BOSCH ECU - In need of a working unit! (0261200055)

[BimmerWalter]

Hi ,

I am in trouble as I might have destroyed the ECU of my 1985 M635CSI. If you know where I can get a working BOSCH ECU (0261200055) - plase let me know!!

Problem description: everything else seems to be working ok, starter runs but no ignition. I have not tested if the injectors are geting power.

Please help if you have a unit stored somewhere or if you know a place where I can get one.

[RSheiman]

Best bet is to call Programa and see if they can repair. More than likely they can and a hell of a lot cheaper than a new or used one.....which you won't find anyway. I did this with my US 88M6. If nothing wrong with it, they are honest, let you know and ship it back.

https://www.programainc.com/default.aspx

[DesktopDave]

I'd also recommend having it sent out for testing. Those units are quite durable, often repairable, and very difficult to find. To make things worse, there are a bunch of M635 versions, and most seem incompatible with each other.

I'm not sure what you've tested, but if I were in your shoes, I'd be very interested in what the ignition switch and start circuit are doing. I'd also be checking the main relay, coil & circuit and plug wires. Those often cause symptoms much like a bad DME.

I always wondered if you could swap a similar era DME into the car, perhaps even a Porsche or Volvo unit, as many allow chip swapping. Those 80s DMEs have a lot of similarities across the range.

[e24mpwr]

I'd also recommend having it sent out for testing. Those units are quite durable, often repairable, and very difficult to find. To make things worse, there are a bunch of M635 versions, and most seem incompatible with each other.

I'm not sure what you've tested, but if I were in your shoes, I'd be very interested in what the ignition switch and start circuit are doing. I'd also be checking the main relay, coil & circuit and plug wires. Those often cause symptoms much like a bad DME.

I always wondered if you could swap a similar era DME into the car, perhaps even a Porsche or Volvo unit, as many allow chip swapping. Those 80s DMEs have a lot of similarities across the range.

This is all solid advice/thoughts.

I didn't know there were a bunch of M635 ECU versions - first I've heard of that.

I'd send your unit to Programa.

[DesktopDave]

I didn't know there were a bunch of M635 ECU versions - first I've heard of that.

Sorry, that's unclear. Thanks for the suggested correction. I should have said there's a bunch of different S38 DMEs, I'd bet there's varying degrees of compatibility there.

[e24mpwr]

Sorry, that's unclear. Thanks for the suggested correction. I should have said there's a bunch of different S38 DMEs, I'd bet there's varying degrees of compatibility there.

I'm only aware of one version for the Euro/M88, but honestly I might have missed a nuance.

My understanding is a M88 will run on a non-055 ECU, but not well (since M88/S38 details don't map exactly) - not something you'd want to drive around. (but I could be wrong)

[RSheiman]

We need BimmerWalters thoughts on all our banter.

[Dash01]

Using a cheap soldering pen from Walmart, I've re-flowed the solder joints on several of these Bosch units, as they can develop hairline cracks. So far, this has worked just fine, every time. Just be careful to heat the work at each connection, and don't cross-flow the solder between joints. If you need a new ignition trigger, they run about $5 from DigiKey, and the newer ones are more durable than the originals.

[jbd5015]

Another vote for Programma.

They saved another members Alpina B9 recently that had gone through some strange federalization and had the wrong ECU in the car. Programma had the right ECU in stock for the car (011).

[e24mpwr]

Apparently Programa is running a special on ECU repairs ($614 vs $767)
https://www.programainc.com/item_det...ategory=39&sf=

I have an "injured" 055 that I should send to them, but $650 seems like a lot to spend and then sit on a shelf...

[RSheiman]

I always find it frustrating when the OP does not give follow-up. We try to help, we like to know that our advice is sound and that others can search these Posts and get answers and not just dead ends.

[1986series6]

Rob, +1

[DesktopDave]

I agree, it's frustrating. Regardless, I hope it's been fixed by now. Not to generalize, but our Nordic friends are impressively skilled when it comes to repairing & upgrading their vehicles. Now that I'm thinking on it, I'm as guilty as anyone else letting a troublesome issue sideline my car (should be ready this year, LOL).

All is not lost..others will find our collective wisdom (if that's what it is) when searching to resolve a similar problem.

[RSheiman]

Accuracy and answers is what makes this forum leaps and bounds above others.