Hello I have a 2004 model commodore with a Pioneer DEH-P7750MP head unit, Pioneer TS-C1625 split's front and rear running off a Pioneer GM-6100f 4 channel, 60 watts X 4 rms output Amplifer. Only when the engine is running on songs with high treble at half volume the amp cuts out for a couple of seconds then back on then off and continues until the volume is turned down. This has been checked by an auto electrician with car audio experience. Every thing from the head unit wiring and voltages have been checked which are all ok. the amplifer has been replaced under warranty but the problem is still there. The amplifer has been changed to another brand amlifer were the problem did not occur but when the pioneer amp was put back in the problem started again. As far as i can tell there is a problem in the amp. Can someone please give me some hints on what to do Thanks.

well if you changed amps, and it worked with the other amp. wouldn't it be common sense to say that ur amp is stuffed.

thats my idea anyway

Was the amp checked out by Pioneer, and then returned to you with "no fault found"?

Probably better off in general discussion.

Sounds like the amp may be faulty. but also sounds like a low voltage problem I know many amps will turn off at low voltage then back on when voltage is restored. What size wire are you running? is the HU turning off too or just the amp? the bit that confuses me is the treble (because normally this typen of problem is caused by bass) and only when the car is on (by on u mean running yeah?) if the car is reved slightly above idle does it still happen?
does the amp get warm ?
does it happen straight away or after a while of listening?

i'd suggest its a power (i.e. low-voltage) issue

possibility it could be speaker wire shorting?

- Stooge007 out