1995 BMW 740i ABS Connector


The ABS part number is 34511090910 and was used on 7 series BMW from 1994 to 2002. It was also used on 5 and 8 series and Z series but in different years for different models.
BMW switched to a different ABS unit when it added DSC in later models. This older model of ABS just has ABS / ASC

Watch the video here...
https://www.youtube.com/watch?v=ckKaHIYfv4M&feature=youtu.be

The ABS pump motor is pin 3 on the 15-pin connector.

Measure with a multimeter from pin 3 to ground and you should get about 3 to 10 ohms.
(The body of the ABS unit is ground)

That measurement is the resistance through the pump motor.

 

 

This is the ABS opened up.
The wire in the middle with partial gray insulation has degraded over the years and become brittle.
Vibration of the pump motor makes the insulation fall off in pieces and eventually you have a bare wire.
That bare wire touches the body of the ABS and shorts out the pump.
The symptom is that the ABS and Traction Control lights come on and will not go off until you turn the car off.*
It also disables the ABS brakes and traction control while those lights are on.
This will most likley be an intermittent problem and may be temperature sensitive.
Measuring from pin 3 to ground with the ABS unit cover closed will show a low resistance when you have a bare wire
(anywhere from zero ohms to 2 ohms.)
The normal resistance should be about 3 to 10 ohms.

* NOTE: The wheel sensors can cause the same symptoms with the ABS and Traction Control lights coming on.
DO NOT USE THIRD PARTY WHEEL SENSORS. It is tempting to buy them because they are half the price of BMW originals.
But you can have intermittent failures with non-BMW sensors.

The only way to properly test wheel sensors is with INPA software using the wheel sensor test when the car is moving.
It is possible to never see an ABS / Traction control light and still have intermittent wheel sensor problems that only INPA can detect.

Rich Love

richlove@mac.com