C5 Limp mode

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Sep 30, 2022 | 04:59 PM

jerrybags

Thread Starter

Heel & Toe

Joined: Feb 2015

Posts: 18

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C5 Limp mode

Have been experiencing 'occasional' limp modes which reset after off/on cycle. Code first indicated TPS and Throttle Body issues. I replaced both with new (very hard to find) parts but the Limp problem exists.

Also, the clock loses its time setting.

Thoughts on diagnosing? Anyone with this problem?

Could this be an electrical issue? Harness / connection issue?

Thanks for any help... Jerry

Oct 1, 2022 | 10:22 AM

Dudly Doright

Instructor

Joined: May 2008

Posts: 174

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From: Pahrump NV.

I would start with cleaning all the chassis Grounds on the car
Then inspect engine harness carefully.

Oct 1, 2022 | 01:24 PM

Dads2kconvertible

Melting Slicks

Joined: Sep 2021

Posts: 2,555

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Quote:

Originally Posted by jerrybags

clock loses its time setting.

That indicates loss of electrical power to me. Any corrosion under the battery tray as described here: https://www.corvetteforum.com/forums...and-a-fix.html

Dec 22, 2022 | 05:37 PM

jerrybags

Thread Starter

Heel & Toe

Joined: Feb 2015

Posts: 18

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C5 Limping

Thanks everyone for weighing in on solutions to this occasional limping issue. Much appreciated.

Now after taking the car into 4 different shops, including a Chevy dealership, nobody could identify the source of the problem. One of you indicated it might be a power issue. Well I 'limped' into a nearby one-man shop and after much ado and discussion, he cleared the entire code history. Then when I told him about the clock going whacko every time it limped, he too said it must be a power issue not a mechanical one. So we replaced the battery and he pulled the connecting cables and gave them a good scrub and put it all back.

I've now driven 8 hours and 200+ miles and... NO LIMPING!

I can only think the other shops were following the error codes referring to throttle body issues (which I had replaced) and it was leading them down the wrong path and they ended up chasing their tails. They really didn't think out of the box.

So thankful for the new shop I'll be using. Thousand+ $$ and 10 months of nonsense cured by a battery change.

Who'd a thunk?

Jerry

Dec 22, 2022 | 07:55 PM

C5 Diag

Moderator, Tech Contributor

Joined: Sep 2013

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From: Cape Coral, Florida

Well you NEVER diagnose based on the codes !!… there can be a few problems that can throw a “Reduced Engine Power”….shops or dealerships are bad at diagnostics anyway…if it returns let us know !!

Jan 1, 2023 | 10:49 AM

jerrybags

Thread Starter

Heel & Toe

Joined: Feb 2015

Posts: 18

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Well after 11 hours of driving and 300 miles I thought I was done with it. NOT! Went limp again yesterday in the rain. Haven’t really addressed it as yet. Tired of this unpredictable nonsense.

Jan 1, 2023 | 11:55 AM

C5 Diag

Moderator, Tech Contributor

Joined: Sep 2013

Posts: 15,430

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From: Cape Coral, Florida

Does your new found mechanic use a scope ??…if he doesn’t he will only be guessing too !!…find yourself a “diagnostic” shop or an auto- electric shop…these guys use scopes everyday…they will find your issue….if it’s still TPS codes you’re seeing the slightest drop out in voltage will cause the car to go into limp mode….you won’t see this with a voltmeter…a scope takes millions of voltage readings per second.

Last edited by C5 Diag; Jan 1, 2023 at 01:01 PM.

Jan 1, 2023 | 12:59 PM

C5Mat

Instructor

Joined: Oct 2020

Posts: 139

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Have you tried cleaning the MAF sensor? Might not be it but it is tied to the throttle for some reduced power codes and simple to do. Was there corrosion on//under the battery tray?