View Full Version : E32 735i Power Steering

03-26-2005, 11:34 AM
Hey guys, my parents have a 92 735i and the power steering is not working right. It works for a few minutes, and the power steering cuts in and out. Anyone have a similiar problem or know how to fix it? I would appreciate any info, we are going to go try draining the fluids and w/e else it takes to try to get this thing working. :)


03-26-2005, 08:26 PM
Look at the bottom of the steering box. You can temporarily check out that the rest of the system is functional by removing the Servotronic module, located in the left kick panel and plugging the two connectors into each other. This gives FULL BOOST to the Power Steering, but also runs the risk of burning out the Servotronic Converter.
So just make it for a short test period, although it is said that this is for emergency purpose when the servotronic is out of order.
Check the plug on the bottom of the power steering box - a fairly easy but messy job. Then after you have found and removed the Servotronic box, check for 12v across the two outside pins of the plug which goes into the connector marked TACHO.
Then check the other connector, going to the steering (LENKUNG). I seem to remember 10 or so Ohms across the two outside pins (the coil of the solenoid in the steering box).
I took my servotronic controller apart last year and replaced the output transistor as it was dead. It's the one second back from the connectors in the middle. I can't remember what I replaced it with but ZTX653 comes to mind.
Do not waste your time and (do what I did) remove the big 'transistor' riveted to the circuit board on the left hand side - it's not a power transistor; it's just a standard +5V regulator for the processor!!
The old servotronic control module is replaced by a newer one of completely different size.

32 43 1 162 703 (servotronic unit, updated version)
32 43 1 162 736 (wiring harness adapter for above)

The servotronic unit now looks more like a conventional relay with spade terminals. The wiring harness adapter simply let this unit plug into the two round multipin connectors of the car wiring harness.
Up to production 9/93, must be used in conjunction with 32 43 1 162 736 installation kit.
Also read this info from the German board where I wrote something about it, incl. pics