we own a 96' gmc sierra the truck has been look after very very well has 300,000+ kilometers and is still running great i had in my school shop awhile back and look over it everything in the steering is good same with exaust and motor shape still silent, we replaced the tranny about a two years ago but hey they wear out, anyhow once the truck is warmed up the check engine light comes on and after that the tranny starts to clunk (hard shift) slowing down and speeding up, i had a hand held computer pluged into the truck, a good one at that, and it could tell the light had been on but could not figure out the problem or what was wrong. another thing this does not always happen but we would like to get rid of it so if you have any idea what the problem is please tell.
1996 gmc sierra engine light, hard shifting?
- Thread starter Colin
- Start date
Molson02536
New member
1. Extremely harsh shifts from P or N, normal shifts at WOT: EPC (Electronic Pressure Control) solenoid failed. Easy fix in pan. Fix as soon as possible or hard parts will eventually break.
2. Shift suddenly become very hard. When going from park to either reverse or drive it slams into gear. 1-2 and 2-3 shifts are also harsh. All gears seems to work. Problem may be intermittent: Check TPS for smooth electrical response. If the response is jumpy or erratic at all, replace TPS.
Start with these simple things to check and keep us posted, good luck.
Possible Problem
I have the same problem with a 1995 GMC 1500 Z71 that I just bought - Has 244,xxx miles on it. They tranny would shift hard from 1-2, there was not problem in any other gears.
Then while driving truck it started to jump between gears.
After going through a ton of threads online (this is my first truck) and consulting with a GM tech. I found that the most likely problem was the ignition switch needed to be replaced, this causes check engine light and ABS light to come on and it messes with tranny performance.
Just something to consider.
I have the same problem with a 1995 GMC 1500 Z71 that I just bought - Has 244,xxx miles on it. They tranny would shift hard from 1-2, there was not problem in any other gears.
Then while driving truck it started to jump between gears.
After going through a ton of threads online (this is my first truck) and consulting with a GM tech. I found that the most likely problem was the ignition switch needed to be replaced, this causes check engine light and ABS light to come on and it messes with tranny performance.
Just something to consider.