Transfer Case Actuator Issues?

[TCMoto]

Hi,

I have two codes popping up on my 2004 E53 3.0 (129,000 miles):

ABS-DSC DXC8
Dynamic Stability Control
5DEA/ Not Present
DSC: Transfer Case: Temperature

and

ZKE Central body electronics
80
GM: Servotronic servo valve. open circuit

Not sure if they are related. They are the only codes after a recent 1000 mile road trip (I checked the TC fluid level before the trip). After doing some research I'm thinking there is something going wrong with the transfer case actuator? I don't have any warning lights on and the actuator isn't making any noise. I changed the TC fluid when that code came up awhile ago and reset the calibration.

I've always been proactive with repairs and am tempted to just go ahead and replace the actuator before the plastic gears give out.

Any thoughts?

Thanks,
Alex

[wpoll]

Check the plastic gear - in some cases a worn gear can present the faults/code you are seeing.

It's easy to check (and replace) and is the first place to look.

If that's OK, then the steering angle sensor may be suspect; although the codes don't point to the SAS, once again these codes have been presented in cases where the SAS is worn.

The other code appears to be related to the Servotronic steering. I'm not sure how/if the Servotronic steering interfaces with the DSC. I think it does, so they me be related. Is the steering heavy (more than normal I mean!)?

[Clavurion]

You can also remove and rotate the plastic wheel 180 degrees to get new contact surface.

Servotronic is only connected to DSC by the wheel speed sensor signal (vehicle speed) coming from left rear sensor (same as instrument cluster). In this case the code is for Servotronic solenoid and likely too small resistance caused by tired solenoid. You can measure the solenoid resistance via the body module connector pins. If resistance is below 7,5 ohm body module will show this trouble code.

[TCMoto]

Thanks for the replies.

I'll plan on just replacing the whole actuator. I plan to keep and drive this X5 for a long time and I've already made a lot of repairs on it. The BMW gear repair kit is $100 and a Bosch OEM actuator is $400. The gear replacement repair doesn't seem too horrible but just bolting on a new unit will be much easier without the concern that I didn't do the gear correct. Is it possible for the resistor on the actuator to go bad? Should I replace that as well?

The steering is normal, not heavy. I did read that the second code could be related to the Servotronic steering. I suppose if the second code comes back after the actuator repair then I'll look into that and the SAS.

I recently replaced the rear brake hoses and the speed sensor seemed fine as in still there and connected to the knuckle and in the plastic junction box. Is it possible for those to go bad?

[Clavurion]

Originally Posted by TCMoto

Thanks for the replies.

I'll plan on just replacing the whole actuator. I plan to keep and drive this X5 for a long time and I've already made a lot of repairs on it. The BMW gear repair kit is $100 and a Bosch OEM actuator is $400. The gear replacement repair doesn't seem too horrible but just bolting on a new unit will be much easier without the concern that I didn't do the gear correct. Is it possible for the resistor on the actuator to go bad? Should I replace that as well?

The steering is normal, not heavy. I did read that the second code could be related to the Servotronic steering. I suppose if the second code comes back after the actuator repair then I'll look into that and the SAS.

I recently replaced the rear brake hoses and the speed sensor seemed fine as in still there and connected to the knuckle and in the plastic junction box. Is it possible for those to go bad?

No problem if you want to replace the whole actuator. I was just mentioning this rotating option as it doesn't cost anything and still should work for ages. You don't even have to open the gear side. Just mark the original position of the gear. Remove motor, clean plastic debris out of the gearbox, rotate the wheel 180 degrees, add new grease and insert the motor back.

If the steering assist works correctly you don't have to worry about that solenoid code. If the code is active servotronic will go to failsafe mode and the assist is the same regardless of vehicle speed (heavier than normal rack without servotronic). This code has nothing to do with DSC or wheel speed sensors. If that rear left speed signal was lost the instrument cluster speedo wouldn't work and on GM there would be a different code "speed signal A".

[wpoll]

Originally Posted by TCMoto

Thanks for the replies.

I'll plan on just replacing the whole actuator. I plan to keep and drive this X5 for a long time and I've already made a lot of repairs on it. The BMW gear repair kit is $100 and a Bosch OEM actuator is $400. The gear replacement repair doesn't seem too horrible but just bolting on a new unit will be much easier without the concern that I didn't do the gear correct. Is it possible for the resistor on the actuator to go bad? Should I replace that as well? ...

The classification resistor is to allow for "calibration" of the X-Drive system (and is selected/setup in the factory assembly line). Which leads to the assumption that if you change the entire transfer case, you need some way to select the correct classification resistor.

BUT, it seems that many folk have replaced the transfer case, paying zero attention to the classification resistor, resulting in a working X-Drive system. The reverse is also known to be the case (a bad classification resistor replaced with a random replacement, with good results).

Replacing the actuator unit only should not require replacement of the classification resistor.

The BMW TIS states: -

VTG actuator motor with incremental sensor and classification resistor

The VTG actuator motor (VTG: transfer case) opens and closes the multi-plate clutch. The location of the actuator motor shaft and the adjustment rate are detected by the incremental sensor.

The classification resistor ensures that mechanical tolerances in the transfer case are considered. Optimum function is thus ensured.

Classifying resistance:
The locking torque characteristic curve of the multi-plate clutch may vary slightly due to mechanical tolerances during the manufacture of mechanical components.

The actual characteristic curve for a transfer case is recorded by means of clutch test stand after assembly. This characteristic curve is compared with the characteristic curves stored. The best possible characteristic curve is selected.

Each characteristic curve stored has a classification resistor as an identifier. After completion of assignment the classification resistor is installed on the transfer case.

In the vehicle, the resistance value is imported from the VTG control unit. The software automatically sets the established characteristic curve. This setting is made whenever the engine is started or is checked whenever the engine starts.

[TCMoto]

The "open circuit" part of the second code and my concern that the two codes are related keeps making think it's an electrical problem with the actuator motor or resistor. I'm a civil engineer and barely passed circuits 101 so I'm always afraid of an electrical problem that I can't deal with myself. I did read about the resistor being matched to the TC at the factory and would prefer not to replace if it's not bad.

I do plan to support the TC and take off the cross member to get to the actuator. Do you know if that is a big hassle in case I need to get back to the actuator if the gear flip or gear replacement doesn't clear the code(s)?

Thanks again for the replies. If it's poor taste to reply all and not quote replies let me know. I'm new here.