2006 Chevrolet HHR 2.4 auto trans code P0751

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#1
I have a 2006 Chevy HHR with the 2.4 and an automatic transmission. I've been servicing it on the severe duty interval, so I had the transmission flushed for the second time about a week ago since it was at 100k miles. Last Tuesday I started getting a P0700 and a P0751, and it will not go into overdrive. When I clear the codes I get first gear back again but when it resets I only have second, third, and reverse. I had a new (and properly programmed) TCM sitting around, so I put it in in hopes of getting things working again. With the new one I again got the first three gears and reverse, but still no overdrive, and when the code set as a P0751 again it was back to second, third, and reverse again. Any advice on a fix for this? Thanks.
 
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#2
FLUSHED*- transmission, did the owners manual call for a flush?

Woould like to know more - who did it, where the manual mentions it, what fluid used.
To the best of my knowledge GM and other manufacturers do NOT recomend flushing, It is NOT in the owners manual and there have been TSB's advising not to do flushes...

* not a filter change and refill a POWER flush?
 
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#4
Wow that is going to spark some head scratching and debate...
As I remember they were strongly opposed...

They (GM) claimed the flush moved sludge thru the system accumulating in solenoids ... I will try to get one of the guru's to advise
 
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#5
??? Interesting - CW, was not to flush as the sludge may be driven under the pressure and create an issue such as P0751.. shift solenoid A stuck.

I see GM is now using FLUID EXCHANGE machines - a suttle differance that they make clear.

I am at a loss how to advise - :BeatsMe have you addressed the timing of this issue with your dealer?

A hail mary use the approxiate B&G trans fluid additive . as you drive to shop to discuss* ...may just may solve any sludge issue

*keep it a secret
 
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#7
I have yet to see sludge in an AT, but then I am only 73 years old, maybe tomorrow. Burnt fluid is more like it, leaves a carbon like deposit preventing mechanical movement.

Was your old fluid burnt? See on some newer vehicles, finally mounting an thermistor in the AT to detect an overheating condition, its about time.

If your old fluid was not burnt, could be an electrical problem as well, namely the so-called neutral safety switch loaded with those solenoid leads and/or the brake switch mounted above the brake pedal on making good contact. Grease on these gets rock hard so no long can make good contact, and not going into torque lockup or overdrive is a good sign of this problem.

Can never install a large enough AT cooler in these things, typically that six inch long piece of tubing in that hot radiator is nothing short of a bad joke. Torque converter is the key culprit in an attempt to compress AT fluid, really gets hot. In particular hitting that gas pedal hard in congested traffic with traffic light after traffic light, all red.
 
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#8
the term Sludge was used in it broadest interpitation..

maybe should have used accumulated shit is dislodged .
 

Gus

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#9
Sounds like a solenoid problem.....either sticking, bad, or harness to it.....
 
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#10
DTC P0751 appears to be a generic code where the test procedure varies with the particular transmission. Have to know the exact transmission in this vehicle for the proper test procedures. Sure Alldata.com explains this procedure for this particular vehicle. Least by getting it, would be on the right track.

I see on some GM transmission with both the code and the symptom, access to the troublesome solenoid and be accessed by simply dropping the pan. But didn't go further to search on a 2006 HHR 2.4L. Will leave that up to the poster.
 
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#11
It's a 4t45e transmission in there, and the dealer is saying it is simply a coincidnece, and I would be responsible for paying for the repair if they did it. If this one is a simple drop the pan and change it I'd definitely do that. While in there I'd also replace the filter sicne they didn't do that with the flush.

I put in some B&G, and with about 40 miles since I did that it's still giving the same code, even when I clear it out, and still not going to overdrive.
 
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#12
Well, it was the solenoid. It failed testing. Why ohh why did they put it there and NOT where you could get to in by removing the pan like normal? Ohh well, the car is doing great now, and I have even put over 1k on it since done!
 
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#13
Solenoids, basically a coil of wire wouldn't be a problem if they were layer wound and impregnated in a solvent based varnish. Was sometime in the late 70's the EPA banned solvent based varnishes and we had to switch to a water based varnish that did a terrible job of holding those coils together.

So just dropped that and went to a random wound coil pushed by bean counters to save even more time in production. Thermal expansion and vibration wears out what little enamel is on those wires, so they short out and you have problems. Other are in the lose unsupported wire terminations. So you wonder why we have problems? Sealed in a tin can so you can't see that sloppy work.

Was at Menards yesterday looking at air compressors, minding my own business, but a clerk came over to help me. Could only comment these made in China motors wouldn't last over a year, stator windings weren't even varnished, far worse with AC. Wonder why that is, China doesn't even have an EPA, must be for more profits. No excuse for this, we knew how to make stators and solenoids once.