anyone happen to know which pin on the obd2 siemens dme is road speed?

[flyboyx]

man, i am so close to having the engine running perfectly with no fault codes. however, I don't have my c101 #14 road speed signal wire (black/white harness side, blue/yellow body side) connected to anything yet.

i have the pin assignment table from my etm, i have looked through all 88 pins, but there is nothing there that is glaringly obvious.

since i am doing obd2, this will make the question tougher to answer. anyway, if anyone knows, please help me out.

as far as i can tell, i just need to fix this and and the o2 sensor heaters and i will be fault code free.:blowup:

[FredK]

X6000 Pin 15 Speed signal right rear

[flyboyx]

X6000 Pin 15 Speed signal right rear

oh man, thank you an f-load. that is an awesome help.

on my chart it is listed as: input, speed signal, right rear connection to abs/asc control module.

i guess it is the connection that threw me off. i can't tell you how much that helps me out. thank you again.

[flyboyx]

found it! that wire is without a doubt, my#2 in the x20 i just went through and cross referenced it in the etm. man, my wiring diagram is so much different than all of the others posted here.

[mongule]

Yep its an abs/traction control input

Thats what I used and it fixed my 5k rev limiter.

[flyboyx]

man, i wonder who was the rocket scientist who figured out that you could substitute a speedometer out signal for an abs wheel signal and have it actually work? i consider myself a pretty smart guy but...damn!

[Aatos]

This was how I solved my vehicle speed signal error code too. Note that the DME doesn't interpret the signal completely right. DME thinks the car is going alot slower than it really is, roughly by speed/diff ratio (I checked live data while driving). I don't know how significantly this affects vanos timing and ignition (or not) as there isn't much information available on how the vehicle speed is used by the Siemens DME.

As a reference for people searching this, the pin 15 wire colour is brown-red in the engine harness.

[matt]

It doesn't use that signal for much at all. Generally it is either checking to make sure the car is actually moving or using speed dependent rev limits in some versions of the software. Obviously it uses it for the max speed limiter and if it doesn't get a signal at all, it will lower the rev limit at all times because it will think that you've cut your speed signal to bypass the max speed limit.

Also, the signal doesn't have anything to do with ABS... the right rear wheel speed signal for the ECU comes from the diff. That's how the speedo and ECU speed inputs have always worked for BMWs.

[Aatos]

Thats good to know, thanks!

However, according to E36 M52 ETM the source for DME pin 15 is indeed the ABS/ASC module, pin 21. There is no connection between the ABS/ASC module and the rear diff hall sensor as far as I can see. I don't see how the rear diff speed data could be fed to DME in the original E36 M52 system?