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Discussion Starter #1
Here is the problem:

I start the car, and either put it in D or R, turn the wheel, and accelerate(i.e. leaving a parking spot) then the traction control light comes on, and I get a pulsing noise and shudder for about 3 seconds. During this, the car does not want to accelerate. Then the car drives normal. It doesn't do it unless the car has been sitting > 30 minutes. All the occurrences have been on pavement, and no slippage of the tires.

I had a GM reman Tranny put in in March of 2009, and then it was replaced again under warranty(I forgot why on the second time). It came with a 3 yr, 100,000 warranty.

Any ideas why it could be doing this?

The car has 135,000 on it, with the 3.8L. I drive spirited, but not abusive.
 

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Have you brought this to the attention of your local dealership? I can also look into this for you with your VIN. Please feel free to contact me by via private message. Thank you.

Tricia, GM Customer Service.
 

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pulsing and shudder are the abs/trac kicking in (most likely)
might bad a wheel speed senor going bad or a short in the line (common) telling it to kick in the trac
 

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Discussion Starter #4
Have you brought this to the attention of your local dealership? I can also look into this for you with your VIN. Please feel free to contact me by via private message. Thank you.

Tricia, GM Customer Service.
I thank you for your help, but my local dealership is a ripoff, and I refuse to do business with them.

Besides, I would imagine that I would have to take it to the shop that installed the transmission.
 

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Follow 04detroitls's post, he's right. The issue isn't going to have anything to do with the tranny. First check all 4 hubs, check the bearings for play (hehe, foreplay), and measure the resistances of each speed sensor. If the bearings are all ok, and the resistances are all the same, then replace the front wiring harnesses.
 

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Discussion Starter #6
It is hard to find a time when he isn't right.

I have replaced the left rear hub assy, because of a speed sensor, is the front pretty much the same?

What is the proper resistance for the sensor, and which prongs do you check across, I remember there being 3 or so.

In checking for play, IIRC, you jack it up, then grab the tire and try to wobble it, correct?

Thanks for the help guys.

Any tutorials floating around?
 

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I'm pretty sure there is a write up on replacing the front hubs, but it's pretty straight forward. I don't know off hand what the resistances should be, but they should all be the same, and they probably aren't all wrong. Try different pin combinations, if more than one combo gives a reading, use that on the others too, can't hurt. As for checking for play, that's about it. Just remember that a bearing will allow play in all directions, if it's only side to side that's a tie rod problem. If it's only top to bottom that's a ball joint issue.
 

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Discussion Starter #8
I'm pretty sure there is a write up on replacing the front hubs, but it's pretty straight forward. I don't know off hand what the resistances should be, but they should all be the same, and they probably aren't all wrong. Try different pin combinations, if more than one combo gives a reading, use that on the others too, can't hurt. As for checking for play, that's about it. Just remember that a bearing will allow play in all directions, if it's only side to side that's a tie rod problem. If it's only top to bottom that's a ball joint issue.
Thanks for that info. As soon as it isn't hot as balls out, I'll get it looked at.
 

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pulsing and shudder are the abs/trac kicking in (most likely)
might bad a wheel speed senor going bad or a short in the line (common) telling it to kick in the trac
My son's car was behaving similarly. And we had recently replaced the hubs with some new Timkens so I was pretty sure it wasn't them. I was afraid it was the wiring (or worse, in the ABS). I pulled the right front wire out from the hub back to the branch in the loom above the starter but saw no signs of damage, no limp kink in the wires. So I stuffed the wires back in the loom and rerouted them back to the right front hub.

I inserted and extracted the connector a few times trying to clean the contacts. Similarly, I pulled and reinserted the left front connector several times as well. Then I cleared the codes I was getting. (DTC C1221 LF Wheel Speed Sensor Input Signal is 0, DTC C1225 LF Excessive Wheel Speed Variation, DTC C1226 RF Excessive Wheel Speed Variation, DTC C1248 Dynamic rear proportion (DRP) )disabled)

The symptoms have not returned in the past ~6 weeks. My conclusion was that the connections were getting bad in the connectors and that that was causing the problem. While the connector housings are well made to seal things up (and keep out water), if the metal plating on the contacts is not perfectly compatible on both sides, galvanic corrosion can result in enough resistance to cause intermittent failures. Keep in mind, the signals in the speed sensors are pretty weak, so it doens't take much extra resistance to affect them.

In short, (@ OP) before you put new hubs on, try this first. Once you're done measuring the resistance in the sensors, insert and extract the connectors a few times to ensure they're making good contact. If the problem goes away, you might not need new hubs.

Doug

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My wife's 04 does the same thing, not all the time. It's not as bad in the past few weeks so screw it. I'm leaving mine alone.
 

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My son's car was behaving similarly. And we had recently replaced the hubs with some new Timkens so I was pretty sure it wasn't them. I was afraid it was the wiring (or worse, in the ABS). I pulled the right front wire out from the hub back to the branch in the loom above the starter but saw no signs of damage, no limp kink in the wires. So I stuffed the wires back in the loom and rerouted them back to the right front hub.

I inserted and extracted the connector a few times trying to clean the contacts. Similarly, I pulled and reinserted the left front connector several times as well. Then I cleared the codes I was getting. (DTC C1221 LF Wheel Speed Sensor Input Signal is 0, DTC C1225 LF Excessive Wheel Speed Variation, DTC C1226 RF Excessive Wheel Speed Variation, DTC C1248 Dynamic rear proportion (DRP) )disabled)

The symptoms have not returned in the past ~6 weeks. My conclusion was that the connections were getting bad in the connectors and that that was causing the problem. While the connector housings are well made to seal things up (and keep out water), if the metal plating on the contacts is not perfectly compatible on both sides, galvanic corrosion can result in enough resistance to cause intermittent failures. Keep in mind, the signals in the speed sensors are pretty weak, so it doens't take much extra resistance to affect them.

In short, (@ OP) before you put new hubs on, try this first. Once you're done measuring the resistance in the sensors, insert and extract the connectors a few times to ensure they're making good contact. If the problem goes away, you might not need new hubs.

Doug

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thanks doug. i cleaned out the connections and it seems to have worked for the time being. thanks.
 
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