Edmunds Answers



  • alaskanj 02/26/10 4:54 pm PST

    wouldnt hurt to double check the fluid level follow the instructions on how to do it either in the owners manual or on the trany dip stick its either at operating temp with trany in neutral or park or it might even be while cold.. If thats not the problem bring it to the place that seviced it, tell them what is happening after the fact.....

  • morin2 02/26/10 5:36 pm PST

    Its been 18K since the tranny service. Did it whine & shift hard right after the service or is this a recent thing? Burnt or low fluid can produce hard shifts. Pull out the AT dipstick after driving for a while and examine the color, smell, and level (follow owner's manual instructions for checking fluid - best is with engine running, in Park and after going thru all the gears).

    Do not get a trans "flush". If you want to replace the fluid, just do a drain & refill & filter, not a flush. If you do it yourself, you'll only be draining the torque converter and replacing about 25-30% of the fluid. If the fluid is bad, do this every few months, eventually bringing the fluid to mostly new, until the fluid is nice & pink.

  • nittanylion_84 02/26/10 5:54 pm PST

    Not sure how to respond to responses, so here goes. It has been doing this pretty much since the service. Had it done at a friend's shop, so have been reluctant to go back to him to point out the error. Need to get over that, I guess.

    I did check the fluid right after the servicing. A tad low, but not much at all. Will check again.

    GMs tend to have problems with alternators; any chance mine is going bad, pushing too much juice into the ECM and other electronics and causing this problem?

    Another buddy just mentioned the serpentine belt as a possibility. He's a smart guy, but has never owned a GM, to my knowledge. But, any chance he is on to something?


  • karjunkie 02/26/10 5:57 pm PST

    A common problem with the 4T65E transaxle is the pressure control solenoid (PCS) causing the hard shifting and in most cases upshifts only. If this is the case with yours then a scan with a trans capable scan tool may reveal a stored DTC of P1811 (max adapt, long shift) which would confirm the PCS is suspect. High probability it is a PCS related issue especially with the combination hard shifts and whining sound. When a P1811 DTC (max adapt, long shift) sets it commands high line pressure (max) and disables shift adapts. As a result you get the hard/harsh shifts and the whining sound from the pump. This repair will run about $600, so before going to that expense I would try to clean out the valve body with Seafoam Trans Tune first. Leave it in for about a week or two of driving. Then do a fresh fluid and filter change making sure you use Dexron VI fluid. You'll be quite surprised how much varnish the Seafoam will wash out. The transaxle will possibly start to shift smoothly after the first week, but it should have the fluid changed to remove the gunk that will be dissolved.

  • morin2 02/26/10 6:02 pm PST

    If it was a tad low 18K miles ago, it did not increase its level on its own since then. Drive the car for a while, then park it on a level area, go thru all the gears, put it in Park and check the fluid with the engine running. Look for no burned smell, nice pink color, and the exact level. Its critical that the level is exactly correct. A tad low is a problem for a transmission.


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