My 88 4Runner is having a problem I can't figure out. Not always, but quite often, when I press the brake, use turn signal, or turn on lights while driving, my radio cuts out momentarily. I also noticed that the lights sometimes get brighter and that makes it cut out also. And sometimes when I hit a hard bump it happens. Alternator? That's the only thing I can figure. Would the stereo be drawing that much power?

It is aftermarket Sony Xplod with Xplod speakers. I noticed all this on a 3500 mile drive the last week around the country and didn't notice it before. Any help appreciated.

 

Sounds like a loose connection. I'd lean towards a bad ground. Troubleshooting wiring harness in such an old truck would be a pain so the easiest would be to ground the radio to a new spot and see if it does it again.

 

ground to body of head unit

 

I agree...sounds like something causing a short. Bad ground can sometimes create a gap in the insulation of the wire...so also watch out for that. When I bought my rig, the turn signal fuse would constantly blow until I figured out that the trailer harness wiring was shorting on the rear bumper. I got the ends secured only to have that same fuse keep blowing. I ran the wires and sure enough there was a section of exposed wire shorting on each other. Wiring is a PITA, good luck.