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Garage => Mechanicals => Topic started by: chinny4290 on 16 May 2016, 10:00 PM

Title: '74 D-JET 450SEL Not Running - Narrowed down to ECU
Post by: chinny4290 on 16 May 2016, 10:00 PM
Hi guys!

Boy, it's been quite a long since I've been here...but I had to put all my W116 efforts aside to take care of some life things, but I am BACK! No longer with a 280S to worry about, but a 1974 450SEL D-Jet!

So I just brought her home and my friend who is an ASE Certified Mechanic helped me trouble shoot everything. We found that everything was in great working order, voltage and OHMs included, at everything EXCEPT the ECU.

I'm thinking the ECU got shorted from the lovely and typical windshield drain hole since the ECU for US-Spec cars sits in the passenger footwell of the car, right where water leaks with that hole. The hole is fixed after the car was repainted down to the metal so the leak is a non-issue. But the ECU is still an issue.

My mechanic found that the ECU is receiving everything it needs to, but it does not send the necessary power pulse (or something along these lines) so basically, it's been narrowed down to the ECU.

I have another friend who's father is a retired Lockheed-Martin Electrical Engineer of many years and can fix pretty much anything with a circuit board. Is there any documentation on the ECUs itself that he can use if I call him to fix my ECU? It's way better I've read than buying a rebuilt unit and much cheaper, or trying to source a used one and gambling on that.

Look forward to hearing the responses guys! And attached is a pic of the car during transit :)
Title: Re: '74 D-JET 450SEL Not Running - Narrowed down to ECU
Post by: ptashek on 17 May 2016, 05:00 AM
I've stumbled upon this once, when searching for old schematics related to our Benzes: http://members.rennlist.com/pbanders/ecu.htm
It's Porsche specific I think, but the Bosch unit used by MB was probably not much different.
Title: Re: '74 D-JET 450SEL Not Running - Narrowed down to ECU
Post by: marku on 17 May 2016, 01:51 PM
If its any help I have a MB manual on the D-jet as a pdf if you want a copy send me a PM with an email. Also Bosch have re-issued their manual on the D-jet its printed from old microfiche so not a first rate image but is really worth having with a full schematic layout, wiring diagrams etc and troubleshooting. Last time I looked it was Euro29 on partbob.com.
Title: Re: '74 D-JET 450SEL Not Running - Narrowed down to ECU
Post by: chinny4290 on 17 May 2016, 07:39 PM
Quote from: ptashek on 17 May 2016, 05:00 AM
I've stumbled upon this once, when searching for old schematics related to our Benzes: http://members.rennlist.com/pbanders/ecu.htm
It's Porsche specific I think, but the Bosch unit used by MB was probably not much different.

I looked into that but I also found another source here that says the Porsche units are totally different to the Merc units, especially the V8 ones. Which makes sense, fuel delivery for a V8 is much different for a flat four or six.


Quote from: marku on 17 May 2016, 01:51 PM
If its any help I have a MB manual on the D-jet as a pdf if you want a copy send me a PM with an email. Also Bosch have re-issued their manual on the D-jet its printed from old microfiche so not a first rate image but is really worth having with a full schematic layout, wiring diagrams etc and troubleshooting. Last time I looked it was Euro29 on partbob.com.

PM sent! :)

The PartBob.com site however is not responding, anywhere else I can look into that?
Title: Re: '74 D-JET 450SEL Not Running - Narrowed down to ECU
Post by: marku on 19 May 2016, 12:49 PM
Seems OK unfortunately they are showing it only in German. They do have them in English but you have to keep looking. Got your PM manuals sent. Hope they are useful.

http://www.partbob.com/workshop-literature/d-jetronic/kundendienstanleitung-bosch-d-jetronic-in-mercedes-benz-r107-w107-w114-8-w116.html