Truck going into "Limp mode"

Clay Keglovitz · Apr 19, 2016

1995 Chevy 2500 4x4 with 350TBI and 4L80E trans (I believe) Automatic approx 257K It had the transmission replaced from the previous owner at approx 200K

The truck went into limp mode a while back, would not go faster than 35 to 40 mph. Once I shut the truck off and drove it again later, it shifted just fine and drove normally.

I have not had the issue since and it has only happened the one time.

Does anyone know what the reason for this is and what can be done to prevent it from happening again?

meterman · Apr 19, 2016

mine was a bad battery low voltage will send it into limp mode

GL1500 · Apr 19, 2016

Same thing happened on my Ford 7.3 PSD while plowing. Had to let it charge a while, shut it off and when I restarted it all was good. It was a good lesson on learning not to have such happy hands with the plow controls. Soon after I replaced the alt with a hi amp unit and never had another problem.

1500z71 · Apr 20, 2016

Get your battery checked. Easy and probably free.

Clay Keglovitz · Apr 25, 2016

Thanks for the replies, I believe it is my battery(s) they are pretty old and get a lot of use with the boss plow.

RichLo · Apr 25, 2016

Yea, plows suck the juice fast, I have two alternators and two batteries in mine and its still struggles at times when I have the radio blasting and headlights on plowing short runs when I need to change plow direction often.

Clay Keglovitz · Apr 29, 2016

Yep for sure, Im just glad its not an actual transmission issue.

Jeff Davis · Jun 15, 2017

Did you get any codes when yours went in to limp mode? I think I'm having a low voltage problem also, but every time it starts limping, I get a shift solenoid code. Is that code thrown automatically because the lack of voltage is making the solenoids act up?

Supercharged111 · Jun 19, 2017

Could also be the harness inside the trans. I assume by limp mode you mean it only moves forward in 2nd gear? If so that's not a death sentence. Do report any codes observed.

Jeff Davis · Jun 20, 2017

Supercharged111 said:
Could also be the harness inside the trans. I assume by limp mode you mean it only moves forward in 2nd gear? If so that's not a death sentence. Do report any codes observed.

P0785 Shift Solenoid
I replaced those- didn't fix it.
Went back in a second time and replaced all the electronics and wire harness in the pan, replaced throttle position sensor- didn't fix it.
It will run perfectly when I first crank up, for a couple of miles to the first corner I make and when it shifts from there, it slams into second, dash light come on and limp mode the rest of the trip.
I had a brand new battery but it was bad and crapping out when this started, but only realized the battery was bad after I replaced everything. I thought maybe it was a voltage problem, but I have since replaced battery and cables and had the alternator checked out, but the problem is still there. I erase the codes, but every time I get that hard shift, the same code pops up again.

Truck going into "Limp mode"

Clay Keglovitz

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meterman

I'm Awesome

GL1500

I'm Awesome

1500z71

I'm Awesome

Clay Keglovitz

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RichLo

E I E I O

Clay Keglovitz

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Jeff Davis

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Supercharged111

Truly Awesome

Jeff Davis

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