Questions on My New 2008 GXP

[bocoogto]

We bought this GXP last week. All is great with the car except for some tire noise, which the previous owner alerted us about. The tires are less than 1/2 worn, so we'll have to put up with this for some time.

My concern is the ABS/Stability System/Traction Control. The warning light came on yesterday. I had the codes checked by Advance Auto Parts and deterimined the problem was the right front speed sensor. I think I've found the problem where the wire harness passes under the front of the engine. The insulation rubbed off some of the wires against a metal wire holder. I moved the harness a little so the bare portion is not shorting to the wire holder and the problem went away. I plan to fix the insulation problem and protect the wires from the holder as a permanent fix.

The code reader showed a total of 7 codes. One was the speed sensor. Another was the oil pressure sensor. Another was a communication problem between the engine and computer. I can't remember the rest of the codes. The engine runs fine and the "engine" light is not on.

Can I reset these by disconnecting the battery?

Also, I've noticed an intermittent problem when stopping that the car shudders as though the transmission did not downshift. The brakes are smooth--no shudder there. Is this a serious symptom with the 460LE transmission?

 

[bocoogto]

Here are a couple of pictures. I kept editing them until the system allowed attaching. Too small, but maybe I'll find a better method.

 

[Fivefingerdeathpunch]

It's likely those codes are just history codes from however long ago. Disconnecting the battery for a half hour should clear the memory. If you want you can disconnect the battery on both ends, let it sit for 30min and then touch the cables together to fully discharge.

Look up triple edge performance, he builds these transmissions for a living and has several common issues listed on the website. See if anything lines up there. Also the transmission is called the 4T65e HD in your vehicle.

 

[Gregorius]

We bought this GXP last week.


Also, I've noticed an intermittent problem when stopping that the car shudders as though the transmission did not downshift. The brakes are smooth--no shudder there. Is this a serious symptom with the 460LE transmission?

First thing I think when I hear this, does it only happen when you are in Manual mode, Tapshifting>? I will downshift to 2nd or 3rd coming up to a stop, and will forget about it. It'll hold 2/3 down till about 5 miles an hour, then drop into 1st on it's own, causing a little shake 'n' bake, because it seems to want to engage 1st before the TC lets go.

 

[bocoogto]

First thing I think when I hear this, does it only happen when you are in Manual mode, Tapshifting>? I will downshift to 2nd or 3rd coming up to a stop, and will forget about it. It'll hold 2/3 down till about 5 miles an hour, then drop into 1st on it's own, causing a little shake 'n' bake, because it seems to want to engage 1st before the TC lets go.

No, it does it in Drive. I've tried stopping in neutral, and naturally, it does not shudder.

Thank you.

 

[bocoogto]

Solved the ABS/TC/Stability alert problem. The wire harness under the front of the engine was rubbing on the wire support which rubbed off some insulation. I taped and clad the harness and the problem has gone away. There is A LOT of heat in that area below the exhaust manifold.

I've tried stopping after shifting to neutral and the shaking problem does not happen. Also, if in the Tapshift mode, stopping when in first gear does not cause the shudder. The problem seems to be failure to downshift early enough when stopping.