Electrical issue
Thread Starter
Intermediate
Joined: May 2022
Posts: 41
Likes: 7
From: Shaler, Pa
Electrical issue
Hello all, I have a 2001 c5 that has been giving me some issues lately. When I try to start the car the coolant gauge will max out and the fuel gauge goes to zero followed by “reduced engine power” and occasionally other messages. There is also a buzzing noise from under the hood near the coil packs. I charged the battery thinking it was a low voltage issue but has still been present since. Any help is appreciated thank you
Thread Starter
Intermediate
Joined: May 2022
Posts: 41
Likes: 7
From: Shaler, Pa
Also lost control of the windows but got it back when I disconnected and reconnected the battery
Last edited by Dnacc5; Jul 15, 2023 at 09:44 AM.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,319
Likes: 3,927
From: Cape Coral, Florida
Sounds like the “classic” serial data bus issue…you will see the fuel gauge go to E, water temp gauge maxes out, power windows don’t work, and all all those DIC messages appear…what happens is one of the cars modules power or ground “back feeds” onto the single wire data bus and all heXx breaks loose…many times it’s the driver door connection inside of rubber accordion boot you see when you open the door…try shaking it a few times or pull the boot back and check the connector…if not that there are some other items we can check…if you have a DVOM that would be helpful…the data wire is pin #2 on the DLC and you can check if there is 12 volts or ground there when your problem occurs…I’ve actually demonstrated what you’re seeing by taking a jumper wire and putting 12 volts or a ground on that single data wire…won’t damage anything though…moving this to Tech.
https://www.youtube.com/live/f_NEEdgZSlE?feature=share
https://www.youtube.com/live/f_NEEdgZSlE?feature=share
Last edited by C5 Diag; Jul 15, 2023 at 09:52 AM.
Thread Starter
Intermediate
Joined: May 2022
Posts: 41
Likes: 7
From: Shaler, Pa
Sounds like the “classic” serial data bus…you will see the fuel gauge go to E, water temp gauge maxes out, power windows don’t work, and all all those DIC messages appear…what happens is one of the cars modules power or ground “back feeds” onto the single wire data bus and all heXx breaks loose…many times it’s the driver door connection inside of rubber accordion boot you see when you open the door…try shaking it a few times or pull the boot back and check the connector…if not that there are some other items we can check…if you have a DVOM that would be helpful…I’ve actually demonstrated what you’re seeing by taking a jumper wire and putting 12 volts or a ground on that single data wire…won’t damage anything though…moving this to Tech.
https://www.youtube.com/live/f_NEEdgZSlE?feature=share
https://www.youtube.com/live/f_NEEdgZSlE?feature=share
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,319
Likes: 3,927
From: Cape Coral, Florida
If the issue is not at the door connector you will need to check for 12 volts or ground at each of those 2 splice pack connectors near the BCM once you removed the “comb”…when the 2 combs are removed all the modules are isolated…you can then check for 12 volts or a ground on each wire with the key on…if this is something you want a professional to handle take the car to Danner Automotive in Bethel Park.
Thread Starter
Intermediate
Joined: May 2022
Posts: 41
Likes: 7
From: Shaler, Pa
If the issue is not at the door connector you will need to check for 12 volts or ground at each of those 2 splice pack connectors near the BCM once you removed the “comb”…when the 2 combs are removed all the modules are isolated…you can then check for 12 volts or a ground on each wire with the key on…if this is something you want a professional to handle take the car to Danner Automotive in Bethel Park.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,319
Likes: 3,927
From: Cape Coral, Florida
If you’ve never used a DVOM before I’d HIGHLY recommend you take the car to Danner Automotive and let them handle it…this diagnosis can get involved.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Thread Starter
Intermediate
Joined: May 2022
Posts: 41
Likes: 7
From: Shaler, Pa
probably a good idea. I’ll give them a call next week. Still gonna look at the connectors in the door, really hoping that fixes it
Thread Starter
Intermediate
Joined: May 2022
Posts: 41
Likes: 7
From: Shaler, Pa
Short update. Pulled out both connectors in the driver and passenger doors and checked for corrosion or loose wires with no luck. Moved on to the star connectors and disconnected the bar from both of them and the car still acts up. Is it possible that it’s a bad ground causing all these problems?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,319
Likes: 3,927
From: Cape Coral, Florida
It could be a bad ground but a ground for one of the modules…since you removed both “combs” and if with the key on all the modules are isolated you you shouldn’t see what you saw initially…if you jump the light green and dark green wires on the splice pack the car will start because the BCM and PCM need to communicate with each other.
Thread Starter
Intermediate
Joined: May 2022
Posts: 41
Likes: 7
From: Shaler, Pa
It could be a bad ground but a ground for one of the modules…since you removed both “combs” and if with the key on all the modules are isolated you you shouldn’t see what you saw initially…if you jump the light green and dark green wires on the splice pack the car will start because the BCM and PCM need to communicate with each other.
Thread Starter
Intermediate
Joined: May 2022
Posts: 41
Likes: 7
From: Shaler, Pa
Ok another update. Replaced ignition switch and tested the battery with no luck. Cleaned the grounds behind the headlights and the g104 grounds next to the battery. Checked grounds on the block on the passenger side and the driver side and both were tight and clean. The car will start if I jump the pcm and bcm. Anything else I can do before I take it somewhere?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,319
Likes: 3,927
From: Cape Coral, Florida
If you get that DVOM remove both “combs” and while probing each splice pack wire with the key on see if there is 12 volts or ground on any of those…a good reading will show as a voltage dancing around .2 to .3 volts.
Thread Starter
Intermediate
Joined: May 2022
Posts: 41
Likes: 7
From: Shaler, Pa
messed around with the multimeter today. Three of the wires on the first splice(brown, orange, brown/white) were going from 0 to .01. The purple wire was around .04. Not sure totally sure if I’m reading them correctly. Had the multimeter set to Volts and checked each female pin with the red lead
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,319
Likes: 3,927
From: Cape Coral, Florida