Measure Map sensor

Hello
Wondering if anyone knows what's wrong?
When I measure the map sensor between pins 7 and 15, it shows exactly 90 ohms
and between pins 8-10 330 ohm, it is within tolerance.
But when I measure the resistance between pins 7-11, 8-11, 10-11, 15-11, it's zero even when i remove the contact on the map sensor.
If I have understood correctly, should there be resistance, ground fault?
So what should I do, thankful if anyone knows.
The car is an Mercedes 250 ce

Hi whizz (you didn't tell us your real name, it would be easier and more personal you would do this...),
I must admit I never measured the resistance from to MAP sensor-connector towards the ECU - because this doesn't make sense.

Please pull off the connector from the ECU and you can measure there at the connector.
You could use the plan you find here: jetronic.org/de/forum/jetronic/19-messpl...ents-by-car-model#68
(Instruction on top of that page).

The MAP-sensor normally doesn't go defective in the coils-unit but it gets vacuum-leaky.
Look at Volker's compendium how to test it: jetronic.org/en/d-jetronic/mps .
For a first test you can simply try to pull vaccum by mouth - sensor will be defective if this fails.

Regards
Norbert

Hi,

that reads as if your wiring harness has an isolation problem. Normally you should have infinite resistance to pin 11.

Hello
It is through the contact with ECU I have measured.
And according to a book that Mercedes released -69 that deals with everything about D-Jetronic, there should be resistance according to that book on pins 7-11, 8-11, 10-11, and 15-11
But have read more now.
If there is still no resistance when unplugging the map sensor, there may be a ground flash over the cables 7,8,10 or 15.
Just like you say Volker, so i have to check the wiring harness

Forgive me, my name is Görgen and is from Sweden

Hi Görgen,
maybe you misunderstood the instructions - therefor:
Does your digital multimeter read '1' or '0' when you measure the pins against ground (11)?

'1' in Ohmmeter function would mean 'no continuity' and would be o.k. when measuring without the MAP sensor connected.
'0' in Ohmmeter would mean 'short circuit to ground' as Volker wrote and you believe in, too.
Switched to Voltmeter function, the instrument will only show the '0'-reading.

I ask this because I want to hinder you from stripping the harness without reason... can't believe all those four wires are short-circuited.

Regards and best wishes to Sweden
Norbert

Haha, me and electronics
It was 1 on the Ohm meter, checked again.
So that should be ok then.
But my big problem is that it gets far too much fuel.
Bought the car for about a month ago, had not been driven at 27 years.
had been standing because it worked badly.
The first thing I did was to replace the fuel lines and pump.
Then I discovered that the distributor was from a Mercedes 280 so I replaced it with an electronic 123 distributor from Holland.
Tried to start and it started immediately and worked really well at first, but soon realized that it got too much fuel, very much so it stopped.
Took away the fuel injectors today to see if they were ok, and all worked as they should, BUT 4 of them were replaced by fuel injectors, probably from the same car the distributor came from. has model number: 0 280 150 014
Are these far too big and cause it to get too much fuel?

Görgen