Electrical question...
Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 5,749
Likes: 20
From: Liberty Hill Texas
Electrical question...
On Saturday, wife and I were out running some errands. Went into a store for about 10 minutes. Came back out, started car and while sitting there, wanted to turn back on the HVAC.. Pressed auto like normal and the car just just off. No lights on dash, nothing. Turned key off/ back on and lights came on dash and car started.. but turned right off again once the HVAC kicked in. Like there was zero electrics, thus no fuel, etc...
Turned off the HVAC and car started and ran just fine, no issues. Headed home.. After a few minutes driving, turned the HVAC back on and I could see the rpm's drop a for a brief second (we were at a light) but the car seemed to recover and run just fine.
What could cause this? Is this an alternator issue, a battery issue? I can purchase a battery or replace the alternator easy enough..
Any ideas on where to start to troubleshoot - or any questions?
Thanks
Turned off the HVAC and car started and ran just fine, no issues. Headed home.. After a few minutes driving, turned the HVAC back on and I could see the rpm's drop a for a brief second (we were at a light) but the car seemed to recover and run just fine.
What could cause this? Is this an alternator issue, a battery issue? I can purchase a battery or replace the alternator easy enough..
Any ideas on where to start to troubleshoot - or any questions?
Thanks
Burning Brakes
Joined: May 2007
Posts: 1,078
Likes: 5
From: Denver, North Carolina
Ok I'll bite. First things first, you must pull up the codes and tell us what you see. If you don't know how to pull them up, this is how: To list your codes, turn the ignition key to the ON position. Clear any present DIC messages (like Door Ajar, or Service Steering Column) by pressing the RESET button. Then hold the OPTIONS button down, while pressing the FUEL button 4 times. This will get you into the CODES section of the DIC.
The computer will automatically display all the codes your car is or has created. It will cycle through each code every 3 seconds. You can watch it display codes for every module in your car. If you want to write them down, go ahead. Any code that ends in H is a history code, C is current
Once the computer has finished going through all of it's automatic codes, press RESET to enter Manual Configuration. It should start with a module and show "NO CODES" or "# CODES". Press E/M to leave code mode
. write down the codes you see and report back.
The computer will automatically display all the codes your car is or has created. It will cycle through each code every 3 seconds. You can watch it display codes for every module in your car. If you want to write them down, go ahead. Any code that ends in H is a history code, C is current
Once the computer has finished going through all of it's automatic codes, press RESET to enter Manual Configuration. It should start with a module and show "NO CODES" or "# CODES". Press E/M to leave code mode
. write down the codes you see and report back.
Last edited by SebringSixSpeed; Jan 24, 2010 at 04:39 PM.
Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 5,749
Likes: 20
From: Liberty Hill Texas
Thanks, SebringSixSpeed.
There were three codes all in the B0-RFA section. All showed "history" which makes sense since they did not happen on the last start.
Here are the codes:
U1096 H - Loss of communications with IPC,
U1064 H - loss of communications with BCM,
U1016 H - Loss of communications with PCM.
There were no other codes in any of the different areas.
Thanks,
There were three codes all in the B0-RFA section. All showed "history" which makes sense since they did not happen on the last start.
Here are the codes:
U1096 H - Loss of communications with IPC,
U1064 H - loss of communications with BCM,
U1016 H - Loss of communications with PCM.
There were no other codes in any of the different areas.
Thanks,
Team Owner
Joined: May 2006
Posts: 21,473
Likes: 356
From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
Grounds need to be cleaned - also check your Battery terminals - take them off and inspect them, clean where they are corroted!
Now it is 41 pages long but at the top of this page in the "STICKY" section look at the thread on "ELECTRICAL ISSUES" find where all your grounds are and clean as stated in the post, you will be suprised how well your Vette will feel -
Thanks,matt
Now it is 41 pages long but at the top of this page in the "STICKY" section look at the thread on "ELECTRICAL ISSUES" find where all your grounds are and clean as stated in the post, you will be suprised how well your Vette will feel -
Thanks,matt
Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 5,749
Likes: 20
From: Liberty Hill Texas
Grounds need to be cleaned - also check your Battery terminals - take them off and inspect them, clean where they are corroted!
Now it is 41 pages long but at the top of this page in the "STICKY" section look at the thread on "ELECTRICAL ISSUES" find where all your grounds are and clean as stated in the post, you will be suprised how well your Vette will feel -
Thanks,matt
Now it is 41 pages long but at the top of this page in the "STICKY" section look at the thread on "ELECTRICAL ISSUES" find where all your grounds are and clean as stated in the post, you will be suprised how well your Vette will feel -
Thanks,matt
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Some great advice already. If the battery leads are tight, the other easy thing to check for a total power glitch is the wires in the rubber accordian in the door hinge area. Something caused the power loss to give those U codes. Try looking for stripped wires in the hinge area.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Also look at the solenoid connection because that's where the battery cable to fuse boxes connects. From your description its almost like the rpm at idle dropped slightly when you engaged the AC Compressor which caused the engine to die. I suggest trying to try leaving the hvac turned on and starting the engine. Then turning the hvac off and back on and see what happens. If it drops again, then I'm thinking two possibilities; either the hvac compressor is having a serious issue mechanically or the PCM's memory of the idle parameters has been lost therefore needing an idle relearn.
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Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 5,749
Likes: 20
From: Liberty Hill Texas
Also look at the solenoid connection because that's where the battery cable to fuse boxes connects. From your description its almost like the rpm at idle dropped slightly when you engaged the AC Compressor which caused the engine to die. I suggest trying to try leaving the hvac turned on and starting the engine. Then turning the hvac off and back on and see what happens. If it drops again, then I'm thinking two possibilities; either the hvac compressor is having a serious issue mechanically or the PCM's memory of the idle parameters has been lost therefore needing an idle relearn.
I'll do the test tonight - of starting the car, get it running and then off/on the HVAC and see if it does anything odd.
I drove to work this morning, car started fine and ran fine with the HVAC on when I started the car. So, if anything it's intermittent - which as we know is the best electronics issues to have!
Thanks to everyone for posting - gave me some good ideas and places to look. I'll start with the engine bay ground and the solenoid going to the fuse box and the wires in the doors.
Would it make sense to have the battery tested, just to see what it's reading? Could this also just be as simple as a battery starting to go south? It's an optima red top battery.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The engine shut off because you lost communications to the PCM and BCM.
You can loose coms for a few reasons.
- One is a compromised serial data line. The three most common places for compromised serial data wires is the left and right door wiring harnesses connectors in accordion tubes that cover the wires and the drivers seat wiring harnesses. It gets damaged thru wear and tear.
- The other is a loss of 12 VDC or ground to that module. To most modules, there are TWO 12 VDC supply voltages. One is "HOT AT ALL TIMES" and the other is "HOT in ON and START" The HOT in ON and START" supply comes from the ignition switch.
The ignition switch has been known to fail. The contacts inside get burnt and you get a low voltage or no voltage.
Bill
You can loose coms for a few reasons.
- One is a compromised serial data line. The three most common places for compromised serial data wires is the left and right door wiring harnesses connectors in accordion tubes that cover the wires and the drivers seat wiring harnesses. It gets damaged thru wear and tear.
- The other is a loss of 12 VDC or ground to that module. To most modules, there are TWO 12 VDC supply voltages. One is "HOT AT ALL TIMES" and the other is "HOT in ON and START" The HOT in ON and START" supply comes from the ignition switch.
The ignition switch has been known to fail. The contacts inside get burnt and you get a low voltage or no voltage.
Bill
