Stock amplifier draining battery

rekrull · #1 08-15-2005, 10:03 PM

I have a 98 GT with the stock "premium" CD stero system. The battery is dead after the car has been sitting for about 6 days or so. I've been able to identify the source of the battery drain as the audio amplifier located just under the glove box. I've tried a new amp, and this does not seem to have changed anything. Does anyone have a wiring diagram for this or know where the power for this amp comes from? I was able to get some info from the dealer on this circuit, but it doesn't even mention the amplifier.

Thanks!

BNaylor · #2 08-16-2005, 11:05 AM

Quote:

Originally Posted by rekrull

I have a 98 GT with the stock "premium" CD stero system. The battery is dead after the car has been sitting for about 6 days or so. I've been able to identify the source of the battery drain as the audio amplifier located just under the glove box. I've tried a new amp, and this does not seem to have changed anything. Does anyone have a wiring diagram for this or know where the power for this amp comes from? I was able to get some info from the dealer on this circuit, but it doesn't even mention the amplifier.

Thanks!

Is your Retained Accessory Power (RAP) system working? If you leave the stereo system on and then open the door does it go off? The amp may get power via the RAP relay and associated circuit. Maybe a contact is bad causing an improper turn off and the battery drain.

I'll check my GP service manual for you when I get a chance.

Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 104s,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials

wylie · #3 08-16-2005, 11:09 AM

How old is that battery?
the olny drain on the battery when its sitting is the security system
And thats very little,I've left my 99 sitting for weeks and it fires up
like it still has a full charge.
.
.

rekrull · #4 08-16-2005, 11:24 AM

I'm not sure where the RAP is located. I'm guessing that it is somehow involved. What I've found is that the power does shut off to the dome lights and radio, but there is still a 100 mA draw on the battery when the radio shuts off. With the amp unplugged it goes down to ~20mA which is normal. It seems as though I can only reproduce the high current draw in certain situations. If I sit in the car and wait for the relay to shut off I see the higher current draw. If you exit the car or use the remote to lock the car I cannot measure the higher draw, although the battery still dies. Unfortunately I don't have a way of recording the current draw over time. With the amp remove everything is fine.

I have installed a new battery. No change. I even built a test circuit that had 20mA current draw The battery was fine.

BNaylor · #5 08-16-2005, 02:56 PM

Quote:

Originally Posted by rekrull

I'm not sure where the RAP is located. I'm guessing that it is somehow involved. What I've found is that the power does shut off to the dome lights and radio, but there is still a 100 mA draw on the battery when the radio shuts off. With the amp unplugged it goes down to ~20mA which is normal. It seems as though I can only reproduce the high current draw in certain situations. If I sit in the car and wait for the relay to shut off I see the higher current draw. If you exit the car or use the remote to lock the car I cannot measure the higher draw, although the battery still dies. Unfortunately I don't have a way of recording the current draw over time. With the amp remove everything is fine.

I have installed a new battery. No change. I even built a test circuit that had 20mA current draw The battery was fine.

Its possible but it looks you have a good handle on the situation especially from your troubleshooting technique. The RAP relay should be located on the passenger side of the dash near the fuse box assembly. When the stereo/radio shuts off you can hear it it clunk/click.

According to the wiring diagram the low frequency amplifier gets an enable signal called "Amp On Input" at Pin A5 of the amp input. It should be color coded pink. The ground is Pin A9 - black/white. The other primary line I see feeding the amp is "IGN POWER" Pin A12 - Orange.

Its looks like the control of the amp is provided by the stereo/radio head unit. "AMP ON" originates at connector C2, Pin 12 - Pink of the head unit. You might try disconnecting that specific connector and then see how the current draw is. The other connector on the head unit is C1.

The other line of interest would be at connector C1, Pin 10 which is called "BATTERY POWER". Its an Orange wire and is an input to the stereo/radio.

Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 104s,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials

rekrull · #6 08-16-2005, 04:10 PM

Thanks for the wiring info!

Now that I think about it (I've been struggling with this for a while), I did try disconnecting that (RAP) relay. I didn't see any change on the current draw.

Something is weird here though. If the amp gets the signal to turn on from the radio, then if the radio is unplugged the amp should shut off. I had the radio unplugged and saw no change in the current draw. Is there a relay in there somewhere?

BNaylor · #7 08-16-2005, 07:33 PM

Quote:

Originally Posted by rekrull

Thanks for the wiring info!

Now that I think about it (I've been struggling with this for a while), I did try disconnecting that (RAP) relay. I didn't see any change on the current draw.

Something is weird here though. If the amp gets the signal to turn on from the radio, then if the radio is unplugged the amp should shut off. I had the radio unplugged and saw no change in the current draw. Is there a relay in there somewhere?

The wiring diagram does not show any relays between the amp and head unit, only wiring and connectors. There could be mini-relays within each component. It shows power 12v coming directly from fuses based on RAP or the ignition switch in the RUN or ACC positions. Send me a PM email with regular email address and I might be able to send you the one page wiring diagram.

The common point appears to be IGN POWER at the amp and BATTERY POWER at the head unit in which both directly feed off the 15 amp fuse called RADIO FUSE in the engine compartment fuse block. There is a note that says HOT AT ALL TIMES.

Thrasher CAI, DHP v1.0 PCM, SLP Headers,
3.25 SC pulley, CAIT GMAF, 2.5 DP/Hi-Flow CAT,
u-bend delete, 160 TS, ZZP Stage 1 72mm TB,
TB spacer, MSD 8.5mm wires, Autolite 104s,
Goodyear Gatorback Serp. & SC Belt,
Nitto NT555R Drag Radials

rekrull · #8 10-10-2005, 10:58 AM

I never was able to determine why this thing was draining the battery. Once I got a wiring diagram I was able to move the 12V power from constantly on to a source which was only on with the key on.
It appers to be OK now. After 2 weeks at the airport, the car started no problem.
Thanks everyone for your help!

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