Power Steering Issue

[o2bad455]

Progress: The result was 7.7 ohms between pins 1 and 2 (looked like a blue and a green wire, respectively) at the SVT module connector behind the glovebox. Assuming that's the actual resistance at the servotronic valve itself, does anyone know if it's within spec? I do have some manuals (possibly just for E30 and/or E53 rather than E83 - can't remember) but they're elsewhere. I'd read on another forum that 4 ohms was good but 7 ohms was bad, but that might be for a different part number.

Where might I find the correct servotronic valve part number for this 1/2008 E83? FCP (my usual go-to) lists one for just about every other BMW except E83 X3.

Procedure: I scanned for fault codes, then disconnected the battery (is there a way to reopen the hatch without power?), got the glove box apart (much different than write-ups so they must have changed it for LCI - mine used phillips rather than torx), and tested the impedance (technically just resistance) between pins 1 and 2 (looks like a blue and a green wire) at the SVT module connector.

This time fault codes were as follows (still no SVT fault and showed green on the tree page, although there is a DSC fault showing and that showed yellow on the tree page):

000004 LWS: Slider fault (adjustment operation) -1
000004 RDC: Wheel detection not possible -1
00002E RDC: Wheel electronics, front left: no reception -1
000031 RDC: Wheel electronics, front right: no reception -1
000034 RDC: Wheel electronics, rear left: no reception -1
000037 RDC: Wheel electronics, rear right: no reception -1
0000BE KOMBI: Data-filing difference to central light module -1
0000A3 MRS: No message from DSC control unit or message incorrect -1
0000A1 MRS: No message from DSC control unit or message incorrect -1
00003C LM: Number-plate light faulty -1
006E3D DSC: Steering-angle sensor, internal (mileage in km)
00578E EGS: Gearbox oil: wear (mileage in km)

[o2bad455]

Oh, since the servotronic valve is supposed to be normally open for bypass (minimum assist), could I try applying a fixed voltage to close it (maximum assist) to see if there's any difference (basically just to rule out the pump itself)?

[RocketyMan]

Originally Posted by o2bad455

Sorry for my slow follow-up. With the holidays I haven't had time to even pull the glovebox apart for the multi-meter test just yet. I did read over on the M5board that a bad servotronic valve almost always throws a code. Otherwise, the valve seems easy enough to replace with just removal of the drivers front wheel and a couple of torx bolts to free it from the rack (assuming they don't strip). They also said 4 ohms is good but even a few ohms different is bad, FWIW. So hoping to finally test the valve resistance soon.

Since I've still got no relevant code, though, it does seem at the moment to more likely be an actual pump or rack issue in my case. Not wanting to deal with the rack itself, I can get a 2007 pump (since our X3 is 1/2008 production, but I think the pumps changed in 3/2008) and will probably see if that helps after confirming the correct valve resistance. Hopefully no pump difference for servotronic - I'm assuming just the rack with servotroinic valve would be specified differently with versus without the option. Next I just need to figure out how to get at the pump - hopefully from the top.

If the valve resistance seems okay and the pump replacement doesn't help, then I'll of course swap out the valve, code or no code, before contemplating replacement of the whole rack. R&R of that rack does not look like any fun! More soon...

Thanks for the update. Checking the wiring to the servo still is a must, just to rule it out.
I'm sure you checked the powersteering reservoir and made sure it had oil. I'm not sure how else you can check the pump without connecting up pressure gauges on the lines, but if the servo is diverting all fluid back to reservoir, you will wouldn't be able to check pressures properly. When running the vehicle, does the powersteering get warm at all? Maybe the pump did burn up. I'm not seeing any differences on RealOEM for steering pumps with or without servotronic. But there deff seems to be a difference in 5/2008 when the pumps switched over like you mentioned. Good catch.

Looking at the two diff part numbers, the pump castings look the exact same. The only thing i've noticed is perhaps the pump supplier changed from LuK to ixetic. Same company that bought one another and/or joint venture circa 2007? Under Magna Dyne? Hmm..interesting.
P/N
32413428010

32413450590

[RocketyMan]

Originally Posted by o2bad455

Progress: The result was 7.7 ohms between pins 1 and 2 (looked like a blue and a green wire, respectively) at the SVT module connector behind the glovebox. Assuming that's the actual resistance at the servotronic valve itself, does anyone know if it's within spec? I do have some manuals (possibly just for E30 and/or E53 rather than E83 - can't remember) but they're elsewhere. I'd read on another forum that 4 ohms was good but 7 ohms was bad, but that might be for a different part number.

Where might I find the correct servotronic valve part number for this 1/2008 E83? FCP (my usual go-to) lists one for just about every other BMW except E83 X3.

Procedure: I scanned for fault codes, then disconnected the battery (is there a way to reopen the hatch without power?), got the glove box apart (much different than write-ups so they must have changed it for LCI - mine used phillips rather than torx), and tested the impedance (technically just resistance) between pins 1 and 2 (looks like a blue and a green wire) at the SVT module connector.

This time fault codes were as follows (still no SVT fault and showed green on the tree page, although there is a DSC fault showing and that showed yellow on the tree page):

000004 LWS: Slider fault (adjustment operation) -1
000004 RDC: Wheel detection not possible -1
00002E RDC: Wheel electronics, front left: no reception -1
000031 RDC: Wheel electronics, front right: no reception -1
000034 RDC: Wheel electronics, rear left: no reception -1
000037 RDC: Wheel electronics, rear right: no reception -1
0000BE KOMBI: Data-filing difference to central light module -1
0000A3 MRS: No message from DSC control unit or message incorrect -1
0000A1 MRS: No message from DSC control unit or message incorrect -1
00003C LM: Number-plate light faulty -1
006E3D DSC: Steering-angle sensor, internal (mileage in km)
00578E EGS: Gearbox oil: wear (mileage in km)

Yeah when disconnecting the battery, I usually leave a rag in the tailgate catch to prevent the catch from locking. At any rate, you can apply power to the jump posts under the hood. HOpefully you have the hood still open, ya?

I still don't like that you cannot see ANY of the wheel speeds. This seems to point to the ABS (DSC) module is NOT reporting on CAN...?

You just reminded me. Let me take a look on my service manual for the e83 to see if there is a value for the servotronic.

[RocketyMan]

Originally Posted by o2bad455

Oh, since the servotronic valve is supposed to be normally open for bypass (minimum assist), could I try applying a fixed voltage to close it (maximum assist) to see if there's any difference (basically just to rule out the pump itself)?

It's suppose to be a PWM signal to the solenoid. Applying 12 volts to it would basically set it to 100% duty cycle.

Originally Posted by o2bad455

000004 LWS: Slider fault (adjustment operation) -1
000004 RDC: Wheel detection not possible -1
00002E RDC: Wheel electronics, front left: no reception -1
000031 RDC: Wheel electronics, front right: no reception -1
000034 RDC: Wheel electronics, rear left: no reception -1
000037 RDC: Wheel electronics, rear right: no reception -1
0000BE KOMBI: Data-filing difference to central light module -1
0000A3 MRS: No message from DSC control unit or message incorrect -1
0000A1 MRS: No message from DSC control unit or message incorrect -1
00003C LM: Number-plate light faulty -1
006E3D DSC: Steering-angle sensor, internal (mileage in km)
00578E EGS: Gearbox oil: wear (mileage in km)

I think these are your problems. The SVT will go into limp mode if it does not see a rational road-speed signal within the first 5 seconds of vehicle start. This seems to be your culprit and coincides with no assist because of no road-speed signals at any wheel.

[o2bad455]

Originally Posted by RocketyMan

Yeah when disconnecting the battery, I usually leave a rag in the tailgate catch to prevent the catch from locking. At any rate, you can apply power to the jump posts under the hood. HOpefully you have the hood still open, ya?

LoL - I actually tossed a pair of gloves at the hatch latch but heard a telling click while I was dealing with the glovebox and sure enough it had partially latched despite the gloves. I guess they were too thin! Ended up using a jumper pack under the hood just to get the hatch opened, but it made me think there must be a safety relaease somewhere in the trunk area that I should learn about. I could reach the trunk from the back seat, but couldn't get the tilting floor piece out of the way to reconnect the battery without re-opening the hatch.

Originally Posted by RocketyMan

I still don't like that you cannot see ANY of the wheel speeds. This seems to point to the ABS (DSC) module is NOT reporting on CAN...?

Wheel speeds or tire pressures? I thought those codes were just for tire pressures... I think I mentioned it earlier but the lack of pressures is only since swapping to the winter tires. I assume they either don't have sensors or perhaps all the batteries are dead. I did have working tire pressures with our original 19" summer tires, which were still on it when this power steering issue first ocurred including for a subsequent highway drive through a blizzard where AWD worked quite well. I'll see if I can find an old pre-PS-failure scan to see if those were ever present before.

Originally Posted by RocketyMan

You just reminded me. Let me take a look on my service manual for the e83 to see if there is a value for the servotronic.

Cool, thanks!

[o2bad455]

Not clear which of "maximum steering force support" or "minimum steering force support" is mnimum assist or maximum assist, respectively, but it sounds like there should be a change in assist 5 seconds after starting if all were well. I don't think I've tried it that quickly, so I'll head back out and try that now...


As for the PS fluid temperature, I'll grab my IR pyrometer and check that too.

[RocketyMan]

Originally Posted by o2bad455

Wheel speeds or tire pressures? I thought those codes were just for tire pressures... I think I mentioned it earlier but the lack of pressures is only since swapping to the winter tires. I assume they either don't have sensors or perhaps all the batteries are dead. I did have working tire pressures with our original 19" summer tires, which were still on it when this power steering issue first ocurred including for a subsequent highway drive through a blizzard where AWD worked quite well. I'll see if I can find an old pre-PS-failure scan to see if those were ever present before.

Ahh! You're right. The RDC is the TPMS module. Hmmm....

Well I cannot find ANYWHERE stating what the passing values of the solenoid is in the service manual. -_-

[o2bad455]

Oh good about the RDC. Thanks for checking about the ohms.


The part number I was curious about earlier was actually for the servotronic solenoid or valve rather than the pump. For some reason I haven't found any part number indicating an application to E83 yet.

Originally Posted by RocketyMan

It's suppose to be a PWM signal to the solenoid. Applying 12 volts to it would basically set it to 100% duty cycle.

In another forum, I'd read something about a "9V battery" test applying power directly to the servotronic solenoid on the steering rack, but peple were hacking their harnesses to do it. Tempted to try 0V vs 9V through the connector while the glovebox is still apart just to see if there's any difference in actual assist, but want to be reasonably sure it won't fry anything before proceeding...

[RocketyMan]

A little 9V battery should be fine. Try it and see if you get any "clicking" when applying it to it. I don't think you need to hack up your harness tho, just a little creativity.