KeatsArizona

9/15/23
2004 C5 convertible base model.
I bought this car in April 2017 with 50K miles on it. It has 52K on it now. Runs like new when it's running.

I've installed two new batteries since Ive owned it. The heat here in Phoenix just eats them alive in all of my cars.
The current battery is about 1 year old. For some reason it keeps draining and I have to put the charger on it to bring it back up.
I last charged it overnight on Sunday/ Monday and when I tried to start the car just now, it did click but would not turn over.

Now for the interesting question:
Its had two previous owners and when I bought it, I received all of the paperwork for repairs, modifications, etc that were done by the former owners. Full note book and receipts. However there was nothing about the wires as described below.

I opened the Fuse Relay Center next to the battery and there are three non factory wires (small gauge) attached to three fuses (#'s 8, 9,10) and they correspond to the Headlight Lo Beam right side, Headlight Hi Beam right side, and Headlight Lo Beam left side.

Apparently the wires are to obtain power when the headlights are turned on, but not otherwise. These wires lead to a relay (Note , #'s 8 and 10 are joined together outside of the fuse box ) and lead to a single blade on the relay which should provide the voltage from both 10 amp fuses together (does that make it 20 Amps? ). The relay then has a single small gauge black wire leading to a ground on the body firewall.

A heavier gauge wire (Red) runs from another relay blade to an in- line H.D. fuse (Yellow) and from there it goes to a common hot post mounted on the inner fender with two other heavy wires also attached. From there I have no idea where those wires lead.

I do have an aftermarket radio installed by a previous owner and there were LED lights in the trunk that had a tendency to remain lit when the car was parked. I disconnected the trunk lights last year so there should be no current draw.

Maybe after I get the battery charged up again, I'll be able to check the radio and the front parking camera installed in the under bumper splash pan. It's not factory either but it sure does come in handy when approaching a parking block.
There is a toggle switch in the center console that can retract the antenna when desired but I'm not sure if that's factory or a previous owner installed switch. ?
There are no other aftermarket items on the car. I can't imagine what could be the cause of the battery drain other than these wires.

So I'm just stumped. Any thoughts will be welcomed. I've disconnected the jumper wires for now and maybe that will stop the drain.

Thanks,
Keats
Peoria, Az

I'll try to take a photo or two and post it.

C5 Diag

C5 Diag

billschroeder5842

Well, it seems to me that you have identified your problem area. Since you have no idea what the wires do or what they ae connected to, why not just remove them? Since this is an aftermarket modification it is a good bet that this is the source of your drain.

Trog

The relay/wires are most likely the mod to have low beams stay on with the high beams... Have it on my car for years w/ out issue. Also installed for a number of friends... It really helps with night time lighting when you can use the hight beams. Most likely you need to follow the procedures to find your current draw.

KeatsArizona

Very interesting. I was not aware of a modification like this.
Considering all the paperwork that I got with the car, I'd think that something like this would have been addressed in the notebook.
I'm going to leave the wires running to the fuse box next to the battery unattached and try the lights etc. Hopefully this is the cause.
I have to mention that when I first got the car, I did not have this problem. I have not added or subtracted any of the aftermarket items since I bought it so I can't understand why it's getting worse now. Very strange.
Battery should be fully charged by now so it's time to start checking on things.
Thanks for the reply.
Keats
Peoria, Az

KeatsArizona

Saturday P.M.
Update:
The battery is fully charged and the car started right up. The post that the repay was attached to is a battery post that is a factory item. Whomever added this relay to the car unscrewed the battery post nut (1/2") and attached a pigtail to it and re-secured it with the nut.
I then checked the various parts of the car. I turned on the headlights and they both flipped up immediately. The low beams were illuminated.
I pulled back on the directional lever and the hi beams illuminated as well as the lo beams. That was all four lamps lit at the same time.
I pushed on the directional lever and the hi beams illuminated with out the lo beams. So just two lamps were illuminated.
I turned on the radio and it played. I checked the power antenna and it was raised. I pushed on the button in the center consul and the antenna was lowered. I pushed it again and the antenna raised again.
I have no warning lights showing and the heads up display is working. The heater/ A.C. blower is working and is adjustable like it should be. The windows both raise and lower.
At this point I can't see any thing that's not working.
So I disconnected the relay from the "Battery Common Post" and tightened up the factory wiring there minus the add on relay.
I went thru everything again and everything worked just like when the relay was attached. So it made no difference to the car whether or not the relay was attached. I have no idea why there was a separate relay added to this car.
Is it possible that the car's "LoJack" is part of the relay circuit? It was on the car when I bought it but I never activated it. I'll try to start the car over the next few days. The voltage using a voltmeter at the battery terminals was about 13 volts when I disconnected the charger and with the engine and key off. Hopefully it will stay charged now.
I tried to post a few photos but I can't get the snap shots to reduce enough to up load them .

KeatsArizona

KeatsArizona

9/18/23
Latest update.
Everyday you live and learn.
So I had the battery fully charged on Saturday and when I tried to start the car this morning, it barely turned over. Eventually it caught and ran kind of ragged.
I got a message on the display near the speedometer and it read "Service Column Lock". That's the first time I've ever seen this message.
I read the owner's manual and it said that this message was only displayed on C5's with manual transmissions. I have an automatic trans. Hmmm?
I did more research and found some postings here for that message. Apparently it only applied to Vetts with Auto transmissions going overseas. That's not the case with my car.

I looked up the LMC5 override module that eliminates this problem and then I contacted the company in Calif. I was asked to call Richard there and we spoke for a while and he explained that because I could turn the steering wheel in both directions with the engine off and the key out, I had a Vette made without the steering wheel lock as approved by the DOT some years back. There were a lot of problems with the locking assy and the DOT gave the company permission to eliminate the lock. Good to know huh ?
I was assured by Richard that there was nothing in the steering column that would drain the battery so I'm still trying to determine what's draining it overnight.

Now for the Relay that I posted photos on in my previous messages. I was able to find this relay assy as a part that could be added to the fuse panel to allow the headlights to illuminate both Hi and Lo beams when the Hi beams were activated. Removing it has no effect of the battery drain. I may reinstall it again.

So I'm at the point of doing a battery drain check fuse by fuse. Not a lot of fun but I believe it's my last resort. Sure wish there was a way for an OBD2 to plug in and detect a battery drain. Sure would be nice.

All for now,
Keats
Peoria, Az

ncali

when I had a battery drain problem one of the switches for the Drivers seat remained in the on position . broken in that position. I changed the switches out and cured the problem

There is a sticky thread on battery drain

mmartinez

There is a way to isolate the fuse box's and find out which fuse box has the current drain. You lift the power cable running from the engine fuse box to the interior fuse box, its also good to have a DVM configured as an ammeter in series witn the negative battery cable and terminal, acceptable current drain should be around 25ma, meter should be set on 10A scale, and you should wait 20 minutes.

C5 Diag

A faulty alternator diode can also cause a battery drain...disconnect the red B+ wire at the alternator and see if the drain goes away.

KeatsArizona

I just replaced the alternator in August. The OEM went bad so I put in a new one.
Battery drain was present prior to Alternator problem.