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GMWrencher
GMWrencher, ASE Certified Technician
Category: GM
Satisfied Customers: 439
Experience:  100% GM Certified ASE Master Automobile Medium/Heavy Truck. Licensed State Auto Inspector
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GM Acadia: 2008 GMC Acadia - What do the Diagnostic trouble

Customer Question

2008 GMC Acadia - What do the Diagnostic trouble codes P0989 & P0752 mean?
Submitted: 1 year ago.
Category: GM
Expert:  GMWrencher replied 1 year ago.
I can help with your request.
Expert:  GMWrencher replied 1 year ago.
Are you experiencing a transaxle shift concern as well?
Customer: replied 1 year ago.
Also what needs to be done to fix these codes? After the transmission wave plate 3rd & 5th gear were replaced we took the car back to the dealership because it didnt feel right and they said they couldnt find anything wrong with it.
Expert:  GMWrencher replied 1 year ago.
I see you requested a phone call. I can help here at this time. Can we proceed?
Customer: replied 1 year ago.
i dont know, all i know is the two dtc codes they gave me and that they said they needed to replace a transmission control module.
Customer: replied 1 year ago.
yes
Customer: replied 1 year ago.
it says you are unable to call right now, how do we proceed??
Expert:  GMWrencher replied 1 year ago.
The most likely cause to your problem is a failed fluid pressure switch. The Pressure switch is not a separable part and is integral to the Transmission Control Module Assembly. The module with switch would need to be replaced and then program and calibrate to the vehicle.
Customer: replied 1 year ago.
the transmission was fixed less than 12,000 miles ago, i find it hard to believe this isnt related in anyway.
Expert:  GMWrencher replied 1 year ago.
While the module is within the transaxle the issue and codes it has now are not related to the 3/5/R wave plate failure.
Customer: replied 1 year ago.
So when the 3/5/R wave plate failure occurred there is no way that the broken pieces could of damaged the module?
Expert:  GMWrencher replied 1 year ago.
The switch failure can occur on units before and after a wave plate failure or not at all. Its basically a rupture in a pressure switch diaphragm that is the cause.
Expert:  GMWrencher replied 1 year ago.
The broken pieces are generally medium sized and trapped well down inside and near the sump and generally never make it through the sump filter.
Customer: replied 1 year ago.
The car was taken back to the dealership the day after the 3/5/R wave plate failure was fixed, for the same issue it is in the shop for now. But since it does it sporadically the service adviser said he could find a problem with it.
Expert:  GMWrencher replied 1 year ago.
The passages within the module are small and are protected by its own screen. So to damage the switch diaphragm it the pieces would have to make it through a filter and a screen. I cant say it would NEVER happen but its generally no the cause..
Expert:  GMWrencher replied 1 year ago.
If its setting the codes you have listed.. the fluid switch has failed. Note: Some customers may comment that the MIL is illuminated. Upon further investigation, technicians may find DTC P0752, P0872, P0877 and/or P0989 as an active or history code in the TCM. This condition may be caused by a faulty fluid pressure switch. This switch is part of the Valve, Control Solenoid Assembly (TEHCM) (#15 in illustration above). Damaged switches typically do not occur until the vehicle has accrued 80,000 km (50,000 mi) or more.
Expert:  GMWrencher replied 1 year ago.
Simply.. the diaphragms just wear out..
Customer: replied 1 year ago.
It is just that the car has had this problem since the day we got it back from having the 3/5/R wave plate failure fixed.
Expert:  GMWrencher replied 1 year ago.
Advice: It is ROUTINE to check these switches visually while the transaxle is apart for the 3/5/R plate repair. I cant report if it was checked in your instance.
Expert:  GMWrencher replied 1 year ago.
Have I answered your questions to your satisfaction?
Customer: replied 1 year ago.
isnt there a way to check them electronically? a visual inspection doesnt seem like it would do much good
Customer: replied 1 year ago.
is it common to have to replace the control modules when the 3/5/R wave plate failure is fixed?
Expert:  GMWrencher replied 1 year ago.
I agree, it does not seem like a "proper" way, but when they fail its visually obvious once apart, Its the opposite when trying to diagnose. As they can be intermittent.
Customer: replied 1 year ago.
Do they usually replace the control modules when the 3/5/R wave plate failure is fixed?
Expert:  GMWrencher replied 1 year ago.
It is NOT common to replace the module with the 3/5/R repair, but it IS common to check the switch diaphragms and IF an issue is found.. yes then replace the module.
Customer: replied 1 year ago.
If this has been an issue since it was fixed, it doesnt seem to me like they checked the switch diaphragms.
Customer: replied 1 year ago.
Since they are not part of the 3/5/R wave plate failure recall.
Expert:  GMWrencher replied 1 year ago.
Its very possible they were checked then and now failed as well. THAT in particular has happened to me personally. Its also possible nothing was checked at all. Only the technician who performed the repair know for sure.
Customer: replied 1 year ago.
Would you pay the $1300 to get it fixed 12,000 miles after the transmission was torn apart when the car only has 84,000 miles on it total???
Expert:  GMWrencher replied 1 year ago.
Sorry for the delay in response. I do understand your irritation with an additional repair cost. Its really up to the repair facility whether to honor what they repaired or at least come to an agreement. I also understand the additional problems after the fact. The module is not part of the special policy, so even IF the switches were have been found failed would not have been covered. The next step would have been to contact the customer (you) and alert of the potential future issues. I hope I have answered your questions. A positive rating is the only way I can receive credit for assisting you today.
Expert:  GMWrencher replied 1 year ago.
Is there anything else I can help you with regarding your initial question? If not please choose to positive rate my answer to ensure I receive credit for assisting you today with your GMC question.We thank you for using Just Answer.