Expert: Peter G. Lee - 8/4/2006

Question
93 honda prelude, I have aftermarket cd unit and speakers. I installed all units successfully,   a month after installation the speakers started to stop playing off and on. Now they don't play unless I hit a bump on the road but then stop shortly after. I checked all speaker wiring by redoing the wiring to the speakers to make sure there were no lines crossed. I tried another working headunit and a new wiring harness. Nothing has worked. Both cd players have shown that music should be playing by having the time in the songs go by. I have also tried using the car radio instead of a cd. Any suggestions would be great.

Answer
O.K. lets apply a bit of Vulcan logic here.
“All speakers go off” means a COMMON problem so unlikely to be anything to do with speakers or their leads and we should be looking at a common fault.

“Goes off after hitting a bump”, apart from saying “Don’t hit bumps”, it must be something loose that move under such conditions.

“Tried another unit and harness”, so eliminate those, which leaves?

Think about it, not the speakers or speaker leads as they would be a one off, not all four. Not the head unit or harness as they have been swapped so it must be up line from the head unit and a fault in the loom / fuse box of the car, can’t be anything else really.

Try carefully hooking up a temporary pair of wires directly from the battery connections to the head units earth lead and the two positive leads on the head unit connector, (live and acc together so radio is “on” all the time) and go find some bumps.
If it remains the same and drops out on bumps then you know the problem lies in the head unit or output, if it cures it then you know it is in the car’s electrics, such as a faulty fuse, fuse box connector, earth. Etc.

Try it let me know. Peter

p.s. I always attach a separate earth lead to the back of the head unit chassis as well as the one in the harness connector.