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Fun with the C5 electrical system, FIXED!!


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UPDATE[/d]

With out going into boring detail, I found the cause of my electrical failure.

-dramatic pause-

It was the Passenger side Door module.

Some how that unit failing caused a Communication failure with many other systems. Im guessing a short occured and the other systems went into "safe" mode to protect them selves.

ok im glad i found it. off to buy a new/used one.

...orignal post...

Ok this one is bizarre, and if you have any feedback that would be neet.

Ok Here are the Symptoms

With a fresh clearing of all DIC codes, and after 3 min of 5 mph driving. I get this lists of codes:

10 PCM

P1626 Theft Deterrent System Fuel enable Circuit -C

28 TCS

U1016 Loss of Communications with PCM

U1301 Class 2 Circuit Shorted to battery Refer to Data Link Connector System Check in Wiring System

40 BCM

U1255 Generic Loss Communications

U1096 Loss of Communications with IPC (No State of Health Message)

U1016 Loss of Communications with PCM

58 SDM

U1301 Class 2 Circuit Shorted to battery Refer to Data Link Connector System

Check wiring in system.

60 1PC

U1255 Serial Data Line malfunction

U1016 Loss of Communications with PCM

U1064 Loss of Communications with DCM

U1040 Loss of Communication with TCS

U1176 Loss of Communications with RFA

U1088

99 HVAC

U1064 Loss of Communications with DCM

U1096 Loss of Communications with IPC (No State of Health Message)

U1160 Loss of Communications with LDCM

U1255 Serial Data Line malfunction

A0 LDCM

U1064 Lose of Communications with DCM

A1 RDCM

No Comm

A6 SCM

U1300 Class 2 Circuit Shorted to ground Refer to Data Link Connector System Check in Wiring System

U1255 Generic Loss Communications

B0 RFA

U1255 Generic Loss Communications

U1096 Loss of Communications with IPC (No State of Health Message)

U1064 Loss of Communications with DCM

U1016 Loss of Communications with PCM

Fuel gauge goes to Zero

Oil pressure goes to Zero

Engine Temp goes to zero

Roxxane’s DIC says

SERVICE ENGINE SOON

REDUCED ENGINE POWER

LOW FUEL

LOW TIRE PRESSUE

SERVICE TRACTION SYSTEM

And

SELL ME AND GO BUY A C6

While digging into the car discovered a small amount of dried battery acid (optima red top.7 months old) smattered and pooled. OK I have seen this before.

The battery is at 12 V (car off). The DIC shows 14.4 v to 14.v (car running). The alternator fails and is always charging the battery. The Optima’s don’t like this because they are GEL Filled and release gas very slowly. The gas builds up like a balloon and the plastic battery pops a leak. It looks like some one took hard tap water from a squirt bottle and gave it a couple of shots in the battery area.

It is possible that my stereo and Euro 110watt headlights over tax the regulator and caused it to fail? Probably.

I will be replacing the Battery and the alternator.

So I followed the trail of the leaking battery acid and found NO WIRE damage. There was some acid corrosion from the previous owner. I knew about this and had given it a through bath in Baking soda and water (this was 7 months ago). The split loom has some small damage to it from battery acid (about half the size of a dime). It was more brittle than anything else. TO be sure I split it open and exposed the PCM wiring harness.

The wires are as clean as a whistle. NO damage whatsoever.

This is where I need help.

Question A: Can a low battery volts/amps cause this string if DIC errors?

Question B: Looking at the error codes; they are mostly “Loss of Communications” stuff.

In the Wiring Layout of the car is there one place where all the wiring for these failing modules come together? So I can look for damage.

Thanks for any help.

Cheers

Chad

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It sounds an awful lot like battery problems. Easy way to check is just do a quick swap and see...if you have another car/truck to do a quickie swap.

If not, maybe someone lives close and can swing by and do a quick battery swap.

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The most common electrical problem and what might cause this list of various problems is grounds. Before I went out and bought a new battery and alternator I'd check all the chassis grounds. I wish I could tell you more about their locations, etc but if you check CF I know there have been threads about such problems. I believe one is on the drivers side frame rail under the hood. Good Luck!

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The most common electrical problem and what might cause this list of various problems is grounds. Before I went out and bought a new battery and alternator I'd check all the chassis grounds. I wish I could tell you more about their locations, etc but if you check CF I know there have been threads about such problems. I believe one is on the drivers side frame rail under the hood. Good Luck!

and another on the passenger frame rail exactly opposite the drivers side.

also, mark showed me there are several under the kick panel on the drivers side

other than that, i'd have to dig out the thread on CF to tell you more.

***EDIT***

the thread with all the ground points is here

http://forums.corvetteforum.com/showthread.php?t=896875

the picture that tells you where all the ground contact points are is this one

C5ZO6pictures012.jpg

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Guest UVETTYA

Most of the problems are a bad battery, and if yours is over 2 yrs old you've gotten your use out of it. Arizona heat kills batteries.

PM me if you want me to come by tomorrow and swap batteries to see if that's the problem. I have an Optima red top

Steve

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Well all those codes do not sound good. I would first start with your battery. The Optima's have had a rush of bad ones lately.

If it is damage to your wiring harness, that is not good. I had it replaced on my old 99 because of Battery Acid damage. I could not get it covered under extended warranty because I was just out of factory. They each said that the other should cover it. Go figure I got no where with them.

I then contacted my Home insurance and they covered it after they inspected the damage caused by the bad battery. They made it a point to inspect the vehicle and battery.

The process to replace the wiring harness was around $5K. I only had to pay my home owners deductible.

Good luck trying to figure whats wrong, and hope it is not expensive fix.

Phil... :devil

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Most of the problems are a bad battery, and if yours is over 2 yrs old you've gotten your use out of it. Arizona heat kills batteries.

PM me if you want me to come by tomorrow and swap batteries to see if that's the problem. I have an Optima red top

Steve

i have to disagree with your statement above - while arizona heat DOES kill batteries, Optima, in my opinion is the best battery on the planet - why you ask? well, i'm glad you did, i had a red top in my truck (high wattage car stereo, and several high wattage amplifiers - to the point my headlights would dim!) i had the SAME battery in that truck for almost 8 years - yes OVER 7 YEARS! i also had the battery run dead SEVERAL times like a dumbass leaving my headlights on at work during those dark morning drives - the optima was so awesome that after receiving a jump start to get the car started, the alternator had the battery fully charged and it would start up under it's own power after my 1 hour drive home! try getting that kind of life/performance out of ANY lead acid battery! :bs

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Guest UVETTYA

You were lucky.

I agree that the Optima is a great battery, but I don't expect to get more than two years out of any battery in Arizona. If you get more than that, you're lucky. :yesnod

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You were lucky.

I agree that the Optima is a great battery, but I don't expect to get more than two years out of any battery in Arizona. If you get more than that, you're lucky. :yesnod

:agree I traded the C5 cause the Red Top was just over 2 yrs old. I figured it was going to go any day so why put up with the hassle, just get a new Vette. :D j/k

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You were lucky.

I agree that the Optima is a great battery, but I don't expect to get more than two years out of any battery in Arizona. If you get more than that, you're lucky. :yesnod

:agree I traded the C5 cause the Red Top was just over 2 yrs old. I figured it was going to go any day so why put up with the hassle, just get a new Vette. :D j/k

I traded cause I was out of gas. :thumbs They filled the tank up in the new one.

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Thank you for the advice,

While the battery is only 7 months old, it did rupture and spring a leak (ever so slightly).

I will replace it.

Swapping out the battery may not solve my problem. There is a Small amount of corrosion on the Positive terminal wire. Experience has told me that a small amount of corrosion (from age, battery acid, and PFM [Pure Fu$%ing Magic]) inside the copper windings of a main lead like this can act like a resistor and reduce the Amperage that travels across the wire. Normally you look for swelling of the wire jacket, but even a small amount can do a number on you.

Less Amperage= Less Volts. Less volts makes the Alternator work harder and possibly damage the regulator (and PCM? …shudder…)

Depending on the price I just may upgrade the Alternator to be 100% sure that its not causing an issue.

The only thing that is bothering me is that all of this came on quickly, and it is consistent (not random, or intermittent). My gut is telling me to look for something obvious, but I haven’t found it yet.

Thanks for the link Chris. That will get me started.

Chad

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Guest Steve Mulvey
Well all those codes do not sound good. I would first start with your battery. The Optima's have had a rush of bad ones lately.

If it is damage to your wiring harness, that is not good. I had it replaced on my old 99 because of Battery Acid damage. I could not get it covered under extended warranty because I was just out of factory. They each said that the other should cover it. Go figure I got no where with them.

I then contacted my Home insurance and they covered it after they inspected the damage caused by the bad battery. They made it a point to inspect the vehicle and battery.

The process to replace the wiring harness was around $5K. I only had to pay my home owners deductible.

Good luck trying to figure whats wrong, and hope it is not expensive fix.

Phil... :devil

Rewiring is not that big of a job, just look what a breeze it is on my car which has about a quarter of the gizmos you have... group of 15 indeed....

Gee, your car can join mine...

Take Eddie's advice, get another car...

Try the connector to your computer too, all comm has to go through there...

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Guest AZ Power & Sound
Thank you for the advice,

While the battery is only 7 months old, it did rupture and spring a leak (ever so slightly).

I will replace it.

Swapping out the battery may not solve my problem. There is a Small amount of corrosion on the Positive terminal wire. Experience has told me that a small amount of corrosion (from age, battery acid, and PFM [Pure Fu$%ing Magic]) inside the copper windings of a main lead like this can act like a resistor and reduce the Amperage that travels across the wire. Normally you look for swelling of the wire jacket, but even a small amount can do a number on you.

Less Amperage= Less Volts. Less volts makes the Alternator work harder and possibly damage the regulator (and PCM? …shudder…)

Depending on the price I just may upgrade the Alternator to be 100% sure that its not causing an issue.

The only thing that is bothering me is that all of this came on quickly, and it is consistent (not random, or intermittent). My gut is telling me to look for something obvious, but I haven’t found it yet.

Thanks for the link Chris. That will get me started.

Chad

The bad news about the leak is your PCM is directly under the battery... the issue Phil was talking about is EXTREMELY common in C5s and from the symptoms youre explaining it sounds like you might be a candidate! Get a sealed battery such as an Optima in there ASAP and see if that helps... if not, pull the battery out, then the battery tray and inspect the PCM for corrosion on the harness etc.

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  • 2 weeks later...
You can't just tell us she's fixed without telling us how!!!! :toetap:lol

At the moment she is fixed because I have the door panel off and the passenger door module removed from the system.

My passenger window and door lock will not work. That is much better than have the entire car switch into limp home mode and become crippled.

I trouble shoot complex computer systems all day long. I tackled this in the same manner.

- What are the symptoms

- Can the symptoms be duplicated

-What is the commonalty in the systems.

OK research told me that battery acid and the PCM do not play nice together.

So I examine the battery and this is what I found.

battery.jpg

I have seen this before. The battery gets over charged, gas builds up, it swells and springs a leak. A very fine but high pressure leak. It will spray everywhere.

So I have to tear down and follow the battery acid trail.

Yep there is a pool building in the battery tray.

batterytray.jpg

And when I got to the PCM this what I saw

pcm.jpg

Now how horrible as that looks, it’s not that bad. 99% of that damage is old.

When I first got the car this is one of the first places I looked.

Upon seeing this I (the first time) I quickly removed what I could and scrubbed all surfaces with hot water and baking soda to neutralize any acid.

The collection of white stuff is the after effect of battery acid. I did not remove the battery tray the first time I saw this so it was hidden from me.

The car ran fine for 8 months.

The only new acid that I could see is the tiny speck of blue green acid on the lower right of the picture.

Underneath the PCM was this

pcmcable.jpg

pcmcable2.jpg

That is ugly but not dangerous per say. That is mostly water and rust. No battery acid here.

So at this point in time there is no definitive reason for what is causing my havoc. I remove the PCM and surrounding stuff to dig deeper.

As always I clean the parts as I remove it.

I go up top to look there and this is what I find.

batteryconnector.jpg

The picture is a bit fuzzy, but look where the red cable is making contact with the ring terminal. The blue green stuff is a collection of battery acid. It does not conduct electricity and acts like a restrictor plate on a NASCAR engine.

The amount you see here is not bad.

But I haven’t found a definitive culprit yet. So I repair and replace this part, the battery and a small ground located near by (thx to Chris’s picture from above).

I perform the work, get the car back on the ground, start her up and it still goes AWWOOGA AWOOGA WHOOP WHOOP SERVICE ENGINE SOON, REDUCED ENGINE POWER, SELL ME AND GO BUY A C6 NOW.

I yell FUDGE ME very loudly.

So the battery cable was not it. Where do I go now?

Then I remember

- What are the symptoms?

- Can the symptoms be duplicated?

One of the symptoms is the power window and door lock will not work. So I forget the Haywire system and focus on the power window.

At first the window would operate when the door was open, but not closed. Odd?

Ok so the motor is good, communication is good. It doesn’t take a rocket scientist to determine that the Door Module is bad.

So I pull the Module and start the car.

Purrs like a Kitten. No alarms No sirens.

My theory is that this unit failed and caused a short on the communication bus that all the other systems share. This Communication Bus is the "main Highway" all the moduels use to talk to each other.

GM parts on line has a new module for 216.00 + plus shipping. sigh.

cheers

chad

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Damn Chad, looks like you had the BIG shovel (dig deep) out for this one!!! :bang Strange??? At least now you have a acid free and clean battery/PCM area! Juat a little piece of mind! :clap

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You are the MAN! :bang Well done. You do know your shi'ite. We only bust your balls 'cause of your spelling, I swear. "We kid because we love" - Dr. Phil

And if you're selling that heap for a C6, I wanna pilfer through your C5 go fast goodies! :devil

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