1995 S15 Jimmy transmission problems

Jared · October 20, 2006

Ok, I've got a 95 Jimmy with the 4.3 Vortec and 4l60e transmission. This problem came and went and is now back again and I can't seem to figure out whats going on at all.

Whats happening is that the check engine light will come on and I will only have second and third gear, I also noticed that the truck does not compression brake either when I let off the gas.

I've had it scanned for codes but no codes are showing up even though the check engine light is on, we thought it was possibly my mechanics scanner so we disconnected the tps sensor to set a code and of course the scanner read it no problem, plugged the sensor back in and the scanner shows that the mil light is off even though it is on. So far I've replaced the ignition switch and the prndl switch on the side of the transmission to no avail.

Any input would be greatly appreciated, this is driving my mechanic and I nuts. Thanks in advance for your help.

GM-Tech · October 21, 2006

Sounds to me like you need to find someone with a better scanner. If it says the MIL is off when it's really on, something's wrong there.

It appears a trans code is setting and putting the tranny into it's default mode. You really need to look a little deeper for a code. Never saw a MIL light on that didn't have a code set. It could be a current code or just a history code (can his scanner view history codes?), but there should be a code.

Jared · October 21, 2006

Sounds to me like you need to find someone with a better scanner. If it says the MIL is off when it's really on, something's wrong there.

It appears a trans code is setting and putting the tranny into it's default mode. You really need to look a little deeper for a code. Never saw a MIL light on that didn't have a code set. It could be a current code or just a history code (can his scanner view history codes?), but there should be a code.

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His reads history codes as well and isn't coming up with anything. It's a hard fault because whenever I disconnect the battery the light is back on within 5 seconds of starting the truck up. His scanner is apparently a really good up to date scanner (its a Mac Mentor) but I'll try to get the truck scanned somewhere else.

Thanks for your help.

95Sierra2500 · October 21, 2006

If you're a '95, it's possible you have what is known as OBD 1.5, which alot of aftermarket scanners have difficulty reading. Might suggest you run to someone at a dealer and have them hook up a Tech II.