  green red ECU broken replace ECU
11 ECU
Fuel pump shut off with stalling engine
  green red ECU broken replace ECU
12 MAP sensor   green red MAP sensor or wires broken Check wires and connector, replace MAP sensor if necessary
12 Additional test if bad exhaust values
fine test MAP sensor
press green button green red MAP sensor action in full-load Replace MAP sensor for  a try and redo test. If fault stays you either have unusual air pressure and MAP sensor is okay.
13 MAP sensor   green red MAP sensor or wires broken Check wires and connector, replace MAP sensor if necessary
14 Starter signal   yellow before starting: yellow and red Wire from starter broken Check wires and connectors from starter to ECU
Trigger points (contacts) and wires yellow
Turn starter for 5 seconds, afterwards do not switch off ignition!
after starting: green after starting: yellow Trigger contacts or wires from T.C. to ECU broken while starting yellow and red:
Check wires, clean trigger points and replace if necessary
while starting only yellow:
shortcut in wire from connector 50 on starter
15 Absolute pressure switch (until model year 69)   green yellow Wire interrupted or contact failure Check wires and connector, replace pressure switch if necessary
Segmented contacts in throttle switch (as of model year 70) yellow
Slowly push gas down completely
Change yellow - green no change yellow - green Wire. connector and function of accelerator contacts (pin 9 plus supply 12/14) Check wires and connector for interrupt and shortcut, clean or replace throttle switch if necessary.

all type 3 cars up to model year 71:
Over-run cut off
All tyüe 3 and type 4 and Porsche 914 as of model year 72: idle-run contact

green: Open throttle fully
Watch hint †1
Change green - yellow no changegreen - yellow Wire or throttle switch failure Adjust throttle switch, chck wires and connectors, replace throttle switch if necessary
all type 3 cars as of model year 72: full-load contact
Watch hint †2
green: Open throttle fully Change green - yellow - green no change green - yellow - green
Fuel pump relais green: Push button on tester
Watch hint †1
stays green becomes yellow Fuel pump relais with wires and pump Check fuel pump relais, wires and ground contacts
Fuel pump green: Push button on tester Fuel pump runs (acoustic) Fuel pump does not run Kraftstoffpumpe mit Leitungen Check fuel pump with wires, connectors and ground contacts, replace pump if necessary


Hint †1 On type 4 and Porsche 914 cars with automatic gear box after model year 71, first push back rod of speed controller so that throttle rests in idle position.
Hint †2 On type 3 cars with automatic gear box built for California after model year 72, you have to additionally test exhaust gases recirculation in step 16. For that you need to ensure that:
  • Engine temperature is above +18°C
  • Throttle switch functions verified before
When pushing down gas, you must hear exhaust gases recirculation relais in engine compartment fron right click twice.


You cannot use it to test other cars than VW or Porsche in detail with this tester. Turn switch postions X and Y were however foreseen for that. But Pin 13 is fixed to ground (air temperature sensor on VW) and pin2 is not connected at all. Pin 24 is not connected to ECU, power supply must come from pin 16 from wiring harness and wires seem very thin for that. Also wires to injectors pin 3,4,5,6 seem thin. Pin 20 does not arrive at tester, it is directly connected through in adapter.

  • VW Tester 1218 / Grundig ASE 000 050

  • Suitable for non-electricians, measuring via red-light colours and automatically.
  • ECU, trigger points and temperature sensors can be verified in detail.
  • MAP sensor (MPS) only rough test, no vacuum applied
  • Use for VW Typ 3, Typ 4 und Porsche 914 in car
  • No injector spray test.
  • Wires for power supply and injectors seem very thin
  • No test for 2nd acceleration contacts (20), also no test for 10 pulses on acceleration contact 1.
  • No test for idle-run CO adjustment
  • No test for over-run shutoff


Lucas Epitest Tester
Lucas Epitest Tester

11.3 Lucas Epitest for Jaguar 12-cylinder

Jaguar had asked Lucas to extend Bosch D-Jetronic fuel injection system for 12 cylinder engines. Lucas therfore developed D-Jetronic further for 12 cylinder engines. Later they developed their own digital System-P with a 35 pin conector. When Lucas enhanced the D-Jetronic amongst others system they added 2 components that original D-Jetronic never had:

  • External amplifier with power resistors grouping 12 injectors in 2 groups driven by 4 power transistors (see Appendix B Pinout Jaguar)
  • First 2 reed relais and later 2 hall sensors replacing original trigger points

At first glance Lucas Epitest looks like a normal EFAW 228 tester. Then you notice aditional cables for later digital ECUs and the external amplifier and a polarity switch. But alo here we have no diagosis of ECU or MAP sensor. It shows as little intelligence as EFAW 228. There is an additional adapter "Closed control loop" for system P that I do not have. Using it for testing D-Jetronic is well described in the blue Jaguar booklet "Electronic fuel injection - Provisional Repair Operation Manual". I recommend it as a tester manual. Lucas has also published a file of dodcuments that I unformatunately don't have. I would appreciate this Lucas manual of this tester. So if anyone has a copy, I'd appreciate. This should also describe testing Digital-P.

So what is really different from EFAW 228?

  • SwitchI in position Switch II, Switch II in position Amplifier, press button 2 and button 3: Exit pins 4 and 5 do not link to injectors but to the amplifier. So you will measure the resistors in amplifier with 7,5 Ω (tolerance 6-12 Omega;) versus ground. Pins 3 and 6 of ECU are not connected.
  • Switch I in position Volts 3 measures power voltage in amplifier (11-12,5 V)
  • Switch I in position Injector, press button Injector Switch 1 - 4 measures resistance of injectors per power transistor driving them. I.e. 0,8 Ω with 3 injectors connected, 2,4 Ω when you disconnect 2.
  • Switch I in position Fuel check 1, press button Injector Switch 1 - 4 activates 3 inecjtors to do a spray and leakage test. Before that build up fule pressure by pressing button "Pump". If desired, remove electrical connectors on 2 injectors ot measure just one.
  • Switch I in position Run Engine, to measure MAP sensor leakage. This test was new to me and is actually the same as I always propose to do test via a hand vacuum pump. In this position you run the engine at 3000 to 4000 rpm, then suddenly close the throttle valve and the hose to the MAP sensor. In fact you then pull a vacuum of 400 mmHg (0,5 Bar) on the MAP sensor and watch how quickly it will fall. If you are not successful, Jaguar recommends the manual pump test as I always recommend it.
  • Switch I in position Pressure Signal measures the voltage on MAP sensor with 2-4 and 12-14 V. This is only good for seeing whether your MAP sensor still moves mechanically. It is not a real MAP sensor verification.

You will find everything else in the blue Jaguar booklet "Electronic fuel injection - Preliminary Repair Operation Manual". It describes same tests as you would normally do with EFAW 228. You could also use the EFAW 228 on Jaguar. But measuring injectors would not be possible.


  Lucas Epitest

  • Like EFAW 228, extended to measure amplifier and later also Lucas Digitl-P
  • Simple mulitmeter with adapter and start button for fuel pump and spraing injectors
  • Verification of ECU, amplifier and trigger board not really available
  • If it is present in a Jaguar workshop it doese not mean D-Jetronic competence
  • Deeper measuring only possible with oscilloscope or testers like VW 1218, Bosch KD-JED 7000 Serie, EFI Associates
  • But it can measure temperature sensors well
  • It is the only tester that can enable injector spray and leakage test on Jaguar
  • Cannot test EGR control unit on USA/CAN XJ12 and XJ-S
  • Cannot verify over-run switchoff in latest ECU

Bosch KD-JE 7400 Tester
Bosch KD-JE 7400 Tester

11.4 Bosch Tester KD-JE 7400 and KD-JE 7401 for Bosch services

Also Bosch noticed that a measurement with EFAW 228 was not enough and developed its heavy instuments KD-JE 7400 and KD-JE 7401 for its Bosch servie points. I was hinted on this tester by a fromer Bosch service technician. Also Bosch Classic Service Centers like Koller & Schwemmer and others test client's ECUs with this tester. It came with additional MAP sensor tester KD-JE 7401 and vacuum socket KD-JE 7402. As I now finally was able to buy such a KDJE 7400 and KDJE 7401 without coding plugs, manual and vacuum socket KD-JE 7402 and from another source I got overview documentation of this device, I know how it is supposed to work. Coding plugs adapt it to each ECUs pinout. You can set fixed or variable speed and fixed values for both temperature sensors. Inside the tester you have internal MAP sensor coils and 8 injectors for simulation. PCB boards are of a simliar make as the ECU PCB boards. Switches allow to select various operating conditions. Additionally you can connect an external MAP sensor. These testers have no model no printed on them and I guess that they have originally been deveoped for manufacturing. They serve to verify all Bosch and Lucas ECus.

Accompanying KDJE 7401 is a device with 2 pumps and valves. Together with vacuum sockets KDJE 7402 the allow to connect a MAP sensor to simulate enviromental and manifold pressure. It is astonishing that these pumps still work after more than 40 years. As I understood from my discussions with ex Bosch people, MAP sensors were only tested indirectly via a reference ECU and at very few refrence pressure points. I consider this a very rough way of testing a MAP sensor. Firstly tolerances of MAP sensor and ECU add up and secondly just 3 pressure points are no tenough to verify slopes, full-load transition and full-load stop. I will for sure stick to my direct way of measuring MAP sensors on my test stand where I verify the whole curve and adjust it properly if necessary. I heard from ex Bosch people that they also only used KDJE 7401 to verify whether a MAP sensor would be leaking and either throw it away or reuse it.

When P. B. Anders talks of EFI 9100 as the hydrogen bomb of D-Jetronic testers, I can only praise KDJE 7400 / 7401 / 7402 above that. As I do not like bombs, I call it the Apollo rocktet under the D-JEtronic testers. It is not meant for operating inside a running car, that's what you should have a EFAW 228 for.

  • Bosch KD-JE 7400

  • Only sold to Bosch service points for testing ECUs and MAP sensors.
  • There are coding plugs for each car, to dapt to pinout of each ECU.
  • Engine revolutions can be freely simulated.
  • Simulated temperature sensor values in various steps.
  • MAP sensors can be simulated in part-load and full-load
  • Separate tester for MAP sesnors KDJE 7401 and 7402. However measuring MAP sensors is very rough.
  • All function blocks are tested and a hint for possible failures is given. However Bosch service points did norrmally not do the repair.
  • There are 2 files with documentation. Without it KD-JED 7400 is not really valuable.
  • All pins can also be monitored via oscillscope or multimeter.
  • Very big and heavy device


If you know something about this device or have this documentation, please let me know. Otherwise I have to measure every single detail by myself.

11.5 Bosch KD-JED 7500

Bosch KD-JED 7500 Tester
Bosch KD-JED 7500 Tester

Bosch later also developed a tester specifically targeted for Mercedes-Benz workshops. Mine has a few problems that I still need to repair. It is already built with ICs and is kind of an easier and condensed package of KDJE 7400 and KDJE 7401. Despite of its size and weight it is meant ot be used in cars. It simulates all sensors and verifies all function blocks. You can read injector opening times directly on a display in milliseconds. If you have reference values, you can verify ECU alone and the combination of MAP sensor and ECU. You can also measure while running the car on the street. Tester even has a manometer for ambient air pressure and a vacuum pump for evacuating MAP sensor. In some narrow sense it can also find out cable problems. As you cannot adjust speed and temperature sensor values, it has a preprogrammed setup for MB only. You can also not adapt to other ECU's pinout. It's advantage is its much easier handling and operation than KDJE 7400. That's why I consider it a good device for workshops.

  • Bosch KD-JED 7500

  • Only electrician can deal with it.
  • ECU, trigger points and throttle switch can be thoroughly tested.
  • MAP sensor can be tested in combination with ECU.
  • Only suitable / destined for Mercedes-Benz cars.
  • No fuel pump or injector spry test, no temperature sensor test.
  • An oscilloscope can be directly connected
  • Big and heavy.


11.6 EFI Associates

In the US EFI Associates developed testers like EIF 9100, that is said to even allow MAP sensor calibration. Unfortunately I could not get hold of such a device so far. So far I can only refer to Brads website.If you own an EFI 9100, please contact me.

It seems that this tester was only used in the US market where Bosch's KDJE 7400 and KD-JED 7500 were not available. You can set speeds and simulates MAP sensor coils and allows simulation of operationg conditions in car. There is no vacuum pump.

11.7 Kent Moore 112D

Kent Moore 112 D Tester
Kent Moore 112 D Tester
Kent Moore 112 D Bedientafel
Kent Moore 112 D Bedientafel

Kent-Moore Tester 112D was sold in America and principally is just a multimeter like EFAW 228 for measuring sensors. But you cannot connect ECU to it. So you cannot do a basic rough test of injector drivers. However it has has sepcialties: It can verify MAP sensors and it can let an engine run by manually adjusting mixture via a rheostat.

For verification of a MAP sensor it will be connected on atmospheric pressure and then display is adjusted to 0 inHg. After that you pull a vacuum of 15 inHg (0.5 Bar). Now you read 112D's display and it shall be positioned at its 15 inHg poistion. This method is VERY ROUGH and negates that all MAP sensors have different calibration. It also ignores environmental pressure on type 3 MAP sensors. Please do not use this method for calbration of a MAP sensor. It would however show if a MAP sensor is leaking or has a broken diaphragm. Not more than that.

I find it intersting, to control injectors via a rheostat. It means that all injectors will inject at the same time. One could hold the engine on a given rpm and then control mixture. This method does not react to changing rpm or sensor values. That is what can only be done by ECU.


Switch positionTestWhat and how will be tested?
  OFF 112D is OFF in this position.
tranparent METER ZERO Calibrate display to position needle on 0
orange BATTERY VOLTAGE Red LED must light up and voltage must be in orange range 11-13V. When cranking engine now needle must not drop below 9V
green Injectors A, B, C, D If one injector is connected, instrument shall read green 1, for 2 injectors grren 2. Exact number of injectors are listed in appendix B of my D-Jetronic compendium. A means pin 3 on ECU connector, D means pin 6.(Notes 1 and 2)
gelb Tempersture sensor I (Air) Reading should now be in yellow range. Dotted range stands for 40°C to 80°C.
braun Temperature sensor II (Engine) For warm water cooled engines display needle shall be in hatched brown area (normally 80°C). Air cooled engines shall postion needle anywhere in brown range (normally 110°C)
Half segment '68 - '69 idle-run contactkontakt [[TS]] Needle shall move from CLOSED (bk) to OPEN (empty) when you push gas pedal by 4°.
Half segment '68 - '69 Full-load pressure switch Needle shall move from CLOSED (bk) to OPEN (empty) when you apply a vacuum of 20 to 70 mBar. After releasing vacuum needle must move back to CLOSED (bk).
Hatched '70 Acceleration contact I Needle shall swing 9 to 10 times from OPEN (empty) to CLOSED (bk) when you push down gas pedal slowly.
Hatched '70 Acceleration contact II as before.
Half segment '70 idle-run contact [[TS]] Needle shall swing gtom CLOSED (bk) to OPEN (empty) when gas pedal opens by more than 4°.
Half segment Full-load contact [[TS]] Needle shall swing from OPEN (empty) to CLOSED (bk) when you push down gas pedal completely.
blue Trigger contact I Cylinder switch in position 4 or 6 and TC switch to GROUP 1. Now press start button. Needle shall swing between OPEN (empty) and CLOSED (bk).
blue Trigger contact II Set switch for TC to GROUP 1I, otherwise as before.
blue Trigger contact III (only 8-cyl) Set switch for cylinders to 8, TC to GROUP 1, otherwise as before.
blue Trigger contact IV (only 8-cyl) Set switch for cylinders to 8, TC to GROUP 2, otherwise as before.
rot Pressure sensor Set switch PRESSURE SENSOR to "Calibrate" and turn know "PRESSURE SENSOR CALIBRATE" until 0 inHg are displayed in red sector on display top. Now switch to OPERATE. Now needle shall hardly move. If necessary recalibrate. Now pull a vacuum of 15 inHg (0.5 Bar) on pressure sensor. Needle shall now be in 15 in Hg position on red scale. Repeat to verify that needls always goes to same position.
---- Injector test Set switch FUEL PUMP on and off again. Pressure shall now increase to 2.0 to 2.1 Bar and can drop to 1.5 Bar after switching off pump. Now press NJECTOR FLOW button A and note pressure decrease. Repeat the same for B, C and D. Pressure decrease shall be the same on all 4 groups.
white RUN and Dwell

RUN - Remove vacuum hose from MAP sensor and turn knob to "MIXTURE ADJUST" to "COLD START" on cold engine or to "START" on warm engine. Set FUEL PUMP switch to "ON" and press START button. Now optimize engine run by "MIXTURE ADJUST". Depressing gas pedal a little helps to start engine.

DWELL - On running engine turn switch "TRIGGER POINTS" from "GROUP I" to "GROUP II". Displayed value shall hardly change.

  External Voltmeter Connect an external Multimeter in mode Voltage 0-20 V DC to plugs "External METER".
  Externe Resistance measurement (Ohmmeter) Switch external Multimeter to reesistance measurement and connect to plugs "External METER".



  1. Paired injectors (see Appendix B Pin 3, 4, 5, 6 on your ECU) on 6 and 8-cylinder engines will shaow a 2 in green sector. To test them one by one, remove one of the injectors from wiring harness and measure the other injector. Repeat by swapping injector connectors.
  2. Exact measurement of values in green sector are not critical and vary a bit by car manufacturer. Only values outside of green sector hint a problem.
  3. Always clean connector contacts and ensure that they jold tight and are not bent.
  4. Always switch OFF ignition when connecting or removing tester. For longer test remove pin 15 on ignition coil to avoid damage on coil.
  5. Best results can be seen when you test engine on normal or slightly above normal engine temperatures.

11.8 Ditron 812E

Ditron 812 E Tester
Ditron 812 E Tester

Ditron 812E tester is more or less the same as Kent Moore 112 D.

11.9 Self made tester

My most important tester: Hameg 1005 4-channel oscilloscope
My most important tester: Hameg 1005 4-channel oscilloscope

If you have a spare ECU and wiring harness, you can build your own tester. It is important that you connect all 25 pins to a multimeter and / or an oscilloscope. I have de-soldered a connector from an old ECU and forced it together with a wiring harness connector onto a 5.08 mm PCB board. Then I have connected all pins to connectors allowing to easily connect my oscilloscope or multimeter. This allows me to measure in a car without having to search correct pins in narrow locations around ECU in car.

For my test stand I use a similar solution together with a function generator, switchable resistors and inductance to simulate environments for verifying ECU function blocks. I read injector timing from my 4 channel oscilloscope. It does not need high bandwidth, but 4 channel are of advantage. I test MAP sensors with my own Wheatstone bridge and evacuate them with a hand pump.

  • Self-made Tester

  • Effort for building one
  • Measuring only for hobbyists with experience, you need a test plan next to you.
  • Multimeter and 4-channel oscilloscope necessary
  • Exact test of trigger points and throttle switch is possible.
  • Complete testing of ECU if yu have reference values and can simulate environment
  • You can use it on any car


My next project will be the automation of my test stand. I need a long, dark and cold winter for that, allowing me to work only on this.

11.10 Summary

D-Jetronic fuel injection system is neither nuclear science nor magic, it is a simple system. Only ECU and MAP sensor are a bit complex. But please do not start to doubt their performance before you checked all prerequisites. D-Jetronic is really very reliable and I am always surprised how reliable a more than 40 years old electronic can be. All you need for testing is a multimeter, a manometer and systematic approach. That will let you find 90% of all faults on your own. And if you really have a failure in ECU or MAP sensor, you still have me or Bosch Classic Centre.


WIshing you succesful fault finding, Your Dr-DJet (Volker)

Copyright © 2015 of this article and its content by Dr-DJet. Please post questions in forums and not via email or PM. I exclude all liabilities except those not excludable by law.