Loss of Comm Codes Back Again
Thread Starter
Race Director
Joined: May 2012
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From: Phoenix area, AZ
Loss of Comm Codes Back Again
After clearing my previous U1016, U1064, and U1096 codes out to see if they would reappear, all three of the codes were back yesterday. Either on the way to, or back from, picking up a set of chrome exhaust tips from another forum member something hit my passenger side DRL and cracked the housing. I pulled up my codes after I saw the crack to check the status of the lights and had a 2578 indicating a bulb had burned out, but I also had all three of the previous codes back.
So it's obvious that I have a problem, but after reading thread after thread I haven't found anything that points to where I should start my search for the cause of these codes. It also appears that the cause is different for everyone who have these pop up.
Is there a logical starting point and progression for searching for the root cause? Electrical is not my forte; give me something mechanical and I'll jump in with both feet, but when it comes to wiring I'm out of my element. I don't have an ohm meter or any other kind of electrical testing equipment.
So it's obvious that I have a problem, but after reading thread after thread I haven't found anything that points to where I should start my search for the cause of these codes. It also appears that the cause is different for everyone who have these pop up.
Is there a logical starting point and progression for searching for the root cause? Electrical is not my forte; give me something mechanical and I'll jump in with both feet, but when it comes to wiring I'm out of my element. I don't have an ohm meter or any other kind of electrical testing equipment.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Do you have a loss of comms message for specific modules or just the U1016, U1064, and U1096 DTCs??
When you pull the DTCs what modles say NO COMMS?
What year car and what MODS?
BC
When you pull the DTCs what modles say NO COMMS?
What year car and what MODS?
BC
Thread Starter
Race Director
Joined: May 2012
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From: Phoenix area, AZ
Sorry about that. The only "no comm" message I get is for the radio (80). The car is a 2000 base coupe and the only mods done to the car so far are an aftermarket stereo system that replaced the Bose head unit and speakers, and a throttle body bypass. Other than that I've only changed the plugs & wires, installed a new surge tank, and replaced the valve cover gaskets and grommets. I've cleared these codes out several times over the past few weeks but they keep reappearing. Nothing has been done to the car since the the last time I cleared the codes.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Sorry about that. The only "no comm" message I get is for the radio (80). The car is a 2000 base coupe and the only mods done to the car so far are an aftermarket stereo system that replaced the Bose head unit and speakers, and a throttle body bypass. Other than that I've only changed the plugs & wires, installed a new surge tank, and replaced the valve cover gaskets and grommets. I've cleared these codes out several times over the past few weeks but they keep reappearing. Nothing has been done to the car since the the last time I cleared the codes.
The U series DTCs can be caused by several things.
How old is your battery and is it fully charged? Have it tested to see if it has the required cold cranking capacity and reserve capacity.
Your ignition switch can also be dirty and not output the correct voltages all the time.
Check the battery by having it tested and if it is good, maybe clean the ignition switch contacts. U series DTCs can be caused by low voltage.
BC
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From: Phoenix area, AZ
I had the battery tested a few weeks ago and it showed to be in good shape; not sure how old it is but it looks fairly new. I've only had the car since the end of January so I have no way of knowing an actual age. The ignition switch could be a real possibility. I had a problem last week with the car going into security mode after trying to start it. I think the code it put up was a B2721. I switched keys to a newer key thinking my key might have been worn and it started up with no problems since then. Is the switch you're referring to the one with the white plastic-cased housing that I've seen a few pics of here? Where exactly is it located? I have a new instrument panel bezel coming tomorrow so I'll have everything disassembled waiting for delivery.
Tech Contributor
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Are you talking about the instrument panel fuse box and the BCM.\??? Under the toe board in the passengers foot well behind the carpet. The fire wall cover is a panel.
Thread Starter
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Thread Starter
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From: Phoenix area, AZ
I just got done reading through the repair instructions. I don't understand half of it, and don't have the testing equipment it calls for, not that I know how to use those either....
Thread Starter
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Here are 3 links to Bill Curlee posts concerning the ignition switch (different than the ignition cylinder):
diagnosis
http://forums.corvetteforum.com/1568186703-post64.html
removal
http://forums.corvetteforum.com/1571067145-post107.html
repair procedure
http://forums.corvetteforum.com/c5-t...ch-repair.html
diagnosis
http://forums.corvetteforum.com/1568186703-post64.html
removal
http://forums.corvetteforum.com/1571067145-post107.html
repair procedure
http://forums.corvetteforum.com/c5-t...ch-repair.html
I do have one question. I tested the battery voltage since I was right there with the DMM and it shows 12.11. Is that sufficient or should I be looking for a new battery?
Last edited by Corvette_Ed; Aug 1, 2012 at 12:15 PM.
107 degrees!
Thats friggen DUBAI UAE hell hot!
I bet you will cherish FALL!
Burning Brakes
Joined: Mar 2012
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From: Cherry Hill NJ
12.1 is low, should hold over 12.6. Try putting it on a trickle charger overnight, then drive it and see what it's holding. I get these 3 codes on my '00 FRC track car all the time, I just keep clearing them, and no ill effects so far. I just replaced my battery Sunday, took it out on track Monday, and still got the codes. I always disconnect my battery via a quick disconnect, I'm wondering if that causes an issue.
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Good to hear about the battery; that's one less thing I need to worry about.
Last edited by Corvette_Ed; Aug 1, 2012 at 02:53 PM.
Thread Starter
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From: Phoenix area, AZ
You might want to take a look at your ignition switch. I just pulled the green casing off of mine and several of my contacts are black, which indicates bad contacts. These are most likely the reason why my codes keep coming back after clearing them. Yours might be the same.
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From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
Thread Starter
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From: Phoenix area, AZ
Ouch, that's not good. Since I really have no idea how old the battery is, I suppose the smart thing to do at this point would be to just go ahead and replace it. I'm glad I thought to test it, and thanks for the info. Once I get everything back together I'll pick up a new battery.
Tech Contributor
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From: Dyer, IN
You might want to take a look at your ignition switch. I just pulled the green casing off of mine and several of my contacts are black, which indicates bad contacts. These are most likely the reason why my codes keep coming back after clearing them. Yours might be the same.
Thread Starter
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Ah, got it. It didn't sink in the first time around. Heat must be getting to me.
And speaking of heat, I've got the ignition switch cleaned up and put back together. It's time to go out and start putting things back the way they're supposed to be. Hopefully my new glove box will be here soon too so I can have everything fixed on the inside. I even got the LMC5 installed and tested earlier so with the ignition switch all of my electrical work should be complete.
Tomorrow is the brake job.
And speaking of heat, I've got the ignition switch cleaned up and put back together. It's time to go out and start putting things back the way they're supposed to be. Hopefully my new glove box will be here soon too so I can have everything fixed on the inside. I even got the LMC5 installed and tested earlier so with the ignition switch all of my electrical work should be complete.
Tomorrow is the brake job.
Last edited by Corvette_Ed; Aug 1, 2012 at 04:00 PM.
Burnout
Joined: Jan 2004
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From: South Surrey (White Rock) British Columbia
Codes
Sorry about that. The only "no comm" message I get is for the radio (80). The car is a 2000 base coupe and the only mods done to the car so far are an aftermarket stereo system that replaced the Bose head unit and speakers, and a throttle body bypass. Other than that I've only changed the plugs & wires, installed a new surge tank, and replaced the valve cover gaskets and grommets. I've cleared these codes out several times over the past few weeks but they keep reappearing. Nothing has been done to the car since the the last time I cleared the codes.
mrgil
