Hard/heavy steering - possibly GM?

[01740ISP]

I have been having hard/heavy steering since I bought this car 4 years ago. (most notably at low parking lot speed)

• I changed power steering fluid and it did not help much.

• I changed power steering pump and it did not help (old power steering pump was good but I stripped one of the holes for the banjo bolt )

• I cleared the codes with INPA several times and it does not help. I have been getting code 129 (not 130 like others). No other codes with the car

• I cleared the codes with DIS and it did not help.

• I tried the battery nap for 24 hours and it did not help.

• I ran the 9 Volts test suggested by Edwin (read on another forum). With the 9 volt battery hookup, the steering becomes unbelievably smooth. It is night and day.

This leads me to believe that there is nothing mechanically wrong with the car.
The only thing left in my mind is the general module so I removed it from the car and upon inspection, the board does not seem to have any water damage but I can hear a small rattle inside. I read somewhere that it could be normal.

Before I spend money on a general module, is there anything else I should be looking at? It seems unlikely that the wire from the electro-hydraulic converter to the GM could be bad
Can the general module be tested somehow? via multimeter for example?
How would one go about doing it if possible?

-Messan

[shanecarmaster1]

Check the servotronic motor, or see if it's even plugged in first!

I have to say: I thought I wanted the heavy steering, but the feel of the steering unmodified is amazing with perfect weight. The heavy steering lost the agile, tossable, and nimble feeling for me. When I plugged the servotronic back in after about 6 months, I instantly fell in love again.

MORAL of the story: Fix it and you'll be extremely happy.

[fingersmazda]

I also vote servotronic. And agree with shanecarmaster - I drove with and without - infinitely more enjoyable with it.

[stritarja]

There is no "servotronic motor." What most here call the servotronic is what 01740ISP correctly calls the electro-hydraulic converter, which is a solenoid controlled by the servotronic, which is part of the general module. The voltage supplied by the servotronic to the electro-hydraulic converter regulates the flow of power steering fluid through the steering box, and thereby the amount of power assist

You can test the functioning of the electro-hydraulic converter with DIS if you have it - you don't have to fiddle with the wiring and do the 9 volt battery test.

01740ISP, what was the description of fault 129 and did you get a screen shot you can post? Were there follow-up diagnostic tests suggested by DIS?

[01740ISP]

Below is the error I received this evening.


E R R O R M E M O R Y R E P O R T
-------------------------------------

Date: 04/18/12 20:31:03
ECU: ZKE3 GM1
JobStatus: OK Y
Variant: ZKE3 GM1
-------------------------------------------------------------

RESULT: 1 errors in error memory !
-------------------------------------------------------------

129 short circuit servo-valve or cable

Error frequency : 31

Static error
================================================== ===========



In the past,
I received the following 129 and 113(shadow memory report):
S H D O W M E M O R Y R E P O R T
---------------------------------------

Date: 12/18/11 20:24:22
ECU: ZKE3 GM1
JobStatus: OK Y
Variant: ZKE3 GM1
-------------------------------------------------------------

RESULT: 1 errors in error memory !
-------------------------------------------------------------

113 short circuit servo-valve or cable (SERV1, SERV2)

Error frequency : 1

Static error
================================================== ===========

and



S H D O W M E M O R Y R E P O R T
---------------------------------------

Date: 12/18/11 20:24:22
ECU: ZKE3 GM1
JobStatus: OK Y
Variant: ZKE3 GM1
-------------------------------------------------------------

RESULT: 1 errors in error memory !
-------------------------------------------------------------

113 short circuit servo-valve or cable (SERV1, SERV2)

Error frequency : 1

Static error
================================================== ===========


I do not have confidence in my DIS setup since it is unable to do diagnosis. It just reads error. It may be the cable I am using (ebay cable). dis is unable to communicate with the general module for diagnosis.
When doing a quick test of all the modules, I get an error 81 which also points to servo valve short circuit.
Screenshot below:



-Messan

[stritarja]

I do not have confidence in my DIS setup since it is unable to do diagnosis. It just reads error. It may be the cable I am using (ebay cable). dis is unable to communicate with the general module for diagnosis.
When doing a quick test of all the modules, I get an error 81 which also points to servo valve short circuit.

Code 129 that you read with INPA is the same as code 81 in DIS (DIS reports hex numbers for the E38, and 81 hex = 129 dec). I don't know what the difference is between codes codes 129 and 113, since the descriptions iare the same.

I'm not sure what you mean by not being able to do communicate with the general module for diagnosis - if you can read the general module (ZKE) with the DIS quick test you are communicating with it. Do you mean you get an error when you click the green arrow in the lower right of your screenshot (circled in red below)?



In your case, I doubt that DIS diagnostics would do much more than confirm that there is a short. The fact that the 9 volt test shows the servo-valve (electro-hydraulic converter) works suggests that the short is in the wiring from the general module to the electro-hydraulic converter. Check for a short at the general module connector to evaluate the electro-hydraulic converter and wiring together. If you see a short, disconnect the electro-hydraulic converter and see if you still have a short. You can find the general module and electro-hydraulic converter pin-outs in the WDS.

If you don't see a short in the electro-hydraulic converter or wires from the general module, the problem is probably in the general module. There's no simple way to test the module with a voltmeter, but there is a guy (Scott Johnson) who repairs the e38 general module (GM3) for $99.

[01740ISP]

Code 129 that you read with INPA is the same as code 81 in DIS (DIS reports hex numbers for the E38, and 81 hex = 129 dec). I don't know what the difference is between codes codes 129 and 113, since the descriptions iare the same.

Thanks, for the explanation.

I'm not sure what you mean by not being able to do communicate with the general module for diagnosis - if you can read the general module (ZKE) with the DIS quick test you are communicating with it. Do you mean you get an error when you click the green arrow in the lower right of your screenshot (circled in red below)?

You are correct. When I click on the green arrow, it tries to communicate with the general module but DIS is unable to get any info from it. It happens on other modules as well.

In your case, I doubt that DIS diagnostics would do much more than confirm that there is a short. The fact that the 9 volt test shows the servo-valve (electro-hydraulic converter) works suggests that the short is in the wiring from the general module to the electro-hydraulic converter. Check for a short at the general module connector to evaluate the electro-hydraulic converter and wiring together. If you see a short, disconnect the electro-hydraulic converter and see if you still have a short. You can find the general module and electro-hydraulic converter pin-outs in the WDS.

If you don't see a short in the electro-hydraulic converter or wires from the general module, the problem is probably in the general module. There's no simple way to test the module with a voltmeter, but there is a guy (Scott Johnson) who repairs the e38 general module (GM3) for $99.

I will check the wiring this weekend as time permits. Thanks for your help.

-Messan

[dazednkenfused]

Any updates?

[2000bmwe38]

i had the same issue, even flushed my fluid a few times thinking maybe it was dirty, then i cleared all the codes the car had with INPA and BAM! my steering is like butter now, not sure what that had to do with anything, but maybe the system locked itself somehow electronically

[AlexDj]

I have that on white 740 I flushed fluid then changed the pump then changed the pump again have few extras still same so now gonna change servo tronic box that Daren gave me just need to heat shrink the wires and will see the results.

[01740ISP]

Any updates?

Checked the wiring and it is fine. This leaves the GM but I have not replaced it yet b/c that means a trip to the indy to drop off the car. I normally do all my repairs but don't feel confident in coding with the setup I have. Would feel more confident if I had the reliability proven IceBox.

-Messan

[AquilaBMW]

I have this issue with my M-Sport right now. I tried clearing the codes once before but that did not help.

[shled]

Clear your codes?

[AquilaBMW]

Clear your codes?

Yup... tried that, no luck.

[shled]

Yup... tried that, no luck.

That's interesting as the GM stores thirty low voltage codes before turning off servotronic and images above show thirty-one. Just sayin'.

[AquilaBMW]

That's interesting as the GM stores thirty low voltage codes before turning off servotronic and images above show thirty-one. Just sayin'.

I am newbie with the Icebox, might have done it wrong. I will try it again. I need to reprogram some stuff anyway.

What's the best application to use for this?

[dazednkenfused]

Michael, I think I need have mine scanned...can't single hand flick the wheel mid-drift anymore.

[S.Hafsmo]

I've got the same problem. I ordered the solenoid, but that's probably not the problem..
Is it correct that this solenoid is located inside the fender on the drivers side? And that would be the place to test it with a 9v battery?

[DriftinDaddy]

I've got the same problem. I ordered the solenoid, but that's probably not the problem..
Is it correct that this solenoid is located inside the fender on the drivers side? And that would be the place to test it with a 9v battery?

Yeah, if you read Edwin's thread here: http://forums.bimmerforums.com/forum....php?t=1388921 he gives location and pictures of the solenoid/servotronic/electro-hydraulic convertor/etc., it goes by many names

That white plug would be where'd you'd feed the 9V to, to rule out GM or wiring.

My car's had sporadic stiff steering since I bought it a few months ago, one of these days I'll get around to fixing it, lol.......

It's my understanding that if your steering is always heavy, your servotronic is probably dead. I'll end up buying mine from http://www.oembimmerparts.com/produc...1141482e38.htm if I can rule out the GM first.

I'm leaning towards my problem being GM because my steering works sometimes, most consistently when the car's sat overnight or at work say, and then the assist starts weakening the longer I drive it.

I plugged in the shop's scanner and cleared the body control module code last night again (there was a code, but it came back "description unavailable?) and my steering worked perfectly last night and again this morning, so I dunno wtf's going on. Since for now, this car is my DD, I can't pull the GM to send off for repair, so if it starts acting up again, I'm just gonna deal with it until I get frustrated and throw a new servotronic on it, or buy a GM and have it coded to swap for mine

[shanecarmaster1]

Yeah, if you read Edwin's thread here: http://forums.bimmerforums.com/forum....php?t=1388921 he gives location and pictures of the solenoid/servotronic/electro-hydraulic convertor/etc., it goes by many names

That white plug would be where'd you'd feed the 9V to, to rule out GM or wiring.

My car's had sporadic stiff steering since I bought it a few months ago, one of these days I'll get around to fixing it, lol.......

It's my understanding that if your steering is always heavy, your servotronic is probably dead. I'll end up buying mine from http://www.oembimmerparts.com/produc...1141482e38.htm if I can rule out the GM first.

I'm leaning towards my problem being GM because my steering works sometimes, most consistently when the car's sat overnight or at work say, and then the assist starts weakening the longer I drive it.

I plugged in the shop's scanner and cleared the body control module code last night again (there was a code, but it came back "description unavailable?) and my steering worked perfectly last night and again this morning, so I dunno wtf's going on. Since for now, this car is my DD, I can't pull the GM to send off for repair, so if it starts acting up again, I'm just gonna deal with it until I get frustrated and throw a new servotronic on it, or buy a GM and have it coded to swap for mine

Sounds exactly like my problems: intermittent, weakens as I drive, etc. Let us know what happens when you figure it out!

[AquilaBMW]

Mine might be a dead servotronic. It's never worked on this car since I owned it.

Can I replace it with the one from one of the spare cars I have?

Ken, we can scan your car one of these weekends when you are free.

[DriftinDaddy]

Mine might be a dead servotronic. It's never worked on this car since I owned it.

Can I replace it with the one from one of the spare cars I have?

I don't see why not, every listing I've seen shows the same pn regardless of yr or length or engine

Ken, we can scan your car one of these weekends when you are free.

I'd be curious what, if any, codes come back, for comparison sake

[bigvettefreak]

I have been chasing down on.off ABS/DSC warning light problems for almost two years. I replaced the svo and the steering was really nice but I have noticed that when the warning lights are on, the steering gets hard again.

I am getting a code for the steering angle sensor. I have a new one and when I have time will install it. then I have to get it programed. I hope this will cure the stupid warning light problem once and for all. I've replaced everything else. I would love to be able to drive the car without tape covering over the warning light areas.

It is much nicer to have a car that you can turn the wheel and not feel like it is a Mac truck.

[01740ISP]

Finally got around to tackling this job this week-end. Had the part seating for years. It was just as painful as I imagined it. stripped screws, Dremel, reciprocating saw and a lot of swearing and it finally came out. The difference is night and day and I like it. Wished I didn't wait 10 years to get this replaced.

The old Servotronic module had the insulation crumbling and the yellow and red wire had no insulation left on some parts. That would definitely explain the short circuit code of 129 I was getting. 113 never came back

-Messan

[georgebest]

Finally got around to tackling this job this week-end. Had the part seating for years. It was just as painful as I imagined it. stripped screws, Dremel, reciprocating saw and a lot of swearing and it finally came out. The difference is night and day and I like it. Wished I didn't wait 10 years to get this replaced.

The old Servotronic module had the insulation crumbling and the yellow and red wire had no insulation left on some parts. That would definitely explain the short circuit code of 129 I was getting. 113 never came back

-Messan

I cant wait to see what you will be fixing in 2029!!