WH Caprice radio drains battery

[PlainSailing]

The history of this fault: I started the motor while the radio was turned on, then noises came from the rear speakers; sounded like a possum in the boot. Then lots of smoke poured from the radio from around the "audio" knob. The radio was replaced but the same problem occurred again after 5 days. The rear speaker leads were disconnected but now the radio drains the battery overnight. Both radios still work using just the front speakers but both drain the battery. Any suggestions about this major mystery?

 

[myberlina]

Were the rear speaker leads disconnected before the second unit went up in smoke? If not, then I would think there is a serious wiring issue. Maybe test the rear speaker leads for voltage?

Perhaps try disconnecting the rear speaker amp? Perhaps there is also a fault within the amp that is some how sending electricity back into the head unit causing this problem.

Where there is smoke there is fire so I wouldn't let Holden screw around for time to fix it.

Hope my ideas are of some help.

 

[SMIT]

Sounds like you have 2 inputs going to the speakers which would make the h/u smoke.

 

[PlainSailing]

No, the rear speakers were disconnected after the 2nd unit went up in smoke. I think you've summed it up correctly, but until I find out for sure why the head units become faulty I don't want to replace it again. Thanks for the guidance.

 

[PlainSailing]

What do you mean by 2 inputs going to the rear speakers?

 

[holdenboy]

I would personally be testing the wiring before fitting a new unit. Get yourself a multimeter and test the speaker wires for their impedance (should be 3.5 - 4.5 ohms) and check the power/earth wiring too.

Could even be a problem with the rear amplifier. How did you disconnect the rear speakers?

 

[PlainSailing]

After the 2nd head unit was fitted an Auto Electrician spent hours chasing a short circuit towards the rear of the car then the short disappeared (so it's an intermittent fault); He said he couldn't see any sign of a problem ie, wiring caught up under a metal clamp or similar. From what I'm being told I'm thinking the rear amp, but without knowing for sure a new head unit is a costly test, if I don't pick it right or can't test the fault for sure. The Auto Electrician simply cut the rear speaker leads before they go into the head unit, at the plug/socket. (yeah! I know! Bit rough!) I'll get a meter onto it & try to find something as you've suggested. Thanks for the ideas. This is not my line of skill! :>)

 

[PlainSailing]

Just in case it helps someone else who gets the same/similar symptoms, the problem of the smokin' head unit was traced to a short circuit in one of the rear door speakers. This was discovered while a professional was installing a different radio/stereo and rear woofer amp. I use a memory stick instead of CD's and it sounds brilliant. And never caught short of music!
Thanks for the help from this site - it made a big difference.