Buick Rendezvous P0729 and P0723 Transmission Codes

Transmission Problems on my 2005 Buick Rendezvous AWD light on. GM Computer codes P0729,P0723. Checked all connections to sensors in wheels and transmission. Fluid has been changed as recently as 5k prior to problem. No repairs just troubleshooting, had codes cleared, problem re-appeared.

2005 AWD Buick Rendezvous 3.6Lt, Speedometer erratic, lurching acceleration and shifting at moderate speeds around 35 to 50 MPH, AWD illuminates and goes off unable to set cruise control odometer reads error. Had codes cleared problem re-appeared, checked wiring to PCM ohm checked wiring harnesses from wheel bearings and from sensor in transmission all OK.

Can the sensor in the trans be accessed by the pan? Is this a common problem with the Buick transmission? Should I first replace the harness to the PCM? Last question if it has to be fixed in the transmission can a DIY selfer pull the trans, I'm a very good mechanic.

buick Rendezvous


ANSWER:

My charts are not showing a P0729 for a 2005 AWD. No, this not a common problem. Have not really had this too often. Was wondering why you say checked harness from sensor to PCM. My chart shows vehicle speed sensor wiring goes straight to Trans control Module (TCM). Sensor is on tail / extension housing of trans. Yellow and Purple wires.

Reply:
Sorry 0729 is one of the codes that reads output speed sensor low voltage, and your right again it's the TCM module located adjacent the air filter box. What about the sensors in the transmission itself, can they be accessed by the pan?

The vehicle speed sensor and output speed sensor are on and the same. See pic attached. Look very closely at the wires at the sensor connector. Pull on each wire to see is the colored insulation stretches. If it does, then the copper is broken inside the insulation.

Also, you can remove the sensor, use a mirror to get a small screwdriver on the reluctor wheel in the trans. See if the reluctor moves / spins. If it does, then the wheel is broken. Other that, i would say just a sensor problem. This would obviously affect speedometer, cruise, dash cluster.

Reply:
Ok fabulous, thank you! So the sensor depicted in the picture is removable as shown. If the relucter wheel isn't broken and the wiring is good the sensor can be replaced without removing the transmission. Your advice is terrific.

Yep, you got it. This is your most likely cause.


Buick Rendezvous 2003 Just purchased it -- used. Question = the traction light keeps coming on and the brakes feel like their come up through the floor. It's getting worse. Is this unsafe and who can I go to get it fixed? I need an answer asap as I'm going out of town tomorrow. thanks.

Answer:
You've most likely got a bad wheel speed sensor, that is part of the anti lock brake system. When these go bad, the symptoms are usually the traction light or ABS light coming on, and an odd feeling in the brake pedal as you come to a stop.

You would need to get the vehicle scanned to see which wheel speed sensor is acting up, as it would have set a code. The sensors are part of the hub bearing assemblies for each wheel. Which ever one is acting up, you'll need that particular hub replaced. That should solve your problem.


Service engine light code said emissions problem. Replaced recommended part. A few days later light back on although care drove ok. Now service traction system light is on and brake pedal acts funny. Are these two problems related? What can i do to fix this?

OK, so what are the codes and what part was replaced? The traction and ABS brakes function together.


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