Early OBC question

[wattsmonkey]

Hi there, my project car is an early '84 635 with the earlier type OBC. This worked fine until very recently, when the OBC alarm went off and the car wouldn't start - classic OBC code relay symptoms as per posts on this very forum.

By early type, I mean the ECU-sized silver box bolted to the under-dash crossmember with two big connectors: one yellow and one black.

Swapped for known-good obc from stash and car now starts fine, but OBC keypad no longer working. All fuses good, somewhat confused!

Has anyone got any experience of these early obcs?

Many thanks,

Rob

[wattsmonkey]

I think the mystery is solved: third substitute obc has brought everything back to life. All connections clean, numbers exact match, just one of those annoying things.

Cheers,

Rob

[hornhospital]

After going through similar problems with my OBC "code" function locking me out of starting the car, I bypassed the the relay. The OBC still works, but now it no longer asks for a code, and the car starts and runs (or did until the fuel pump went out...soon to be fixed)

[wattsmonkey]

Thank you Ken,

It's great to know someone else has done the same thing!

Rob