i have a 96 jimmy...just hit 131,000 miles. a while back i took it to Reno from Northern Cal. the car did GREAT the whole way there and back. after i got home i realized it wasnt shifting properly. it still goes quite well but the RPMs rev until about 4,000 and pause for a few seconds and then go down. i dont know whats wrong and whatever it is its eating tons of gas!!!
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
1996 gmc jimmy shifting problems?
- Thread starter Tyler E
- Start date
Molson02536
New member
Before guessing at transmission problems, check the fluid level (car warmed up, engine running in Park on level ground) and have the PCM scanned for trouble codes FIRST.
Note that many problems that show up as transmission issues are actually PCM or electrical, and may be external to the transmission. Secondly, put a line pressure gauge (or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve (easy fix in pan).
1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace.
No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD and locks the converter : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.
No TCC lockup: Brake pedal switches improperly adjusted (always on), TCC solenoid failed (easy fix in the pan), TCC clutch worn out (must remove trans and replace TC).
These are a few things that i can think of which you have described, Soft shifting, gradual performance degradation: Poor line pressure rise due to leaking boost valve, clogged EPC filter screen, failing EPC solenoid, or worst case: leaky seals throughout. Transgo HD2-C kit fixes first two without removing trans. Seal restorer may fix last problem, but probably R&R Also try a transmission flush with BG brand products (Firestone stocks it) will clear the clogged EPC screen.
Start with the simple and check your transmission fluid level and condition. then move on to getting the Jimmy scanned for the DTC codes. I am leaning toward a faulty TPS (throttle Position Sensor) or a faulty Boost valve, or EPC valve. All are easy fix and any one of these parts are under $50.00.
Keep me posted, be glad to know you got your Jimmy running 100% again soon.
Note that many problems that show up as transmission issues are actually PCM or electrical, and may be external to the transmission. Secondly, put a line pressure gauge (or visit a local trans shop) on the pressure test port and go for a drive to verify proper line pressure. Base pressure at idle in P,N,OD should be around 70psi and around 140psi in R. Max line pressure should be at least 190psi at WOT in 1st or 2nd, 225psi is optimum. If base pressure is low, trans or pump is worn out. If max pressure is low, check EPC solenoid. If reverse is slow to engage, and line pressure does not come up to at least 130psi in reverse, replace the boost valve (easy fix in pan).
1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace.
No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD and locks the converter : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.
No TCC lockup: Brake pedal switches improperly adjusted (always on), TCC solenoid failed (easy fix in the pan), TCC clutch worn out (must remove trans and replace TC).
These are a few things that i can think of which you have described, Soft shifting, gradual performance degradation: Poor line pressure rise due to leaking boost valve, clogged EPC filter screen, failing EPC solenoid, or worst case: leaky seals throughout. Transgo HD2-C kit fixes first two without removing trans. Seal restorer may fix last problem, but probably R&R Also try a transmission flush with BG brand products (Firestone stocks it) will clear the clogged EPC screen.
Start with the simple and check your transmission fluid level and condition. then move on to getting the Jimmy scanned for the DTC codes. I am leaning toward a faulty TPS (throttle Position Sensor) or a faulty Boost valve, or EPC valve. All are easy fix and any one of these parts are under $50.00.
Keep me posted, be glad to know you got your Jimmy running 100% again soon.