Need help - Electrical problem = draining battery =(
Thread Starter
Instructor
Joined: Oct 2004
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From: Lawrence KS
Need help - Electrical problem = draining battery =(
The HVAC controls that are backlite in the interior of the car will not turn off 
The lights stay on when the car is shut off and they never turn off! Any idea what the deal is? The car has an aftermarket sub and amp and it also has dual aftermarket heated seats. I disconnected the amp to see if that was the problem - it wasn't the lights stayed on. I haven't been able to track down where the heated seats wires are yet - anyone think they're to blame?
I've been pulling the fuse for the HVAC controls (fuse 27 on diagram) to keep the lights from draining my battery but for some reason with that fused pulled my factory car alarm doesn't work
what does the HVAC controls have to do with the car alarm?
Car - 2000 C5 coupe
Thanks for the help!
The lights stay on when the car is shut off and they never turn off! Any idea what the deal is? The car has an aftermarket sub and amp and it also has dual aftermarket heated seats. I disconnected the amp to see if that was the problem - it wasn't the lights stayed on. I haven't been able to track down where the heated seats wires are yet - anyone think they're to blame?I've been pulling the fuse for the HVAC controls (fuse 27 on diagram) to keep the lights from draining my battery but for some reason with that fused pulled my factory car alarm doesn't work
what does the HVAC controls have to do with the car alarm?Car - 2000 C5 coupe
Thanks for the help!
Race Director
Joined: Aug 1999
Posts: 17,541
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From: Manhattan, KS Missing SoCal since 2005
Hard to say what was done with the aftermarket stuff added to the car - it's probably going to take an electrical expert to trace what was done & get it sorted out. I had the same problem with my '85 - an aftermarket security system that was draining the battery. I dropped the passenger side knee bolster and a big ball of wiring, control boxes, etc. fell out! At that point, I called in the pro's....
Where in KS are you located? We are moving back to Manhattan soon.
Where in KS are you located? We are moving back to Manhattan soon.
Race Director
Joined: Nov 2003
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From: Mustang OK
Originally Posted by thevettenet CA
Hard to say what was done with the aftermarket stuff added to the car - it's probably going to take an electrical expert to trace what was done & get it sorted out.
Good luck with the problem. 
Safety Car
Joined: Dec 2002
Posts: 4,010
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From: SE Idaho
St. Jude Contributor
Fuse 27 supplies Battery + voltage to the HVAC control head and the remote control door lock received...reason the alarm will not operate.
I'm guessing that who ever installed the amp or heated seats might have tapped into the circuit (Orange wire) running from the fuse block to the HVAC. When you pull fuse 27 does it also turn off the amp and the heated seats?
What happens when you pull fuse 18, which is the 10 amp fuse that protects the ignition On circuit to the HVAC head? This is actually the circuit that controls the HVAC lights illumination, since power off 27 is always available. They may have tapped into this wire for ignition On power.
Fuse 18, circuit 41 also supplies power to the HVAC control actuators and valves, blower motor, and the power feed to the coil of the rear defog relay. Pulling this fuse should also shut off the HVAC lights, but won't disturb the alarm. If, removing this fuse does not kill the lights, that would be a good indication there is a problem in that circuit.
To be honest, it is rough diagnosing an electrical problem in person, over the Internet it gets harder, but with all the aftermarket items added, it can be a nightmare.
I'm guessing that who ever installed the amp or heated seats might have tapped into the circuit (Orange wire) running from the fuse block to the HVAC. When you pull fuse 27 does it also turn off the amp and the heated seats?
What happens when you pull fuse 18, which is the 10 amp fuse that protects the ignition On circuit to the HVAC head? This is actually the circuit that controls the HVAC lights illumination, since power off 27 is always available. They may have tapped into this wire for ignition On power.
Fuse 18, circuit 41 also supplies power to the HVAC control actuators and valves, blower motor, and the power feed to the coil of the rear defog relay. Pulling this fuse should also shut off the HVAC lights, but won't disturb the alarm. If, removing this fuse does not kill the lights, that would be a good indication there is a problem in that circuit.
To be honest, it is rough diagnosing an electrical problem in person, over the Internet it gets harder, but with all the aftermarket items added, it can be a nightmare.
Burning Brakes
Joined: Nov 2001
Posts: 869
Likes: 0
From: Nashua NH
On a 2003 wiring diagram (sorry but that's the only year I have), F27 controls power to the HVAC control module and the Remote Control Door lock receiver. Maybe that is the connection with the alarm or else your car is wired differently.
Melting Slicks
Joined: Sep 2004
Posts: 3,024
Likes: 18
From: DFW Texas
If you have an aftermarket head unit, and your amp is on one fused circuit and the head unit (memory wire - usually yellow), what has happened, is the amps have actually shorted into the head unit and THAT is what is running the batt down.
I had a Tahoe with Kenwood Sirius unit. Worked great then started a very slight pop sound when I turned the ignition off. The slowly at first the batt would go dead. Thought for sure it was amps, so disconnected them - no luck. Removed all wiring from the amps - speakers and the trigger wire.. Still nothing. By this time, the batt was going completely dead in less than 18 hours.
Pulled the head unit out, connected to a remote batt, and when the yellow (station memory, clock, setting, etc) wire touched a positive source, it made a pretty good spark. I then knew it was the head unit.
Contacted Kenwood, and they said was a common problem. Wanted $85 to fix - put stock radio back in - YAWN - oh well.
BTW. Had many friends (and me too) with wakeboard boats all decked with 3 and 4 amps, 3 and 4 batteries, caps, crossovers, driving up to 12-16 speakers + 2 subs... was a constant battle of replacing parts so batt's would not go dead. (I now longer own a wakeboard boat!)
I had a Tahoe with Kenwood Sirius unit. Worked great then started a very slight pop sound when I turned the ignition off. The slowly at first the batt would go dead. Thought for sure it was amps, so disconnected them - no luck. Removed all wiring from the amps - speakers and the trigger wire.. Still nothing. By this time, the batt was going completely dead in less than 18 hours.
Pulled the head unit out, connected to a remote batt, and when the yellow (station memory, clock, setting, etc) wire touched a positive source, it made a pretty good spark. I then knew it was the head unit.
Contacted Kenwood, and they said was a common problem. Wanted $85 to fix - put stock radio back in - YAWN - oh well.
BTW. Had many friends (and me too) with wakeboard boats all decked with 3 and 4 amps, 3 and 4 batteries, caps, crossovers, driving up to 12-16 speakers + 2 subs... was a constant battle of replacing parts so batt's would not go dead. (I now longer own a wakeboard boat!)
Burning Brakes
Joined: Nov 2001
Posts: 869
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From: Nashua NH
As was said, since the F27 circuit is aways hot, it seems like it would not be the actual case of the problem. My book says that the interior lighting control (dimming) is actually coming from the BCM.
Does the HVAC stay bright if you dim the console lights?
Does the HVAC stay bright if you dim the console lights?
Burning Brakes
Joined: Nov 2001
Posts: 869
Likes: 0
From: Nashua NH
The BCM is also supposted to cut power to the interior lights after a time out. I wonder if someone got a hot wire crossed/shorted with the dimmer wire to the HVAC control. This could account for the lights be on all the time and draining the battery. Otherwise it may be the BCM. I think the first option may be more likely.
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Thread Starter
Instructor
Joined: Oct 2004
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From: Lawrence KS
Originally Posted by Sandy S
As was said, since the F27 circuit is aways hot, it seems like it would not be the actual case of the problem. My book says that the interior lighting control (dimming) is actually coming from the BCM.
Does the HVAC stay bright if you dim the console lights?
Does the HVAC stay bright if you dim the console lights?
Yes I can not dim the HVAC controls. They are always bright and will not dim at all.
Thread Starter
Instructor
Joined: Oct 2004
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From: Lawrence KS
Originally Posted by diyguy
If you have an aftermarket head unit, and your amp is on one fused circuit and the head unit (memory wire - usually yellow), what has happened, is the amps have actually shorted into the head unit and THAT is what is running the batt down.
No my C5 has the factory CD/Radio face. It does not have an aftermarket face.
Thread Starter
Instructor
Joined: Oct 2004
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From: Lawrence KS
Originally Posted by Sandy S
Have you looked for non-factory wires spliced into the BCM? It is located under the false floor in front of the passenges feet.
Yes there are non-factory wires under there but I don't know what (if any into anything) they're spliced into. I assume they are the heated seats wires because they are very small wires (I'm assuming the amp/sub wires would be bigger wires since they would carry more current).
Thread Starter
Instructor
Joined: Oct 2004
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From: Lawrence KS
Originally Posted by Sandy S
The HVAC dimmer is a yellow wire but I think there are more than one yellow wire. What color wires are spliced into?
Give me about 30min's or so and I'll go check (I'm at work so I gotta make some time to slip out for a sec).
Burning Brakes
Joined: Nov 2001
Posts: 869
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From: Nashua NH
Looks like there are 3 yellow wires to the BCM (remember I am looking at a 2003 wiring diagram and it may not match your car).
Connector C2 has 1 yellow wire. It is hot when accessory is on.
Connector C3 has 2 yellow wires. One goes to the HVAC lights and the other goes to the Front Fog Lamp indicator Control.
There are several wires that are yellow with some other color stripe so don't confuse them.
Connector C2 has 1 yellow wire. It is hot when accessory is on.
Connector C3 has 2 yellow wires. One goes to the HVAC lights and the other goes to the Front Fog Lamp indicator Control.
There are several wires that are yellow with some other color stripe so don't confuse them.
Thread Starter
Instructor
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From: Lawrence KS
Originally Posted by WhiteC5Vette
What happens when you pull fuse 18, which is the 10 amp fuse that protects the ignition On circuit to the HVAC head? This is actually the circuit that controls the HVAC lights illumination, since power off 27 is always available. They may have tapped into this wire for ignition On power.
Fuse 18, circuit 41 also supplies power to the HVAC control actuators and valves, blower motor, and the power feed to the coil of the rear defog relay. Pulling this fuse should also shut off the HVAC lights, but won't disturb the alarm. If, removing this fuse does not kill the lights, that would be a good indication there is a problem in that circuit.
To be honest, it is rough diagnosing an electrical problem in person, over the Internet it gets harder, but with all the aftermarket items added, it can be a nightmare.
Fuse 18, circuit 41 also supplies power to the HVAC control actuators and valves, blower motor, and the power feed to the coil of the rear defog relay. Pulling this fuse should also shut off the HVAC lights, but won't disturb the alarm. If, removing this fuse does not kill the lights, that would be a good indication there is a problem in that circuit.
To be honest, it is rough diagnosing an electrical problem in person, over the Internet it gets harder, but with all the aftermarket items added, it can be a nightmare.
Pulled fuse 18 and it didn't do anything. The HVAC backlight was still on the amp still worked and so did the heated seats.
Thread Starter
Instructor
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From: Lawrence KS
The amp still worked with fuse 27 pulled. However the amp would lose power if I would shake the bundle of wires under there (there are a lot of wires under there! not inluding the wires coming out of the BCM...something's not right...).
Thread Starter
Instructor
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From: Lawrence KS
Originally Posted by Sandy S
Looks like there are 3 yellow wires to the BCM (remember I am looking at a 2003 wiring diagram and it may not match your car).
Connector C2 has 1 yellow wire. It is hot when accessory is on.
Connector C3 has 2 yellow wires. One goes to the HVAC lights and the other goes to the Front Fog Lamp indicator Control.
There are several wires that are yellow with some other color stripe so don't confuse them.
Connector C2 has 1 yellow wire. It is hot when accessory is on.
Connector C3 has 2 yellow wires. One goes to the HVAC lights and the other goes to the Front Fog Lamp indicator Control.
There are several wires that are yellow with some other color stripe so don't confuse them.
From what I could see there was only 1 wire spliced from the BCM - a brown w/white stripe wire coming from the top (nearest the glove box) of the BCM.
None of the yellow wires were spliced. Perhaps given the model year difference between your manual and my C5 the wires are different colors and/or have different purposes.
I'm going to take a pic of the wires under there for you guys to check out since I really don't think there should be that many wires under there. Hopefully I'll get a pic on here by midnight or so.