Trying to find a common denominator
Thread Starter
3rd Gear
Joined: Jan 2021
Posts: 3
Likes: 0
From: NC
Trying to find a common denominator
I enjoy reading through the information on these forums but haven't seen anything about my current situation. I have tried a couple very knowledgeable mechanics one even a former GM tech can't get my answer. Abbey (my Vetts name) does this funny thing. Driving down the road out of the blue Traction control light Abs light comes on. Normal right it's a C5?! But get this the AC or heat which ever is on goes out. No display no blower nothing. Stays off maybe a few days. Low and behold get in start her up. Everything is fine no problems. Day or so later out again. I have explained this and people tell me there is no connection between AC and Abs but there has to be something !! Done the ground thing. Even disassembled them. Actually looked good for a 22 year old girl! I am at a loss... Advice is appreciated Thanks
Le Mans Master
Joined: Jul 2010
Posts: 6,012
Likes: 726
I enjoy reading through the information on these forums but haven't seen anything about my current situation. I have tried a couple very knowledgeable mechanics one even a former GM tech can't get my answer. Abbey (my Vetts name) does this funny thing. Driving down the road out of the blue Traction control light Abs light comes on. Normal right it's a C5?! But get this the AC or heat which ever is on goes out. No display no blower nothing. Stays off maybe a few days. Low and behold get in start her up. Everything is fine no problems. Day or so later out again. I have explained this and people tell me there is no connection between AC and Abs but there has to be something !! Done the ground thing. Even disassembled them. Actually looked good for a 22 year old girl! I am at a loss... Advice is appreciated Thanks
So if i was u, go back and put ur glasses on. Then u will get a different perspective on how corroded it can be and if it looks good still take the wires or plugs apart . THis is what i would do but me do what u want.
Melting Slicks
Joined: Jul 2004
Posts: 3,294
Likes: 482
From: Brea CA
There is a common item between these components. The serial data bus is common to all modules.If there is a break in connection or short to power or ground you will have issues.
A common spot for this to be an issue is in the wiring harness between the door and a pillar. This can happen on both sides.
Worst case is that there is a problem with the BCM in the passenger foot well. The BCM controls the power on/off for some of the modules along with the factory radio. It controls these over the serial data bus.
Gary
A common spot for this to be an issue is in the wiring harness between the door and a pillar. This can happen on both sides.
Worst case is that there is a problem with the BCM in the passenger foot well. The BCM controls the power on/off for some of the modules along with the factory radio. It controls these over the serial data bus.
Gary
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,591
Likes: 4,055
From: Cape Coral, Florida
There are several different colored wires that come out of the ignition switch and feed certain circuits in the car...the HVAC module and EBCM are both fed from that particular circuit...I'd suggest looking at the ignition switch...if you know your way around a DVOM you can do a voltage drop check across the HVAC fuse (#18 in the IP fusebox) and see if you have a drop in voltage (when the AC or heat aren't working) between battery positive and the fuse or just measure the voltage at the fuse and compare it to your battery voltage. I'm surprised a former GM Tech doesn't have an answer but then again that doesn't surprise me !!
Last edited by C5 Diag; Apr 21, 2022 at 08:25 AM.
Pro
Joined: Oct 2020
Posts: 529
Likes: 197
From: Columbus, MS
It's likely an intermittent failure that only happens once briefly, and sets a code. While that code is still present in memory it keeps those systems off, but the code clears after a certain number of ignition cycles, hence why the problem seems to go away after a few days. Going into your DIC and clearing the codes may restore the systems right away; however, that doesn't fix your root issue that's causing the codes to set in the first place.
Thread Starter
3rd Gear
Joined: Jan 2021
Posts: 3
Likes: 0
From: NC
There are several different colored wires that come out of the ignition switch and feed certain circuits in the car...the HVAC module and EBCM are both fed from that particular circuit...I'd suggest looking at the ignition switch...if you know your way around a DVOM you can do a voltage drop check across the HVAC fuse (#18 in the IP fusebox) and see if you have a drop in voltage (when the AC or heat aren't working) between battery positive and the fuse or just measure the voltage at the fuse and compare it to your battery voltage. I'm surprised a former GM Tech doesn't have an answer but then again that doesn't surprise me !!
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Verdad Gallardo
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,591
Likes: 4,055
From: Cape Coral, Florida
Well if you do that testing and it does look like it is bad switch stay with an OEM…you can get one from Rock Auto…your friendly NAPA dealer may be able to get you an AC Delco.