I have GMC Envoy 2002. My Car is not going back when I put it in reverse gear. In addition, gear shifting is very delayed. Car is also not going above 3rd Gear. The mechanic says to overhaul the gear box, is it a possibility that some instruments might have malfunctioning like solenoid valve or so ..
I have GMC Envoy 2002. My Car is not going back when I put it in reverse gear?
- Thread starter Mech Man
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thebax2006
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If it's not moving in reverse but the forward gears still work you fried the reverse clutch pack and from the delay you describe it won't be long before the vehicle gets stranded and you have to tow it. The oil pump is going out and the pressures are off spec. By a rebuilt tranny.
Molson02536
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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 with a Transgo 0.490" boost valve (easy fix in pan).
Slow, slipping or no reverse: “lo-reverse” clutches are worn out, fluid leak in the reverse apply circuit, or broken sunshell. It is possible to remedy a fluid problem by removing the checkball from its cage in the case in the rear of the trans may help (must remove valvebody), or adding a high-viscosity additive such as Lucas Transmission additive or other seal restorer product. May also have worn boost valve (can replace in the pan).
1st and 3rd only, no 2,4 or R; sunshell is fractured or splines are sheared off. R&R. Try not to run or drive the car or further damage could result.
