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benz-tech · 08-30-2015, 01:33 AM

update: I have successfully wired in OBDII and can read codes and watch data stream from the DME. Small victories...

I still have the P0500 VSS code, with no vehicle speed registered in the data stream. Soooo, after extensive testing, including running wires every to test, I am unable to get any type of signal to pin 83 of DME to make it happy enough to register a vehicle speed. This includes the E30 cluster output to its DME, the back of the OBC(where it should come from), and directly off the sensor in the differential. I've checked each signal with a scope and the two cluster outputs start at 5v and then have a small drop-down square spike. For the most part, they hang out at 5v but the 0v square spikes become more frequent with speed. The sensor in the diff puts out a pure square wave from 12v to 0v with increasing frequency. I even tried to ground pin 83 off and on by hand in an attempt to simulate a 12v-0v square signal. (im sure it wasn't anywhere near a real square wave) NONE of these inputs give me a VSS reading in the data stream.

My fear, and its a REAL BIG fear, is that the '96 ti w/o traction control still gets some form of speed signal from the E36 ABS module, which I don't and cant ever have.

2 questions, does anyone know if you were to unplug the ABS module on your '96Ti, would your engine speed be limited to 5,500 rpm? 2nd: anyone know what the signal on pin 83 should look like? There are several decent threads on Bimmerforums under P0500 but no one ever seems to reach a real conclusion.

08-30-2015, 01:33 AM	#3
benz-tech Member Join Date: Dec 2012 Location: nor-cal Posts: 50 iTrader: (0) Photo Gallery	update: I have successfully wired in OBDII and can read codes and watch data stream from the DME. Small victories... I still have the P0500 VSS code, with no vehicle speed registered in the data stream. Soooo, after extensive testing, including running wires every to test, I am unable to get any type of signal to pin 83 of DME to make it happy enough to register a vehicle speed. This includes the E30 cluster output to its DME, the back of the OBC(where it should come from), and directly off the sensor in the differential. I've checked each signal with a scope and the two cluster outputs start at 5v and then have a small drop-down square spike. For the most part, they hang out at 5v but the 0v square spikes become more frequent with speed. The sensor in the diff puts out a pure square wave from 12v to 0v with increasing frequency. I even tried to ground pin 83 off and on by hand in an attempt to simulate a 12v-0v square signal. (im sure it wasn't anywhere near a real square wave) NONE of these inputs give me a VSS reading in the data stream. My fear, and its a REAL BIG fear, is that the '96 ti w/o traction control still gets some form of speed signal from the E36 ABS module, which I don't and cant ever have. 2 questions, does anyone know if you were to unplug the ABS module on your '96Ti, would your engine speed be limited to 5,500 rpm? 2nd: anyone know what the signal on pin 83 should look like? There are several decent threads on Bimmerforums under P0500 but no one ever seems to reach a real conclusion. Last edited by benz-tech; 08-30-2015 at 01:37 AM.