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Discussion Starter #1
Recently my 07 Acadia developed a bunch of issues that are probably related but I've been unable to figure out the problem and I'm trying to avoid a dealer for a 11 year old Acadia. It started with the Stabilitrak light coming on any time I was going downhill or slowing down (similar to the automatic engine braking found on some cars to keep from speeding up going downhill) and go out if I was accelerating or going uphill. Soon afterwards (a few weeks), the Traction Control message popped up saying it needed serviced, the AWD has been deactivated (another message), and possibly the ABS light. One strange symptom occured on the RRear wheel when making a sharp turn, such as backing out of a parking space and turning the steering wheel full range when moving out (to the right...I'm not sure if you pull out to the left)...the right rear wheel will drag, seeming like the brake wasn't releasing fully. You can hear a braking noise there as it releases after recovering rom a hard turn. This only seems to happen at very slow speeds, such as pulling in/out of a parking spot or turning onto a road from a stop..
Checking it out on a scanner, a diagnostic message indicated a problem with the comms to the RRear wheel sensor, which was replaced to no remedy. Any suggestions as to whet could be causing these problems? Any and all help is appreciated.
 

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Did you check the hub for bearing wear? What's the condition of the magnetic ring inside the hub which sends signals to the wheel sensor?
 

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Many of the described symptoms (even IP messages) suggest a mechanical wear problem. That would require a visual examination, not something which could be detected with a scanner.
 

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Discussion Starter #4
The sensor was replaced in the right rear wheel after codes indicated a lack of a signal from the sensor. After replacing it, the problem remained and still was showing a comm issue. I'm not sure how easy its going to be to try to test the signal lines to see if it is a wiring/hardware issue or possibly a defective component that processes the sensor's data. The dragging wheel has me a little stumped, as the ABS, Traction Control, and Stabilitrak are all indicated as being non functional via the dashboard warning lights. If everything is disabled, then the braking system which is part of the stabilitrak/Traction Control system shouldn't be engaging. Of course, I don't know the full logic flow that explains the systems, so I could easily have assumed things that shouldn't be assumed.

Jim
 

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... If everything is disabled, then the braking system which is part of the stabilitrak/Traction Control system shouldn't be engaging.
The brakes are hydraulic. They will work even though electronic manipulation systems (ABS, TractionControl, StabliTrak) have failed.
 

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... The dragging wheel has me a little stumped, ...
This sounds suspiciously like a hub bearing problem. Any wiggle in the hub could cause the magnetic signal-generating ring (also, tone ring or reluctor) to break, or disintegrate and cause a loss of the electronic signal to the wheel speed sensor.

 

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Discussion Starter #7
The dragging wheel seems to be a traction control issue or similar problem...it only happens at very slow speeds when making a hard turn...a right turn causes it to drag, I'm unsure about a left turn but don't recall having problems. The problem is mostly notable when first starting the car up and driving...I don't recall it happening after driving it for a little. The problems started all at once with no warning. The right rear wheel quits dragging within a few yards of driving and is accompanied by a "groaning or grinding" type of noise coming from the R Rear area...sort of like something being released slowly as opposed to a clunk or rotor/brake pad noise.
Once on the road, it runs well other than the constant parade of error messages and christmas type lights on my dash. The code given (I can't recall the exact code ID#) indicated a problem with communications with RRear wheel sensor. The sensor was replaced but the problem remains. Its probably a bad or corroded wire..I'm hoping. I couldn't imagine what a dealership would charge for this batch of problems...the 07 isn't worth too much to begin with and has more nagging problems than the remainder of my 6 cars combined. The dragging wheel is the only thing that is confusing me, since the traction control and stabilitrak are disabled and shouldn't affect the braking system. It doesn't sound anything like an ABS activation, although this error message also scrolls across the viewspace along with the Traction, Stabilitrak, and All Wheel Drive error messages.
*Sigh*
 

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Can't help you any further until condition of the tone ring on the wheel hub and the hub itself are checked. That tone ring is where a signal starts for every DIC message you have discussed.
 

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Discussion Starter #9
I spoke to a mechanic today and he suggested an easy way to possibly determine where the problem might be, although I don't know if his advice translates to an Acadia. He indicated that, since the sensor was replaced and the problem remains, one of his methods for checking is to switch the connections from the rear sensors (right and left) and spinning the wheel. If the rotation is "read" on one side but not the other, and the issue follows the swapped connections, then the problem is more easily diagnosed by eliminating some potential issues.
I'm not versed enough with the intricasies of the wheel sensors, but if no signal is found coming from the sensor itself, which was already replaced, then the problem probably lies in the hub. Ringing out wires has never been my favorite and I have no idea how or where the sensors connect to the control unit. Thank you for all of the help. I'm trying to assist my regular mechanic on possible solutions and troubleshooting techniques that might be helpful...I can't afford to take this to the dealer. One look at all of those dashboard Xmas lights and they would plan a Bermuda vacation!
 

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Discussion Starter #10 (Edited)
Just an update on the tire dragging issue. I've discovered that the "tire dragging" happens anytime I'm making a sharp left or right turn, with either the LR or RR wheel dragging a little when I make a turn in the opposite direction...sharp right turn, RR wheel drags. Sharp left turn, LR wheel drags. This only seems to happen at very low speeds, such as when I'm leaving a parking lot space, and I put the car in drive after backing out and turning hard left or right to get out of the space. It doesn't drag when going backwards to the best of my knowing and each side makes a groaning noise for a few seconds before whatever it is making the noise releases and the wheel once again turns normally. The newest thing I've learned is that the wheel also drags when making a very sharp turn, even with the transmission in neutral. The noise and feeling feel strictly mechanical in nature...there is no pulsation or anything that feels part of the normal braking system and no pedal feedback. If you were to ask me what the problems sounds like, I would almost say it sounds a little like a parking break that is sticking, but the parking brake is never used except rarely.
I was beginning to think it might be a problem with the rear end, but the noise comes from something in the wheels and sort of sounds like a large semi truck's wheels when they oscillate upon stopping...you can feel it in the car body and as I said, it is kind of a grinding/groaning noise which sounds like something partially stopping the wheel from turning freely, almost like a stuck noisy emergency brake. If it had anything to do with the normal car systems, I wouldn't expect it to continue to cause problems in neutral, so I don't believe it is anything driveline related and the antilock doesn't activate when it makes the noise, although I'm not sure the antilock is working at this point. Is there anything in the rear wheels that could cause this problem? It sort of feels like a old school 4X4 when you made a sharp turn with the wheels locked in...the front tires would sort of bind and hop when making a sharp turn. This is a similar feeling, except in the rear wheels, not the front.
 

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You've been working on this thing for nearly 4 weeks and haven't found a solution, yet? :shrug: :sosad:
 
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