Car not starting - bad PCM?
Thread Starter
3rd Gear
Joined: Nov 2022
Posts: 2
Likes: 1
Car not starting - bad PCM?
Hello! 2005 Z71 owner. 35k miles on car. Took it out of storage and it would not start. Changed the battery, new spark plugs. Checked the gas. Nothing. Had it towed to Chevy dealer who said PCM bad. Couldn't learn the keys when trying to program. Could not even get accessory button to work. They have had it 6 months now. Can't figure it out. You can't get an OEM PCM because discontinued.. The aftermarket PCM would not work either. Suggestions?
Drifting
Joined: Apr 2016
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From: DFW Texas
Safety Car
Joined: Dec 2006
Posts: 4,592
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From: Pearland / Houston Tx
If I am not mistaken, A PCM (powertrain control module...thought that was a Chrysler/Jeep component) combines engine and transmission controls in one unit, while GM uses separate ECM (engine) and TCM (transmission) modules.
Don't believe the C6 has a PCM. If I am correct, hope you trust the dealer who told you that you have a bad PCM.
Don't believe the C6 has a PCM. If I am correct, hope you trust the dealer who told you that you have a bad PCM.
Thread Starter
3rd Gear
Joined: Nov 2022
Posts: 2
Likes: 1
C6ToGo - he dropped the terms OEM, PCM, ECM and BCM. Whatever it is, they told me they didn't know what the problem is or the next steps. Since I bought it from them 16 years ago and they serviced it routinely, I don't know what to do.. which is why I'm on here. Hoping someone had a solution or advice. Thank you.
Drifting
Joined: Dec 2016
Posts: 1,389
Likes: 220
lights come on? how do you open the doors? have you tried the glove compartment spot + keyfob?
*edit* sorry. 2005, not sure if it has that slot for the keyfob since i think its set up differently. Does the key still have the VATS? do you have access to a tech 2 or HPtuners?
HPtuners to remove VATS, tech2 to see what code its throwing, assuming the ECM/whatever is getting power...
*edit* sorry. 2005, not sure if it has that slot for the keyfob since i think its set up differently. Does the key still have the VATS? do you have access to a tech 2 or HPtuners?
HPtuners to remove VATS, tech2 to see what code its throwing, assuming the ECM/whatever is getting power...
Pro
Joined: Apr 2008
Posts: 728
Likes: 30
From: Paris
Hi,
As usual, if you don't provide the list of DTC, everyone will be shooting in the dark.
I had an issue with the ECM recently and explained what I did.
But I pulled codes and assessed which harness & component were acting up.
i concur with others, the vette doesn't have a PCM. It has an ECM and TCM
As usual, if you don't provide the list of DTC, everyone will be shooting in the dark.
I had an issue with the ECM recently and explained what I did.
But I pulled codes and assessed which harness & component were acting up.
i concur with others, the vette doesn't have a PCM. It has an ECM and TCM
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,631
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From: Cape Coral, Florida
C6ToGo - he dropped the terms OEM, PCM, ECM and BCM. Whatever it is, they told me they didn't know what the problem is or the next steps. Since I bought it from them 16 years ago and they serviced it routinely, I don't know what to do.. which is why I'm on here. Hoping someone had a solution or advice. Thank you.
Last edited by C5 Diag; Nov 19, 2022 at 08:35 AM.
Race Director
Joined: Oct 2004
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Ms K, sorry to hear the car isn’t starting….Dealerships when they have no clue always say “it’s a bad PCM/ECM”…my C5 it’s a PCM…your car an ECM…just nomenclature…I guess they already changed the ECM without success so there proves my point…your first big mistake was taking the car to a dealership for a diagnosis…6 months there and they could not figure it out…LOL ??….dealerships do NOT have the expertise to diagnose cars…they only know how to change parts and that can get expensive for you….you’ll need to find a purely “diagnostic” shop or even an auto-electric repair shop in your area because they have the electrical knowledge required to repair these cars…where are you located ??…I know of these shops scattered throughout the country…if it’s a no crank no start other than being an issue in just the starting circuit it can be a communication issue (GM LAN) which requires the use of a labscope which dealerships do not use…labscope is necessary…a defective module…ECM, TCM, BCM can cause a no start or ANY other module…a video below so you can see what’s involved in this kind of diagnosis….99.99% of shops don’t have the skills required for this !!
https://youtu.be/OHK8vQI5WSQ
https://youtu.be/OHK8vQI5WSQ
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Race Director
Joined: Oct 2004
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If I am not mistaken, A PCM (powertrain control module...thought that was a Chrysler/Jeep component) combines engine and transmission controls in one unit, while GM uses separate ECM (engine) and TCM (transmission) modules.
Don't believe the C6 has a PCM. If I am correct, hope you trust the dealer who told you that you have a bad PCM.
Don't believe the C6 has a PCM. If I am correct, hope you trust the dealer who told you that you have a bad PCM.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,631
Likes: 4,076
From: Cape Coral, Florida
You're right Rob. They may be OK diagnosing cookie cutter, minor problems, but that's probably giving them more credit than I should. Another good friend of mine, who was a lifelong auto mechanic/technician now living in Arizona, sounds just like you! He said there's very few really mechanically inclined true mechanics around anymore. The majority throw parts (and our $$!!) at the problem until they fix it, IF they do, then say they nailed it, LOL!! Best ones are in specialized auto electric shops, or engine/trans/driveline shops, and are called "specialists." 6 months at ANY repair facility is outrageous!! You can build most of a HOUSE in 6 months. Sounds like a dandy stealer......
Like I’ve said a MILLION or more times here there a few good diagnosticians…dealerships and general repair shops don’t make money diagnosing so that’s why they’ll do…just fire the parts canon…6 months is outrageous !!…most electrical issues should be handled by an auto-electric shop.
Race Director
Joined: Mar 2010
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From: T-Town WA
2016 C6 of Year Finalist
Hello! 2005 Z71 owner. 35k miles on car. Took it out of storage and it would not start. Changed the battery, new spark plugs. Checked the gas. Nothing. Had it towed to Chevy dealer who said PCM bad. Couldn't learn the keys when trying to program. Could not even get accessory button to work. They have had it 6 months now. Can't figure it out. You can't get an OEM PCM because discontinued.. The aftermarket PCM would not work either. Suggestions?