# Aftermarket Head Unit drains my battery



## Bierkan (Aug 5, 2009)

Recently bought an aftermarket head unit for my 2000 Golf GLS (with Monsoon). Alpine CD player with front USB. The stock radio had 3 plugs that I disconnected. I bought the new stereo from Crutchfield so they sent the a wire harness and antenna adaptor. The harness from Crutchfield only had 2 plugs. I called and asked and they said the 3rd plug was for the optional CD changer which I do not have.
I installed the new radio on a Saturday monring per the instructions provided. The radio worked well, however, Monday when I went to leave for work my battery was dead. I jumped the car and it ran for about 15 seconds before sputtering and dying...battery dead once again. I removed the battery and had it tested at local parts store. It checked out OK. I pulled the alternator and took to the store for test. It ran only 12V and sounded like brushes or bearings worn so I bought a new alternator and reinstalled. Jumped the car again it ran good. I let it run 10-15min to charge battery and turned it off. When to leave 3 hours later and battery dead again!! Pulled the radio, disconnected the plugs to the amp in trunk, and jumped the car AGAIN. Took the car for a drive and it ran great. Waiting a few hours to see if pulling radio/disconnecting amp removes the drain on the battery.
Has anyone else had this kind of problem installing aftermarket radio? What could be draining the battery?


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## twelvevolt (Oct 29, 2003)

*Re: Aftermarket Head Unit drains my battery (Bierkan)*

your switched power line (the red one) is probably hooked up to a constant power line, and not shutting the radio off when you pull the key out. this wire should have 12v when the key is on, and nothing when off.


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## Bierkan (Aug 5, 2009)

*Re: Aftermarket Head Unit drains my battery (1sik95jetta)*

Double checked the wires and everything is correct. Radio shuts off when key is removed. My guess is the Monsoon amp is not shutting off when the radio shuts off. I know on aftermarket amps the amp is turned on/off with the remote antenna lead from the radio. Not sure what lead does this on the Monsoon.


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## K101 (Jul 29, 2009)

*Re: Aftermarket Head Unit drains my battery (Bierkan)*

If you have the correct harness, your problem should not have to do with the monsoon amp. That amp turns on and off automatically when it senses speaker line signal input or absence thereof. I'd double check the harness again....but it sounds like you have the power hooked up correctly.


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## TBT-Syncro (Apr 28, 2001)

*Re: Aftermarket Head Unit drains my battery (Bierkan)*

you probably have the K wire hooked up (it should not be).


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## Bierkan (Aug 5, 2009)

*Re: Aftermarket Head Unit drains my battery (TBT-Syncro)*

What is the K wire? Could this be related to the antenna.
Crutchfield sent an antenna adaptor and it had an extra blue lead. I did a little research and I thought that was for an amplified antenna (for AM reception). I connected the remote antenna lead for the radio to this blue wire on the antenna adaptor. Is this the K wire? Could this be draining my battery when the radio is off?
Thanks all for the help!


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## ibanezbassistgsr (Mar 4, 2009)

*Re: Aftermarket Head Unit drains my battery (Bierkan)*

ive had a similar issue... double check all the wiring... this is nothing like the other guys were saying but my left speakers were flopped from rear and front... those were the ONLY wires connected wrong... swapped em to be correct and havent had a prob since *knocks on wood* just figuredi d put my 2cts in and see how it works...


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## Bierkan (Aug 5, 2009)

*Re: Aftermarket Head Unit drains my battery (ibanezbassistgsr)*

Well I double and triple checked my wiring pinout diagram on top of factory radio and it checks out. Also, checked pinouts in jumper harness to make sure harness wasn't defective. Interesting note diagram on factory HU indicates that the RR+ terminal is for Monsoon amp. I assume that means that channel turns amp on/off. Also on 3rd plug, that is for optional CD changer (or so I am told), there is a terminal labled "Ext Amp".
Bottom line, after hours of internet research on this topic as well as time spent in the dash of my car I am giving up. Apparantly the Monsoon amp is picky with voltage required to turn off. I put the factory HU back in and battery does NOT drain. Sent the Alpine unit back to Crutchfield for refund. This little experiment cost $15 (box and shipping to return HU).
I do not understand the necessity for the level of complexity in the Monsoon design??? Or why VW was still putting in dash cassette decks in vehicles in 2000??
Anyway thanks to all that pitched in and offered help! Does anyone know of a VW CD changer for sale? Or are there aftermarket CD changers that will work with factory HU (You would think I would have learned my lesson)?


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