SWITCHGEAR BY-PASSED

Hello everyone

I'm Alessandro and I live in Italy.
I own a Mercedes R107 SL 350 m.y. 1975 with D-Jet ; during some work in the engine bay, I discovered that the switchgear located in the left front inner fender has been disconnected ( probably because faulty or suspected so )
The car seems to start well both when cold and warm but I didn't yet test it at high rpm.
Could be that a problem or may I leave the switchgear disconnected permanently ?
I've read on some US forum that the suggestion is to replace the original points and coil with the Pertronix products.
Does exist a procedure test in order to verify if the switchgear is ok or not ?

I hope that some can help me about this matter.

Thanks in advance

Alessandro

Hi Alessandro,

welcome to jetronic.org. The switchgear should be the ignition contorl module. In MY 75 you already have the 0227051024 standard module.

Diabling and running directly via ignition contact to coil is possible. but it creates a high wear on your contacts and you have to continuously readjust dwell and timing. It would be a good idea to reinstall this module. It need not necessarily be broken. There is also a problem with availability of the green line from igntion distributor toignition module and its coax connector. Maybe that is the reason that someone omitted the module.

Hi Volker

thanks for your reply.
About the ignition control module, I checked the number I have on the car and found that it is the Bosch 0227051017
At this point, do you suggest to test it refitting the wiring as shown on the electric diagram ?
Or do you have other suggestion in order to check if the module is ok or not ?

Best regards

Alessandro

Hi Alessandro,

the 0227051017 is the earlier wheel type ignition module. It is inside the front fender outside of engine compartment. This has a different wiring than the standard module. However with a 75 350 SL you should not have the early wheel type version but the standard version. According to Bosch the standard type was used as of 7/74 Please provide your FIN so that we can cross check.

Hi volker

i assume FIN is the VIN so the number is 107 043 10 011773
The car was made on Dec 1974
Maybe the ignition module was already changed during the life of the car ?

Hi Alessandro,

now it is clear. Standard igition module was introduced awith 107043xx011888 . So your car really has wheelhouse type ignition module. It is therefore well possible that it has failed and your wiring was switched to no tranistor ignition with a contact directly driving the coil.

You can rewire to original and try whether your module works. You find testing instructions here: jetronic.org/de/107sl-wsm/107sl-wsm-cont...-107sl-ri-engc-m116D . Check 07.5-519 and 07.5-520 for wheelhouse type.

During last weeks workshop we had someone diagnose his wheelhouse module to be broken. I was ready to open it and check whether it is repairable but failed to open galvanized screws from aluminium housing. That was fortunate as later we found out that is was working without problems. There the problem was a ground contact of the green cable from ignition contact to ignition module.