Misbehaving Tranny - Hope For Easy Fix

masodo · May 25, 2017

2000 GMC Sonoma SLS Ext Cab 2.2L 134CI L4 FI 4L60E

For the last couple of months I have been seeing my ABS light coming on (usually after hitting a sharp bump in the road) and occasionally while the yellow ABS light is on the red BRAKE light will flash briefly and the speedometer will pulse erratically (if the cruise control is on it will disengage when the speedo flakes out.) If ever I shut down the engine and restart the ABS light always goes out after just a few revolutions.

Yesterday while merging onto the interstate I found that the transmission would not properly downshift on acceleration. The transmission did just not want to engage... I finally coaxed it into traffic by feathering the throttle but as soon as I slowed down (because of stop and go traffic) whenever I would accelerate the engine would just rev with no engagement in the tranny. I soon discovered that I could manually shift into 2nd gear to get a move on and then manually shift into 3rd followed by Drive and all was good until I would have to slow again and would have to repeat the process to get going again.

The conditions were damp roadways but I have not been through standing water and there is no SES light. Once I finally made it home and parked in the spot where it now sits I placed it in park and thought I felt a 'thump' when I did, so I - with foot on break of course - went from Park to Drive to Reverse and did get a pretty healthy 'ca-thunk' somewhere in there. I put it back in Park and shut her down. After reviewing this forum I am pretty confident I need to look at wiring issues but still need to research all that business. I had thought if I could not fix this by cleaning and jiggling I would look into the likelihood that this might be something I could fix myself on the ramps and pulling the transmission pan. Worst case scenario I would take it to a mechanic for a no doubt painful diagnosis.

I just wanted to throw this out there in case anyone has blazed this trail before me. Any help would be greatly appreciated.

masodo · Jun 30, 2017

Problem Solved

Man, it sure would have been nice if some kind member of the GMC Owners forum would have chimed in here with some sage advice or offered the often overlooked little factoid that could solve most transmission problems with little more than a YouTube video and a pair of pliers... but that was not to be.

I just wanted to come back and leave a follow-up so nobody thinks the jack-stands must have failed and I met my maker with the imprint of a differential in my right cheek...

So yeah, it was a worst case scenario... took it to the mechanic and he threw a used transmission at it. $1400 later - problem solved!

Misbehaving Tranny - Hope For Easy Fix

masodo

New member

masodo

New member

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