95 Chevy 2500 in 'limp mode'

[masoncgy]

I have a '95 Chevy 2500 4x4, 5.7L auto, that I use for hauling materials and junk, has been a great runner, but this morning it has placed itself into 'limp mode' which basically restricts the truck to 2nd gear and reverse only, signaling an electrical problem of some sort.

Anyone else have a similar experience and able to guide me in the right direction of where to start testing?

Transmission fluid is filled and in good condition, truck itself runs and shifts smoothly, so I am not looking at an actual replacement of the unit itself, but of either a shift solenoid or sensor.

Any advice would be great! Thx!

[Benny]

Without doing any research: Check your air filter. On a few of the big Chevys at work that are always on dusty gravel roads, they go into limp mode when the air filter gets too clogged.

[anomaly2]

I would check for codes first, OBD 1 connector or OBD 2 ? Possible ignition switch not supplying power to fuses and defaults second gear.

[Unknown303]

Cycling the ignition a shit tonne of times should clear the limp mode. At least that works for the Duramax. I'd check the electrical connector to the transmission and the wires leading back. I had huge issues with my transmission once and it turned out I had shorted wire in the harness to the transmission.

[masoncgy]

I have it corrected for now, but I am still going to get underneath and check all of the wiring & connections, because that is my suspicion.

I disconnected the negative battery cable, left it for about 10 minutes, hooked it back up, went around the block and it's fine now, but definitely need to see if I can figure out where the problem may lie.

Great suggestions, keep 'em coming.

[corsvette]

Sounds like a shift solinoid going bad. Easy job on a 4l80E

[AE92_TreunoSC]

Don't clear the limp mode without finding out what caused it lol, you'll be stuck again the next time happens.

Get it scanned, try clearing it and go from there. Not knowing what caused it is crazy haha.

[Twin_Cam_Turbo]

I've seen on early 2000 1/2 and 3/4 ton GMs with those symptoms a problem with one of the wires in the ignition circuit that causes limp mode.

[CompletelyNumb]

Originally posted by corsvette
Sounds like a shift solinoid going bad. Easy job on a 4l80E


:werd:

Check that that wire on the top of the tranny is in good shape as well.

[masoncgy]

Originally posted by AE92_TreunoSC
Don't clear the limp mode without finding out what caused it lol, you'll be stuck again the next time happens.

Get it scanned, try clearing it and go from there. Not knowing what caused it is crazy haha.

For sure, but I wanted to absolutely rule out an actual mechanical condition with the transmission first, to conclude my suspicion that the issue was electrical in nature.

I have not been able to find anything on the exterior of the transmission, all wires, connecting points, etc look good, no corrosion or breaks in the lines, etc.

As mentioned, the shift solenoids appear to be a strong contender for replacement, so that is likely what will be occuring. It has been great since I did the reset, but we'll see how it goes.

I appreciate all of the advice, this is what I love about Beyond.

[heavyfuel]

I've had my Duramax go into limp mode because of a clogged fuel filter. Now I know yours is a gasser but Chevy is known for better fuel filtration and even though you don't have to change your fuel filter nearly as often in gas powered vehicles I'd have a look at that too.

[ExtraSlow]

Codes should tell you what part of the truck you need to be looking at. Could be any one of a hundred things, no point guessing until you read the codes.

Lots of people have code readers, and some auto parts stores will read them for you or lend the reader. I have one, but I'm a long way from Ladysmith, so that's not handy.

[Rat Fink]

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