transmission shifts hard

60

Asked by Jun 17, 2015 at 05:17 PM about the 2001 GMC Sierra 1500 SLT 4WD Extended Cab LB

Question type: Maintenance & Repair

5.3 L engine (from 2002 Silverado) with a 4l80e transmission shifting hard from 1st to 2nd
gear. All other gears shift normal

17 Answers

88,985

Could be the solenoids. When was the trans serviced last? You might want to take it by a parts store that can check the codes, look for any transmission codes in the memory, hopefully there will be some there and that would give you some place to start.

1 out of 1 people think this is helpful.
60

Did the parts store thing and no codes. Filter and fluid changed 2+ years ago. It looks clean on the dipstick. Read somewhere it might be the TPS (Throttle Position Sensor) so I'm going to try to check that out tomorrow. Ever hear of that?

88,985

It is possible that the throttle plate could be dirty and throwing off the initial setting, have you cleaned the throttle body lately? Usually if the TPS is bad it will throw a code, but I have seen TPS sensors have a brief open in them that the ECM will not pickup on.

1 out of 1 people think this is helpful.
60

I plan on cleaning the throttle body before changing the TPS. I'll let you know what happens. Thanks

1 out of 1 people think this is helpful.
60

Cleaning TPS/body didn't work. Still not getting any codes except Mass Air Flow sensor voltage high. Could that be it?

88,985

Clean the air flow sensor also, check the minimum air rate, reset if needed, then reset the ECM and roadtest if the check engine returns with the same code, check the ECM's sensor voltage to that sensor, if the ECM's voltage is at 5 volts or just slightly below at the sensor then check the sensor ground if it checks good then replace the sensor.

1 out of 1 people think this is helpful.
Best Answer
60

Thanks shoes. I tried cleaning the sensor and didn't help. I'll try resetting PCM and see what happens

2 out of 2 people think this is helpful.
60

Found problem. Broken wire from PCM to transmission shifter (connector on top of shifter) ground wire broken and power wire barely hanging on. Ops check good.

2 out of 2 people think this is helpful.
60

Soo much for "experts" at AAMCO and McCarthy's transmissions in Newport News Virginia. Told me it needed rebuild and or replacement. CROOKS!

1 out of 1 people think this is helpful.
88,985

Glad you found the problem, that seems to be the problem with a lot of the major repair places, just jumping to conclusions with out doing a full diagnostic first. I have found through the years that poor grounds and power supplies cause more problems than actual component failures. But that still don't explain the air flow code unless it's ground was at the same location.

1 out of 1 people think this is helpful.
60

Mass Air Flow sensor is "disconnected" by my son-in-law. He has some kind of "electronic tuner program" (hooks to his laptop). He has that and 2 O2 sensors disconnected (no catalytic converter installed). I have him sending me the program and cable now so I can figure out hopw to tune up the truck. New fangled gadgets drive me crazy.....lol. Thanks for your help

I have a 2000 that shifts hard 1-2 only sometimes idk what it is

88,985

acborden that sounds like the same most everyone is having with the sticking shift solenoids.

What is PCM?

3,425

Powertrain Control Module ATM

3,425

Hello, Broken Accumulator Spring or Piston, sticking piston, in the valve body. Hope this Helps, ATM

Ok thanks. Doing work on my 2001 GMC Sierra 1500. If i floor it, it takes forever to shift gears. Rpm jumps up to 6 and sticks for about a minute unless i come off the accelerator. I know my throttle body could use a good cleaning but i also get a small evap leak code. Having a hard time locating that. When i get up to 80mph or if i floor it i get this strong odor through the ventilation system that smells like a mix of oil and gas. When i bought the truck and changed spark plugs i noticed an oil like moisture on the back end of about two plugs that had that same smell. I was told that it could be some valve and ring could need replacing along with check to see if catalic converter is clogged. Just started doing work on my own vehicle so idk any of the mechanic jargan as you can tell...lol.

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