Early vs Late Model Cruise control

[EVillalonRN]

So, I broke my early model cruise control stalk and bought a replacement here on r3v. Turns out the new one belonged to a late model car. Little did I know that there was a change from early to late model. The early model was a 4 function stalk, Off, Resume, Accelerate, Set Speed. The Late Model has 5 functions, Off, Resume, Accelerate, Decelerate, Set Speed. Early model has 4 wires, Late Model has 5 wires. I looked at it and thought "Damn it BMW, why do you have to change things between years!!" Anyway, I took a look at the wiring circuits on the ETM for both. Turns out the wiring in the plugs are in the same order with the only difference being the additional decelerate circuit. I was able to plug my early model 4 wire CC harness directly to the late model 5 wire CC stalk by offsetting it so that the Decel wire is left unconnected. It works as before.

[robrez]

What color is the decelerate wire, so I know which way to offset it?

Is it safe to assume that the brains are specific to early and late models? Or if I plug a late model stalk into a late model harness into a early model brain will the decelerate function work?

[EVillalonRN]

It is the Blue/Yellow wire. Leave that one disconnected.
The power supply for the early harness is Green/white. The power supply for late model stalk is Violet/white. The rest match up in the approriate order. If in doubt, check the ETM
1987: http://www.armchair.mb.ca/~dave/BMW/e30/e30_87.pdf
1989: http://www.armchair.mb.ca/~dave/BMW/e30/e30_89.pdf

Did you run into the same problem as I did?

I don't think that using a late model stalk/harness into an early model would enable the decelerate function.

[EVillalonRN]

Now that I'm looking at it, the control module is the same part number for those two years. 65711386189, so you might be able to enable the decelerate if you get a late model stalk/harness.

[robrez]

Thanks, I noticed that realoem lists the same part number for early or late model brains. I'm planning to do a retrofit and I have a late model stalk and wiring harness, but an early model brain. Hopefully decelerate is enabled in the early model brain.

I also have an early model wiring harness, which was why I was wondering about the offset. But hopefully everything will work with the late model harness and stalk and early model module