1999 e38 ABS DSC dashboard lights Sensor problem

[MrChrysler]

Hi,

In the past months the abs and traction control lights came up together maybe 3 times for a minute or two, over long period of time.
The last time it came up on 9 months ago and it stayed like this till now.

I've got an Error code 31 - Which is Rear Right Wheel speed sensor.

I replaced the sensor, cleared the codes, and it came back on immediately after turning a key.

Later I have measured the resistance of a circuit from the ECU to the plug where the sensor is located.
On the left side - the resistance is about 26M ohms which is correct, on the right side it indicates an Open circuit - no connection with ECU.

What are your suggestions? I did not see any damage to the plug or wire where the wheel is.

Could it be this?
http://www.meeknet.co.uk/e38/ABS/Index.htm

or damage on the ECU board?

I got some pictures

[oldroller]

Test the right rear circuit validity at the ABS module plug, disconnected. Measure at pins 30 & 31 (RR) for resistance, and perform a diode check with your DVOM on the same pins.
You should find the diode triggers with the leads connected one way, and 'OL' or open circuit when you switch the test leads.

Hopefully you replaced the sensor with a Seimans unit, not aftermarket.

If readings are not correct, disconnect the sensor from the harness at the wheel and check the continuity of the wires from the rear to the ABS connector. This will verify wiring validity.
Checking the diode function and resistance at the sensor is easy at this point.

Does the cruise control (fed from RR) work normally? If the wiring and sensor test well and the cruise works it is likely the ABS module has a faulty circuit.
BBA Reman in Taunton Mass has a service to rework the Bosch modules, $95 on Ebay. They will test the unit and refund the fee if the unit is good. They cover shipping also.

[carnut1947]

99% of the time its the ABS module.

[MrChrysler]

Hi, thank you for help.

I have measured for resistance between pins 30 and 31, the resistance turned out to be 26M ohms, which all good. Luckily my module is fine.

Next I have checked the wire and the plug itself on the module side, not on the sensor as it easier to do.

I think that pictures will explain what happened best.

For those who read this, pins 13 and 29 are for the rear left. (when you measure resistance on the module - if you didn't get the readings for the first time, change polarity, (black and red cable) and measure again)

WP_20171207_13_14_12_Pro.jpgWP_20171207_13_40_19_Pro.jpg

[MrChrysler]

Is it normal that the sensor needs to be calibrated?

My ABS kicks in at very low speeds

INPA does it?

[georgebest]

INPA does it?

yes, but I have never done it myself so no clue how to do it.

[carnut1947]

I went all though this and replaced the ABS module and had it calibrated at a local indy. shop. There are many on EBAY that will do it on one on an exchange basis. approx $!00.

[MrChrysler]

Guys,

I bought Mahle speed sensor - not Siemens

Now I got error 41 from the DSC/ABS which mean something like pulsating signal.

When I look at the wheel speed in the INPA - All wheels hold steady value apart from mahle - It shows the same speed like others but It has sudden speed spikes/jumps for a second, and then its fine.
Its triggering traction control and ABS all the time

What makes do you recommend apart from Siemens?

The worst thing is that the old sensor itself was fine, it was just a broken wire, unfortunately It came out in about 100 pieces.

[MrChrysler]

I have replaced the MAHLE sensor with BOSCH - Works perfect