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Dan, Technician
Category: Buick
Satisfied Customers: 24587
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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I have a 2005 Buick Rendevous 3.4L AWD with 162,000 miles.We

Customer Question

I have a 2005 Buick Rendevous 3.4L AWD with 162,000 miles.We are getting a AWD disable signel on the dash. We have, in the past replaced the wheel hubs, and the wheel sensors. The vehicle also has to be warmed up to normal operating temperature, or it will stall, and the rpm's will be eratic, and flucuate above 3500 rpms. We also, while the car was driving, with a code reader connectedto the vehicle, observed that the calculated load is 30%, while ideling, went up to 100% under moderate driving conditions.
Once the car is fully warmed up, it drives fine, although the AWD disable icon remains on
Submitted: 1 year ago.
Category: Buick
Expert:  Dan replied 1 year ago.

Hello, my name is***** high idle and load points toward a bad mass airflow sensor. Unplug sensor to see if it runs better, if so you can try to clean but if that doesn't help replace. The AWD disable light usually means the ​Differential Clutch Pump Actuator Check Valve has failed, here is a picture to help you locate. Let me know if you have more questions or if there is anything else I can do to help. Thanks.

Customer: replied 1 year ago.
Dan, after I start the car, and it is ideling, if I unplug the sensor, it makes no difference, and when I drive the car (before I warm up the car), it constantly stalls- so I will order a new mass air flow sensor.( again, once the car is completly warmed up, the stalling ceases, and the vehicle runs fine)
No one, including the Buick Dealer knows what a Differential Clutch Pump Actuator Check Valve is. What is the correct name, or part number for this part?
Please don't charge my account until I receive some useful information. I will be more than glad to pay your fee, if I can get the info that I need to fix the problems.
Expert:  Dan replied 1 year ago.

I would recommend checking for vacuum leaks with idle problem if unplugging sensor didn't help. I do not have part number for differential actuator but it is the only electronic component on rear differential. If no vacuum leaks are found clean the idle air control valve incase it is sticking. Let me know how it goes or if you run into more questions, thanks.

Customer: replied 1 year ago.
The Buick dealer, after I gave them the last 8 of the VIN (5s562948) told me that this part is called a Limited slip differential clutch pump oil flow check valve- is this the part that you were describing?
Expert:  Dan replied 1 year ago.

That is correct. Let me know if you have more questions, thanks.

Customer: replied 1 year ago.
Dan, after replacing the Mass Air Flow senson ( no difference in performance), and the PVC valve and hoses (there was a small vacume leak from a ripped hose), still no difference. When we replaced the MAP sensor, connected to the fuel pressure regulator, it cured the problem of stalling, when driving the car not fully warmed up.
I still have a AWD Disable icon on the dash, but before I take it to the dealer and replace the oil flow check valve for $460 + tax, i got a new code of U1016, which no one seems to know what it means.Can you give me any insite into what this code means?, and wheter or not it's connected to the AWD Disable, or the oil check valve? Thanks, Neal
Expert:  Dan replied 1 year ago.

This code means one of modules are not communicating. You need to start by figuring out what module is setting code then checking connector condition, check power/grounds, and if good replace that module. This code would not be related to the check valve code. Let me know if you have more questions, here is info on code. Thanks.



Lost Communications With ECM/PCM/VCM


DTC U1001-U1254 in Computer/Integrating Systems