I have a .5+ amp draw on my battery with the car off. I have checked the dome light switch and it is in the off position. I did an amp draw test (remove the positive terminal and put an amp meter inline) and it pegged my meter, which is .5 amps. I started pulling fuses and relays to see what system had the the draw and did not find one that would return it to zero.

Is there any systems that don't run through the main fuse panel that I might be missing? Is the starting system an inline fusible link? Has anyone had any similar issues?

 

Awesome write up! I appreciate the info. I will make sure to check the other fuse box as well. When I connect and disconnect the terminals I can hear what sounds like a relay click in the front of the car. I was thinking headlights or starter. I will continue the search.

 

I will give that a look too. He says if it's warm to the touch that it's bad.

 

8Vette7, I'd like to ask a question as well that will surely be in line with the purpose of this thread. I've got a draw on my system that I'll be chasing soon, same as the OP here. I'll be using BC's method from your link above (the famous post #590). I see that opening the door to get to the passenger foot well fuse box will reset the 15-20 min sleep mode in the BCM, therefore requiring another wait of 15 minutes or so to wait for the BCM to go to sleep again then pull the next fuse..etc..etc. Is there a way to keep the BCM from knowing that you've opened the door? For example, older cars had a plunger switch that was pushed in when you close the door. When you opened the door, the domelight would come on because the plunger wasn't pushed in anymore and it would go out when you closed the door. You could tape that switch down and open the door and your domelight would not come on, thus sort of "fooling" the car into not knowing the door had been opened. Can we do the something similar on the C5?

 

Thanks Chuck. I continue to learn new stuff every day. So much appreciate your knowledge and willingness to share said knowledge. One of these days I'm going to drive to Arizona and buy you a cold tall one.

 

My C5 corvette had been draining the battery to the point that in few days it was not able to start the engine and I had just about 2 year old good battery.


Quick & Dirty:

As a workaround I installed the battery maintainer inside the car and whenever coming back home I hooked it up so the battery would never drain.


Final Major Solution – replacing the driver power seat switch board assembly (Seat multifunction switch & Lumbar Switch):

I also did some troubleshooting connecting Amp meter between negative battery connector and car ground. I run long isolated cables so I could watch the meter in passenger feet area where internal Fuse Block Compartment is. After car went into sleep mode after about 15 min I found that Idle current is 0.4A (or 400mA). That is between 10 to 20 times more than expected!

To my surprise pulling the fuse 4 – Driver Seat Control Module the current dropped from 400mA to 40-50mA.

Further investigating I put the fuse back and disconnected the white connectors under the seat that is providing power to the lumbar cushions inflators (1 air pump in one pouch & 3 valves / solenoids in the second pouch).

Yes, it was that system draining the battery but why? There was no noise nor any indication something is wrong.

Here is the answer:

Either someone or the air pump by itself had disconnected wires to the motor therefore there was no any noise. However the power seat lumbar inflating switch was stuck in ON position. As soon as I connected motor the pump started pumping in a stuck position.

So what was draining if the motor/ pump was disconnected?

It was a combination of stuck inflator switch that was also activating one of 3 valves / solenoids.

That solenoid / valve was continuously consuming additional 350-360mA!

There is a person/company called Vettetronics on EBay offering service to fix that switch board for you for $84.99 if you send him your faulty one. Service is called: “C5 Corvette Power Seat Switch REPAIR SERVICE LH or RH '97-'04 WE FIX FAST!!!”

It seems like this service is popular because EBay says: “73 sold”.

I have just shipped to him my faulty switch board.

To make sure I got it right I removed that switch board from passenger side and moved it to driver side (they are identical) and everything is working fine now and idle current is now between 40 & 50 mA.



Final Minor Solution – additional switch for the radio with an iPOD/iPhone support: NEO or iSimple PXDP

So now down to 40-50 mA. If I remove the fuse 5 – Radio. The current drops down to expected 25mA.

This is not significant but if you park your Corvette for several weeks without battery maintainer it will shorten your battery capacity in half. Someone mention that brown color wire in the harness is responsible for power supply to NEO or iSimple therefore making a switch inline and running the wires to some convenient place where to place a switch might be a good idea.

If you are too lazy to go behind the radio to get access to the harness to just cut power only to NEO or iSimple you can also buy “Mini add-a-circuit holder” by Littelfuse and install it instead of Radio Fuse 5. This way you cut power to both Radio and NEO/ iSimple. The drawback is that your clock in the Radio will also be reset each time you flip the switch.
Just make sure you are using only upper fuse position with radio fuse (fuse is inline in upper position and in parallel in lower position) and extend the wire to the switch and run it back to lower fuse position to close the circuit.

I hope this will be helpful to someone.

Let me also know if someone needs any pictures of components I mentioned above.

Good Luck !