I posted this on another site but maybe I can get advice here,

I have a 4ch rockford P400-4 set to 2ch and using two alpine 4ohm 6.5's. Everything had been working fine but lately say I am driving to work for about five minutes then I turn on radio you can feel the car kind of shudder a bit then after awhile of the radio playing the amp goes into thermal protect. The gains are under a quarter turn from zero and made sure the ground is good. Any ideas?

today i changed rca cables left them disconnected tried different ground left speakers off the amp ran a new remote line and even ran everything directly to head unit and still amp overheats even with gains all the way down.

Do you have another amp you can hook up to test?

I had a P1000 - 1bd in the car also

rockford 1/0 gauge from a XS Power S3400 under the hood to the trunk distro block and about a foot of 4 gauge power and ground to each and also 90 amp alt with big 3 done. I stripped everything down to just head unit and P400.

voltage at battery is at 14.1 to 13.8 and the same at the amp. if I hook up the P1000 - 1bd by itself everything is fine.

Edited October 26, 201014 yr by crunkjuice1

Do you have another amp for your highs you could hook up.

Trying to confirm or eliminate the amp as the culprit.

You say you have two alpine 4ohm 6.5's. One set per channel or two?

amp is set to 2ch with just two speakers but this happens with nothing but remote power and ground connections to amp. Its like this amp puts a strain on car when it powers up

Edited October 26, 201014 yr by crunkjuice1

they are not parallel

I rechecked everything I have done and now I have everything off car. Last thing I can add is that the RCA jacks on the back of radio were hot. My radio only has two rca outputs (front, rear) but I can change the rear to sub output which is the way I had it so to draw a picture the connections were like this,

front rca to main input on EQ

subwoofer out to subwoofer in on P1000

front out on eq to front in on P400

nothing wrong on the P1000 side

P400 makes car idle erratically when it first turns on even by itself and no speakers wired into it.

could have bad head unit rca's messed up the P400?