Transmission 'Thump' engaging first - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 General Tech Q&A > General

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  #1  
Old 08-08-2019, 12:59 PM
iceflow iceflow is offline
Junior Member
 
2005 Buick Rainier
Black 5.3L V8 2WD
Join Date: Jul 2011
Location: Houston, Texas
Posts: 77
Transmission 'Thump' engaging first

Folks,
I'm posting here as I think it will get more views:

Vehicle looked to lose 1st gear for about 5 miles or so, no speed take up even with pedal to metal. Then at a stop sign, engaged in 1st with a thump and ECL came on. Runs but thump engaging 1st and rough 'thump like' shift 1st to 2nd, after that it shifts ok. Reader has logged 12 ECL codes!!. I'm done with throwing money at vehicle and am thinking of dropping the pan and replacing both A & B solenoids and see if that fixes the issue. There is about 10K on the fluid though it was only a partial fluid replacement using Max Life. With that said, fluid in the tranny was only 30K miles old anyway. Nice pink color.
Here are the codes: thoughts, opinions, experiences on anything like this issue? I should add I have the ABS control module issue intermittent for years that is likely down to the dry solder joints problem in the ABS control pack.....which I need to pull and fix, so some of these codes may be due to that, with that said though when I get the 'ABS Service Brake System' display.....it never throws an ECL.


P0602 Control Module Programming Error
P0603 Internal Control Module Keep Alive Memory (KAM) Error
P0604 Internal Control Module Random Access Memory (RAM) Error
P0722 Output Speed Sensor No Signal
P0741 Torque Converter Clutch Circuit Performance or Stuck Off
P0751 Shift Solenoid A Performance or Stuck Off
P0756 Shift Solenoid B Performance or Stuck Of
P0757 Shift Solenoid B Stuck On
P0787 Shift/Timing Solenoid Low
P0973 OBD-II Trouble Code: Shift Solenoid A Control Circuit Low
P0974 – Shift Solenoid “A” Control Circuit High
P0977: Shift Solenoid “B” Control Circuit High OBD-II Trouble Code
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  #2  
Old 08-08-2019, 01:54 PM
mddombrowski mddombrowski is offline
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2006 Chevy TrailBlazer LT EXT
Summit White 4.2L I6 4X4
Join Date: Jan 2017
Location: Charlotte, NC
Posts: 195
Well slow down with the parts cannon because you'll run out of money before you run out of guesses. There's several non-transmission related things that can cause harsh shifting including a mis-calibrated TPS or a circuit fault in the ECT.

I suspect that you've got a control module issue going on here, but without access to some special equipment and an OEM level scan tool, this is going to be way outside of the scope of most driveway mechanics.

The most common cause of shift quality , excessive slipping, and delayed engagement issues are related to low fluid. My suggestion if you really want to "do something", is drop the pan and do a proper transmission service. If you drop the pan and there's debris and bits of a snap ring in the pan or inside the filter (cut it open) you can make your plans accordingly. If the fluid and filter look good then my recommendation would be to find a reputable shop and spend $100 for them to diagnose the problem. Then you can act on good information, but do not allow them to disassemble the transmission to give you a diagnosis. After disassembly, most other shops will no longer accept a transmission for repair. If they tell you they can't diagnose without disassembling, then you're in the wrong shop.
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  #3  
Old 08-08-2019, 02:26 PM
iceflow iceflow is offline
Junior Member
 
2005 Buick Rainier
Black 5.3L V8 2WD
Join Date: Jul 2011
Location: Houston, Texas
Posts: 77
Thanks for the response. My thoughts on parts replacement would be limited to the solenoids and anything in that price range. I'll check the fluid level, I actually checked it just a few weeks ago and it was fine but I'll check it again, haven't noticed any leaks. At this point I'm just trying to see if I can get an inexpensive fix and if I do a service and drop the pan I believe the solenoids are right there? Also I'll check price on Transmission Output Speed Sensor, though I don't know where that is located.
What I could do I guess is drop the pan, open the filter as you suggest and if there's metal in there then no need to go further. I won't be spending hundreds of bucks on this vehicle.
So it sounds like a decent shop, which I know of one, could skinny down the likely cause from the 12 codes? I might go that route, I'll noodle on it for a while.

Thanks!
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  #4  
Old 08-08-2019, 03:53 PM
mddombrowski mddombrowski is offline
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2006 Chevy TrailBlazer LT EXT
Summit White 4.2L I6 4X4
Join Date: Jan 2017
Location: Charlotte, NC
Posts: 195
Depends on how much a "maybe" is worth to you. To replace all three shift solenoids plus the pressure control solenoid is going to be about $50 a pop unless you get cheap aftermarket junk, plus fluid, filter, and pan gasket, and whatever your time is worth... and when it doesn't fix the problem, then what? Now you're out $200-$250.

If a customer brought this car to my shop, my recommendation would be to leave it with me. Pay me an hour to diagnose it. At the end of the hour I'll know what the issue(s) is(are). Part of my diagnostic routine would be to clear the codes and go on a test drive and see what codes return (of course I'll have saved them for future reference before I cleared them).
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  #5  
Old 08-08-2019, 04:11 PM
iceflow iceflow is offline
Junior Member
 
2005 Buick Rainier
Black 5.3L V8 2WD
Join Date: Jul 2011
Location: Houston, Texas
Posts: 77
Yep, good input. I might be going full circle on my thoughts. I did have it scheduled to go to Buick tomorrow for a 99 dollar diagnosis. I did cancel that but I could reschedule.

Thanks
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