I killed buttery by leaving lights on. I jump start the car to get home where I charged the battery overnight. I fired engine up and drove to work. Upon leaving the office buttery was dead. I thought that when I drained the battery plate or plates cracked so I bought a new buttery. But that didn't fix the problem. After disconcerting one of the battery posts I noticed that when I touched the post with the disconnected wire I could hear a click and that significant current was drawn because I got welding-like effect - bolt on the cable was sticking to the port. I found out the the sound was coming form the rh headlight motor. When I put my hand on it I could feel the click. So I unplugged the headlight. I couldn't feel the motor kicking anymore but i could hear the clicking sound coming from under the headlight. Please advise.

 

The headlight control module is very near the right side headlight. That may be the source of the noise and problem. It is powered by fuses 3 (right)and 4 (left) in the engine fuse box. Suggest you pull those fuses and see what happens. You should still have a spark when you connect the battery but nothing like you described unless there is more that one significant drain.

If you need to do more battery drain diagnostics here is some guidance:

Here is some info for determining if you have a parasitic drain. Let me know if I need to clarify anything of if I can help in any way.

Suggest you remove the hood light bulb first so it does not provide a drain.

For measuring battery drain I would hook up an ammeter to the negative side of the battery by removing the negative cable and measure between the cable and the negative battery post.

When you connect the ammeter the car should draw several amps until it goes into "sleep" mode which can take several minutes. Normal sleep mode drain should be between 17-22 milliamps. You will need an ammeter that can transition from whatever the drain is down into the sleep mode. If you have a drain I suggest the following:

Once you determine you have a drain with an ammeter what I recommend first is to listen to each fuse box and see if you hear any relays operating. If not, then place your hand on each relay to see if any of them feel hot. That can be the start if you find something like that is happening.

If nothing shows up you can hear or feel then I recommend you separate the two fuse boxes from each other. This is easy and done by removing the Red cable from the engine fuse box that feeds the passenger fuse box. It is on the right rear side of the engine fuse box. There is a stud there where the large Red wire from the battery connects. Just remove the nut and disconnect the large Red wire feeding the passenger fuse box and reattach the Red battery cable. NOTE: I would recommend disconnecting the negative ammeter hookup when working on the positive side doing this.

What you will be doing is measuring the drain with an ammeter to see if disconnecting the passenger fuse box causes the drain to go away or not. By depowering the passenger fuse box you will depower the BCM which controls the sleep mode so do not expect the sleep mode to happen.

If removing the feed to the passenger fuse box you then see you have eliminated the drain then you know it is something related to those circuits. If it does not reduce the drain then you know it is related to the engine fuse box. It could be a rare case where you have some drain via both fuse boxes and we can deal with that if you think it is the case.

Once you basically know where it is then you can remove fuses and relays to see where the drain is coming from.

 

Looks like we finally got Spring in MI so I was able to get to my Corvette. As you recommended I removed fuses 3 and 4. It hasn't stop the clicking. I removed every fuse one by one. Clicking never stopped. I put my hand on the headlight motor and I'm sure it's the one that clicks when I connect cable to the battery port. Click stops when I unplug the headlight connectors. But even though clicking is gone there is significant amperage drawn. I turned a bolt into the battery port and wrapped a piece of wire around it. I touch the other end of this wire to the battery cable that is hanging disconnected. Amperage is so high wire tends to stick/weld to the cable connector. Please advise

 

What you may be seeing when you first connect the battery is the normal several amps draw that can really spark. The amp draw will go down as the BCM goes into sleep mode. Without measuring the actual draw it is hard to tell.

Were you getting the clicking when the ignition was OFF and you connected the battery?

To determine if you have a draw beside the lights, keep the lights/motors unplugged and measure the battery voltage at the battery. Let it sit for 6 hours and measure it again. do this for several times to see if you really another drain issue.

If you want to discuss your issue over the phone at some point feel free to PM me.

 

The amp draw goes down. So looks like it's not a problem. Ignition was off all the time and the clicking positively was coming from the headlight motor. I'll check the voltage drop as you recommended as soon as I can
thanks a lot

 

Will look into why just the passenger the motor would try to run when the ignition is OFF.

 

I have looked at the schematics.

The MF switch powers/tells the Headlight Module whether the lights should ON or OFF.

The Headlight Module is ALWAYS HOT meaning it is always powered even when the ignition is OFF. This is separate(in addition) to the one circuit from the MF switch discussed above.


I think the Headlight Module has failed since it sends 2 separate signals out, one for each motor. I think it has failed on the passenger side.

We know the right motor is getting powered with the ignition is OFF and you can unplug it and the clicking does not occur.

Let's see if anyone else has another idea. Let me know if you need the schematic or any other help.

 

I don't know if it's the passenger side only. That's the only side I was able to check since I had to be by the battery and the same time put my hand on the motor. But I can get somebody to help me and check the LH side motor or just disconnect the rh side and listen if I hear a click from the LH side

 

Even if both sides do it, I can't think of any other reason for it other than the module.

 

I did some additional checking today. Clicking comes from the RH side headlight motor only. After I disconnected both headlights and connected cable to the battery port I could hear a sound coming (I think) from a point between the engine and the firewall. Every time i touched the port I heard this sound for a second or second and a 1/2. It sounded like an actuator. I measured voltage. it was 11.9V. Nine hrs later it was 0.7V. As I said both headlight were disconnected.

 

I don't know what you mean by "port". Also was 11.7 to .7 battery voltage measure at the Battery?

If you want to discuss over the phone just PM me with your number. Otherwise we can continue here on the Forum.

The C5 does NOT like low voltage. Here is some info that may help.


A fully charged battery should be 12.6v or more.

It's not 12 volts it's 12.6 because each cell is 2.1 volts.

If the battery is

12.5 = 85% charged
12.4 = 65%
12.3 = 50%
12.2 = 35%
12.1 = drained

 

battery port is the same as terminal, where you connect cables. I measured voltage at the terminals. my phone number is 248 933 3959 if you don't mind calling. My name is Ted

 

hi Sam,
it got a bit warmer again so I measured current. At first it was 12.5 A. Later it was about 8.5 A. I disconnected alternator. No affect. I disconnected red wire going from battery to fuse box. Got 0 A. Next I reconnected the red wire back to the fuse box but without the other red wire that was on the same stud. I guess it goes to the fuse box on the floor. Got 0 A readout. It puzzles me because the first time I was trying to find the problem I removed all the fuses, one by one, from the floor fuse box and didn't see any effect. So what's next? If you have time and don't mind calling me again my number is 248 993 3959

 

When reconnecting battery there will always be an immediate draw and clicking going on when systems wake up and reset.
my suggestion - unhook positive battery cable / grab a fog light or facsimile that can easily be seen and wire between disconnected positive cable and positive battery post / light should be fairly bright at first due to the start up draw then should dim to almost nothing / if it stays bright(ish) start pulling fuses until draw goes to very dim (you will always have a little draw due to computer, radio, clock etc.). the fuse that drops the draw is where you need to go to fix the problem or leave the fuse out if not important - mine was the lumbar fuse for my p/s sports seat - just wants to keep on keeping on.

 

Hey Sam I know it makes things much more effective for you to be able to discuss on the phone symptoms/diagnostic/testing etc. and then threads like this one sometimes are left open...
Would you be willing to come back when you can and post what the outcome was via your phone conversations with that specific issue...
Thanks... steve

 

Will call you but if I understand what you did your drain is in the passenger fuse box.

Steve, Ted and I will close the loop with a summary.

 

Thank you sir

 

First of all I apologize for the wrong number. It should be 248 933 3959.
Before I call you and take your time let me do some additional checking. As I wrote you, looks like it's something connected to the floor fuse box that's causing the problem. Can I do what you advised with a small change? What If I connect the amp meter then start pulling the fuses. When I pull the right one measurement should drop, right?

 

Yes you can do that, don't forget about the circuit breakers. Don't pull the BCM fuses as that will take it out of sleep mode. It could be the BCM but I think you will find the circuit without needing to pull any.

 

Tried to return your call and leave a message but you still don't have a voice mail box setup.