R107 450 D Jetronic ECU Removal

[szamik]

Hello

I need some help

Can you tell me, where is located and how to remove Djet ECU unit in R107?

Thanks for any advice

[fonzi]

Above the passenger foot well on the firewall, up high where it shouldn't get wet even if there's water on the floor

I think there might be a screw (or multiple?) that hold on the very long pin connector.

Why are you removing it? It's very rare for them to go bad.

[szamik]

Thanks a lot.

This car wasn't running since 5 years and now I want to rebuild engine harness, because is in terrible condition so I have to disconnect it of ECU And probably I check bad solder points inside ECU.

Do you have maybe some wiring diagrams of harnesses which are under hood?

[fonzi]

There's a guy "cushjbc" who I know from Benzworld who rebuilds these as a hobby and has done some write ups on it. I think he generally saves the codes and just replaces the end connectors. I don't have a wiring diagram and wouldn't take on the adventure of making one myself. Maybe I would replace the ends though. I already have some spares for my w108 d-jet cars. And it seems my 1972 350sl 4-Speed has a good harness. If it ain't broke...

[Graham]

Originally Posted by szamik

Hello

I need some help

Can you tell me, where is located and how to remove Djet ECU unit in R107?

Thanks for any advice

It is where Fonzi said.

First unclip the plastic rivets and remove the cardboard cover under the dash. If you look up in there, you will see the ECU - Fairly large rectangular box. It has a spring clip that holds it in place along with three pins that just push into rubber grommets. Once clip is undone pull out horizontally at bottom and down. Can't recall for sure, but there may be a screw that needs to be removed to disconnect the harness plug. But there is enough slack to get at that. There is a second plug on end of harness that needs to be removed in order to remove the harness. There is a large grommet in the firewall which when removed, will just allow the ECU plug to pass through.

I rebuilt my harness last winter (with help from cushjbc on Benzworld) We learned a lot. These threads cover most of the subject:

D-Jet Engine Harness - Mercedes-Benz Forum

Winter/Spring Djet project - Mercedes-Benz Forum

We found a good source of the end rubber boots from a guy in Germany repro-parts.de. He also has the original type terminals and housings, but cushjbc introduced me to the modern double cantilever type used on Audis etc and I used those. The sleeve material from Wirecare works well and makes it easy to splice new wires to the main core of the existing harness.