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I have noticed few days ago that when the car is idling and staying still, then sometimes there is a weird electrical failure. Seems like most electrical modules stop working and dashboard will display nonsense (only rpm and speedo gauges works correctly) with many error lights and warnings. When it occurs its random, time vary greatly from 30s to minutes, sometimes it holds good without issues. It will last until car is restarted, then everything is good again. It never happens while driving, only while idling at stop. Car is starting and running good. I have found out, that I can easily replicate that failure while the car is idling and I turn on radio. Then it always happen within few seconds. See attached video link at the bottom of this post. Fresh codes after deleting olds and after failure are below, I dont think there are any new current one which I havent had earlier. What to do ? Thank you.
PCM
P0410 HC
P0440 HC
P0443 H
TCS
U1301 H
C1287 HC
C1288 HC
BCM
B0502 HC
B0507 HC
B2482 HC
U1255 H
U1016 H
U1096 H
SDM
B0026 HC
U1301 H
IPC
U1255 H
U1016 H
U1064 H
U1040 H
U1176 H
U1088 H
U1160 H
RADIO
U1096 H
U1016 H
U1064 H
HVAC
U1064 H
U1096 H
U1160 H
U1255 H
B0367 H
B0446 H
Sounds like a possible serial data bus issue with all of those "U" codes...usually what you'll see is water temp gauge maxed out, fuel gauge reads "E" power windows don't work, all DIC messages scroll through...what we see a lot on here is a bad connection on the harness inside the drivers door rubber boot...shake that boot a few times while you are experiencing this and see if it goes away...if not and you have a DVOM we can check something at the DLC (where you hook up a scan tool to)...I'd concentrate on this and then address your other codes.
C5's get a lot of little electrical gremlins from poor connections / grounds. I would suggest (and have done this to both my C5's) - disconnect the battery, clean every ground you can get to, unplug & replug every electrical connection you can get to. In my experience this solves most gremlins.
...shake that boot a few times while you are experiencing this and see if it goes away...if not and you have a DVOM we can check something at the DLC (where you hook up a scan tool to)...I'd concentrate on this and then address your other codes.
Today the problem occured twice and surprisingly while I was driving, which never happend before. Both times it was caused by using button for washer+windshield wipers. After that I stoped and tried firmly ( but not too strongly ) shake that boot in all directions with no result. I have DVOM and I will happily await your further instructions.
Originally Posted by acroy
C5's get a lot of little electrical gremlins from poor connections / grounds. I would suggest (and have done this to both my C5's) - disconnect the battery, clean every ground you can get to, unplug & replug every electrical connection you can get to. In my experience this solves most gremlins.
Thanks, tomorrow I will inspect accessible grounds and connections.
Finally was able to view the video….if it only occurs when the radio is turned on I’d would just disconnect and remove the radio and inspect the connections and see if there is any spread terminals, fretting or corrosion visible…if everything looks OK it may be the radio itself causing this.
Finally was able to view the video….if it only occurs when the radio is turned on I’d would just disconnect and remove the radio and inspect the connections and see if there is any spread terminals, fretting or corrosion visible…if everything looks OK it may be the radio itself causing this.
Yes, I thought radio might be responsible for this. But as I said earlier, it also occured when I used washer+wipers and radio was off... so idk. I still have to check those grounds tho.
Yes, I thought radio might be responsible for this. But as I said earlier, it also occured when I used washer+wipers and radio was off... so idk. I still have to check those grounds tho.
The ground for the wiper is G201 and part of splice pack SP201...I would remove the "comb" from the splice pack and inspect it...if still occurring we can go from there.
So I checked G201 + that splice pack + easily accesible grounds in engine bay + BCM and connectors to it. Everything seems good, yet I rather recleaned them all. After this I was not able to recreate that failure with using wipers, but failure after turning on radio still remains. However if I turn on just electricity and radio, without starting engine, then radio remains playing and everything else seems to work good too. Just combo engine on + radio on looks like to cause failure almost always. Also I think one time it occured while I was just driving, without using or turning on anything, but I am not 100% sure. So should I still dig up and check radio connectors, or look somewhere else first ?
Probably what’s happening is power or ground from the radio is back feeding onto the serial data line causing the issues…there are 2 splice packs where you were checking and SP203 is the ground for the radio…did you remove the buss bar or “comb” off the splice pack ??…it is shown in that video so you know what it looks like when removed…when the condition happens get your voltmeter and see if you have either 12 volts or ground on pin 2 on the DLC with key on…if everything is good you will see the voltage fluctuate around .2 to .3 volts…as in the video it is a 0-7 volt square wave but you will not see 7 volts…if we see 12 volts or ground on pin 2 we will have to remove both splice packs as in the video near the BCM and check each pin for a short to power or ground.
Probably what’s happening is power or ground from the radio is back feeding onto the serial data line causing the issues…there are 2 splice packs where you were checking and SP203 is the ground for the radio…did you remove the buss bar or “comb” off the splice pack ??…it is shown in that video so you know what it looks like when removed…when the condition happens get your voltmeter and see if you have either 12 volts or ground on pin 2 on the DLC with key on…if everything is good you will see the voltage fluctuate around .2 to .3 volts…as in the video it is a 0-7 volt square wave but you will not see 7 volts…if we see 12 volts or ground on pin 2 we will have to remove both splice packs as in the video near the BCM and check each pin for a short to power or ground.
I am not really proficient with electricity but I tried. Here are the results. I started the car then forced the failure via turning on radio, then I went to check voltage on DLC on pin 2. My reading on pin 2 was 9.9-10 volts (on pin 16 it was 14,5, same as battery). Then I turned the car off and went to remove combs from those 2 splice packs near bcm. They all looked good and clean. So I restarted the car again and I started with bottom pack, the one with 4 wires. Im not sure on which side is first or last pin, but here are my readings on them:
First one - 0
2 - blank
3 - 14,5
4 - 14,5
10 - 0,9
rest was blank too
Pin 16 should be hot or voltage “at all times” so that is not a problem…with the car running seeing 10 volts at pin 2 IS a problem…now all these readings of around 14 volts on each wire is with the combs REMOVED ??…if you remove the comb from the splice pack with the 8 or 9 wires the car will NOT start and run…you said you restarted the car so I think you made these voltage measurements with the comb installed…by removing the comb you isolate each module off the serial data bus and so we check each wire for voltage…you should see 10 volts on one of those wires…did you watch the video ??…did you see how he checked each wire and found 12 volts on one of the wires…you should check the voltage with key on…if you want to start the car you will have to make a jumper wire between the light and dark green wires (see picture) these are for the PCM and BCM…if you jumper them the car will start with the combs removed !!
Yes, it was with combs removed. Car started and was running, beside same errors like when I forced that failure via radio before. I watched the video. I did not jumper those wires and did not found anything unusual there. After reading 10 at DLC I shut car off, then I just removed combs from those packs and started car again. Then I went to read packs and this was the result. I even drove car back to my parking place with combs removed after I was done... I can make video of it...
A long time ago I demonstrated to someone how I can reproduce what you are seeing by jumping 12 volts from pin 16 to pin 2…car would not start and all those DIC messages…doing this did no damage to any module…I pulled both combs and jumped pins for BCM and PCM and car started…I have NO idea why your car is starting and running with BOTH combs removed…that shouldn’t happen !!…don’t know what else to tell you !!…YES, make me a video of the car starting and running showing splice packs removed....very suspicious !!...do you have a scan tool ???
I really appreciate all your help. I understand how it is supposed to work, but sometimes I feel like this car has its own life . Here is the video, I drove it just a little bit, but it can definitely do more even in this state.
I have NO idea why it’s starting and running ??????...even running and with modules isolated you still have the DIC messages and I see fuel gauge on E and water temp maxed out....all of your modules are isolated and I don't see why you are reading voltage on ALL the wires.
Like in the video can you do the "Class 2 DTC check" with key on and combs installed ??...can you communicate with any modules ??...if 12 volts is on pin 2 you will not be able to communicate with any module....WEIRD !!…maybe one of our electrical engineer members can chime in who is more knowledgeable than me !!!
When the failure was present then the Tech2 could not communicate with any modules, just forever waiting for data. While car was ok then Tech showed 10 modules and all had YES under Present column.
Also I tried to reread packs with combs off with different DVOM and I got totally different results. Or me or my friend did something totally wrong yesterday or today... I dont know anymore what is going on, please have patience with me . Todays results are:
On DLC pin 2 with combs attached again I got only 0.9-1,2. Pin 16 was as yesterday.
Lower pack with 4 wires and combs removed: 0 on all expect last black with white stripe wire, It was jumping fast up to 1,8
On upper pack with more wires and combs removed: 0 on purple, then all of them had arround 0.02-0.3 With one expection if I remember it correctly, light blue having up to 1,5. ( it also looked like the wires closer to this one had more, those outside had less the more they were from the high one)
Also I tried to test various BCM and other things available in Tech2. Like automatic tests, turning things on/off or increasing/decreasing them. Nothing caused any problems. Just the radio is always 100% way to crash it... but also after one start the failure occured in few seconds without doing anything...
Status update: Because the problem always occured after turning on radio, I pulled fuses for radio and speaker. Sadly after letting the car idle for a while, same failure appeared again. Any help is welcome.
Random electrical failure while idling
. Here is the video, I drove it just a little bit, but it can definitely do more even in this state.
. Todays results are: