PetaVette

So this means I can't bounce off the rev limiter in every gear anymore Bummer

cbgpe

The o2 sensor wires were just fine. Removed cleaned and checked all grounds on the car. Put an oscilloscope on the alternator and found 0.2-0.6 Volts of ac "ripple" in the output. Called the dealer with the info he said that he would order and install a new alternator and a new mass air flow meter as there was a bulletin on it with one of the codes I had. BTW the problem only occurs when the car runs for more than an hour and always at highway cruise speed. The car is likely heat soaked and it may be related to a weak or marginal diode in the alternator allowing the "ripple" to increase. BTW will also change the horn fuse as some one here suggested. It cannot hurt and is a cheap date. The Vette doctors want the car back after the dealer changes the mass air meter and the alternator to see what they can do. Thanks for all the help here on the forum....CBGPE

Foosh

Yeah, that sounds right, and I learned something here too. Good work posting it here and keeping us advised.

cbgpe

Had the alternator changed out by the dealer at no charge along with the horn fuse (Do not ask me how this could help but some body here suggested it so ...) The voltage in the car is more stable not continuously fluctuating (hunting) and is staying closer to 14.2 V (13.9 -14.3 V) No indications yet of "service electrical system" on the DIC. The car seems to run better and smoother. We will see what happens with time. The dealer was very helpful despite the fact that the car had mods.
So It might be worthwhile to get an idea of how stable your voltage is. If you get the dreaded "service electrical system " warning look at your voltage if it is going up and down more quickly it could well be a bad alternator.

outnumbered

It was me. My horn fuse blew. Then I got the service message and fluctuating voltage. I have been driving on the street and the track since last late spring early summer with no additional problems.

Hope yours is resolved.

Dan

Exterminator

Thanks for posting the update - I'm glad it's all sorted out now.

extremecorvette

Your issue is an easy one to fix, replace the horns. The alternator and horn for some reason they are on the same circuit. Do you have any codes in the ECU? There is a long list of items to check but if you have the codes it will help narrow it down. I had the same issue on my dad's corvette and found it to be the horns was grounding out and running the battery down. I was able to unplug them and it went away so we just replace the horns. I have the same issue with my Z06 and I'm at the point of pulling the BCM and gauge cluster checking resistance on wires. Fun fun fun

extremecorvette

When I built a new motor 427 with APS turbo system I put all new sensors, alternator, coils, plugs, and wires on the new motor. From day one I kept getting DIC message Service Electrical System. People have told me my battery is bad but when I load test it and it was fine, and then I even went out and got a much larger battery to see if that would fix the issue, nope. The new battery is at 98% of the 675 CCA.

After that I pulled off the new alternator and had it checked out, and it was good.

I then went to an electrical auto specialist; they rechecked the alternator, battery, before starting to check out the display and all the modules on the car to find out if the issue wasn’t any of them.

I finally tracked down my issue when someone suggested swapping out my spark plugs. I used NGK BR7EF plugs and have been told by more than one tuner that they have had zero issues with those plugs. Well the issue must have been a bad plug I got in my set.

I went back to my NGK TR7IX, has anyone had this same issue and what plugs did you go with?

JPSlick

Been having this issue as of lately and out of nowhere. When I say nowhere I mean nothing has changed on the car for over a year if not more.

I've replaced the following:

-Battery
-Alternator
-Spark Plugs (Went back to stock AC Delco)
-Horn Fuse

I've inspected the following:
-All Grounds*
-Starter Wire
-Starter Ground

It's also been in 2 shops, 1 was the dealer and another an independent shop who ran through a bunch of tests and checks with no solution.

A few threads mentioned the MSD Wires and NGK Copper plugs causing issues with the C6 Corvette and service electrical system light.

Only thing left that is probable cause is MSD wires. After that the car is relatively stock on the electrical side of things.

Keep in mind the previous NGK plugs and MSD wires were on the car for 3+ years if not more.

I've read through over a dozen threads related to this problem.

Any suggestions are greatly appreciated.

JPSlick

To add, just replaced spark plug wires and the problems still persist.

Any ideas are greatly appreciated as this has been going on for 7 months and I keep dumping money blindly on parts.

I can't believe there is no way to pull the code on this to get a hint?

Its put such a damper on driving the car I'm contemplating on selling.

[Cerberus]

It is annoying, I had it come on at the tail end of last driving season and have yet to find a solution.

This car has to many low end parts to be this sensitive.

njk4o5

this message pops up on my car like once a year. I looked it up a while ago...and came up with the conclusion that nothing is wrong. It was something like when the car is at highway speed its not making much power and when the computer detects SLIGHTLY less voltage it gives you the warning.

Its a useless code. no worry. ill try to find the threads on it

JPSlick

Let me know if you come up with anything. I wish there was a way to turn off the warning permanently or use something like hp tuners to shut it off.

Car runs like a top.

I do notice it likes to do it on the highway when coasting, no load, more often.

However it does it random other times too. It's completely inconsistent except for the fact that it usually does it when the car is hot.

BLW BY

Nothing wrong?
Drive it long enough till your voltage meter is around 9.6v and tell us if anything is wrong. Try and start your car after.

I fought with this gremlin for over 2 years. Replaced all the same stuff, batteries, alternators, connectors. All the ideas of what it could be, and none of what it is.LOL.
I'll check back in 1 year and 11 months to see if the gremlin was found.
Plan A, TBD.
Plan B, replace the wiring harness.
Plan C, sell the car.

Good Luck!

Z51LS3

Same boat here.
Did you check your o2 sensors/wiring? Do you have aftermarket headers?

JPSlick

It ended up being something like an emissions gas vent solenoid code which was hidden as a service electrical light by my tuner.

They do this apparently to pass inspection.

After spending hundreds and hundreds aimlessly for over 6 months months, I contacted them to see if they can remove the light.

Soon as I got there he's like "oh yeah, we did that so you can pass inspection". He removed the code entirely from ever popping up.

I found the wire later on exposed, likely from poor installation of the exhaust when it was removed a few times by dealer.

Z51LS3

Wow, no ****. I had an exhaust installed, where is this wire?? o2 sensor wire?

Z51LS3

Did some googling on the service electrical system (there are so many forums with corvettes wow), and so many of this same common issue many left unsolved while going though same ideas!

Random FIXES that have worked for other forum members over the years;
-New alternator
-New sparkplugs
-Send ECM back to tuner (fix emissions code, or delete the DIC message).
-O2 wire burnt and fixed from long tubes (which i have)
-Horn Fuse
-fusable link
-MAF
-Battery
-Replace fuel vent solenoid


But those are a combination of the two separate messages they get. i think they are different but initially i thought were the same; (http://www.lbfun.com/warehouse/tech_info/C6/);
"SERVICE ELECTRICAL SYSTEM"
This message displays if an electrical problem has occurred within the Powertrain Control Module (PCM). Have your vehicle serviced by your GM dealer.

"SERVICE CHARGING SYSTEM"
Press the RESET button to acknowledge that you have read the message and to remove it from the display. The message will reappear every 10 minutes until this condition changes. You will hear multiple chimes when this message is displayed.
If this message comes on while you are driving, you may have a problem with the electrical charging system. It could indicate that you have a loose or broken drive belt or another electrical problem. Have it checked right away by your GM dealer. Driving while this warning message is on could drain your battery.
If you must drive a short distance with the message on, be certain to turn off your accessories, such as the radio and air conditioner.

So, mine says "Service electrical system",

i think suspects could still be;
-Check O2 wiring at long tube headers, and any loose wire from install.
-sparkplugs - will swap to AC Delco.
-Tune/pcm (contacting the tuner now).

JPSlick

By the axle back, passenger side.

Gas tank vent solenoid or something. You'll see it. No need to remove exhaust. It's tucked up right before the muffler.

Z51LS3

Ok, great thanks.