No comm message in DIC for everything
Thread Starter
Racer
Joined: Apr 2007
Posts: 452
Likes: 50
No comm message in DIC for everything
Hello all,
Need help PLEASE!
2002 ZO6 parked outside in some very cold weather. When I tried to start it battery was dead. Hooked up 15 amp battery charger and got battery back up to 12.7 volts. Now when I try to start I get service soon message and all the sections in the DIC codes, pcm, TCS, etc…. All show no comm. The fuel pump is not coming on, door locks and windows don’t work either. Checked pcm and bcm fuses and they are good. I pulled the pcm and installed a good used one but that did not fix it.
Could the BCM be bad ?
Any help would be greatly appreciated.
Need help PLEASE!
2002 ZO6 parked outside in some very cold weather. When I tried to start it battery was dead. Hooked up 15 amp battery charger and got battery back up to 12.7 volts. Now when I try to start I get service soon message and all the sections in the DIC codes, pcm, TCS, etc…. All show no comm. The fuel pump is not coming on, door locks and windows don’t work either. Checked pcm and bcm fuses and they are good. I pulled the pcm and installed a good used one but that did not fix it.
Could the BCM be bad ?
Any help would be greatly appreciated.
Last edited by Pipedream; Jan 25, 2025 at 01:27 AM.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,621
Likes: 4,069
From: Cape Coral, Florida
You can follow this procedure:
1) Locate the 2 Star Connectors to the left of the BCM and remove the buss bar or “comb” from star connector #2…it has 4 wires on it…see if the car starts…if no start go to next step.
2) Now remove the comb off the other star connector leaving both combs removed…make a jumper wire and jumper the BCM to PCM…light green to dark green wire….if car starts you have a module other than the BCM and PCM on star connector #1 pulling the data bus down….if car still doesn’t start the module pulling the bus down is either the BCM or PCM…go to next step.
3) Take your jumper wire and connect from the purple wire (data bus wire) to the PCM (dark green wire)…now with your scan tool see if you can communicate with the PCM…if you can now communicate the PCM is good and issue may be the BCM…to see if the BCM is indeed bad take the jumper wire and connect the jumper now to the BCM (light green)…with a scan tool that can communicate with ALL modules (NOT a code reader) and if you can’t communicate we can “assume” BCM is bad…for single module “no comm” you want to check the powers and grounds to that module.
1) Locate the 2 Star Connectors to the left of the BCM and remove the buss bar or “comb” from star connector #2…it has 4 wires on it…see if the car starts…if no start go to next step.
2) Now remove the comb off the other star connector leaving both combs removed…make a jumper wire and jumper the BCM to PCM…light green to dark green wire….if car starts you have a module other than the BCM and PCM on star connector #1 pulling the data bus down….if car still doesn’t start the module pulling the bus down is either the BCM or PCM…go to next step.
3) Take your jumper wire and connect from the purple wire (data bus wire) to the PCM (dark green wire)…now with your scan tool see if you can communicate with the PCM…if you can now communicate the PCM is good and issue may be the BCM…to see if the BCM is indeed bad take the jumper wire and connect the jumper now to the BCM (light green)…with a scan tool that can communicate with ALL modules (NOT a code reader) and if you can’t communicate we can “assume” BCM is bad…for single module “no comm” you want to check the powers and grounds to that module.
Thread Starter
Racer
Joined: Apr 2007
Posts: 452
Likes: 50
Thank you for the reply. I will definitely keep all of that information in my local how to notes.
I pushed the car into the garage last night to keep from freezing while I was working on it. I finally gave up around midnight. The car usually sits outside. I went down this morning and everything was working windows fuel pump, all of the no comm messages are gone. I cleared the codes and the car started right up.
wth???
I pushed the car into the garage last night to keep from freezing while I was working on it. I finally gave up around midnight. The car usually sits outside. I went down this morning and everything was working windows fuel pump, all of the no comm messages are gone. I cleared the codes and the car started right up.
wth???
Tech Contributor
Joined: Jan 2007
Posts: 19,470
Likes: 1,171
From: Dyer, IN
You cannot just swap in any C5 PCM. Even if you did swap in a known good used 2001-2004 PCM it's not going to work without some setup steps. Install the original PCM...and proceed with your troubleshooting.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,621
Likes: 4,069
From: Cape Coral, Florida
Thank you for the reply. I will definitely keep all of that information in my local how to notes.
I pushed the car into the garage last night to keep from freezing while I was working on it. I finally gave up around midnight. The car usually sits outside. I went down this morning and everything was working windows fuel pump, all of the no comm messages are gone. I cleared the codes and the car started right up.
wth???
I pushed the car into the garage last night to keep from freezing while I was working on it. I finally gave up around midnight. The car usually sits outside. I went down this morning and everything was working windows fuel pump, all of the no comm messages are gone. I cleared the codes and the car started right up.
wth???
Unfortunately you can’t diagnose it if it’s not acting up !!
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,621
Likes: 4,069
From: Cape Coral, Florida
Hello all,
Need help PLEASE!
2002 ZO6 parked outside in some very cold weather. When I tried to start it battery was dead. Hooked up 15 amp battery charger and got battery back up to 12.7 volts. Now when I try to start I get service soon message and all the sections in the DIC codes, pcm, TCS, etc…. All show no comm. The fuel pump is not coming on, door locks and windows don’t work either. Checked pcm and bcm fuses and they are good. I pulled the pcm and installed a good used one but that did not fix it.
Could the BCM be bad ?
Any help would be greatly appreciated.
Need help PLEASE!
2002 ZO6 parked outside in some very cold weather. When I tried to start it battery was dead. Hooked up 15 amp battery charger and got battery back up to 12.7 volts. Now when I try to start I get service soon message and all the sections in the DIC codes, pcm, TCS, etc…. All show no comm. The fuel pump is not coming on, door locks and windows don’t work either. Checked pcm and bcm fuses and they are good. I pulled the pcm and installed a good used one but that did not fix it.
Could the BCM be bad ?
Any help would be greatly appreciated.
It could be any module pulling down the serial data bus.
Melting Slicks
Joined: Sep 2008
Posts: 3,138
Likes: 802
From: Espanola New Mexico
So unfortunately this problem may occur again, the no comms maybe as simple as a bad electrical connection between the door and car. There are two connectors inside the rubber accordion that develop bad electrical contacts after years of door openings, if the problem reoccurs try shaking the accordion tube.
Last edited by mmartinez; Jan 25, 2025 at 05:24 PM.
Thread Starter
Racer
Joined: Apr 2007
Posts: 452
Likes: 50
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
