Have a 1999 Ram 1500 5.2L 4x4. Recently removed the aftermarket radio to fix a housing problem. returned the OEM sterio to retrieve a cd that was in it. when the aftermarket radio was put back in the dome light, reading lights and sterio had no power to them. All the fuses were checked and appear to be ok. I checked the voltage at the different points of contact ie. the dome light and wiring harness for the radio. there was no voltage at the dome light at all however at the wiring harness for the radio the voltage would spike to 16V when the probe came into contact with the wire and then would very rapidly drop to .52V. I dont understand at all what the problem could be. A little help please?

Thanks,
Ethan

 

I would suspect the "spike" is just your meter acting wierd. Not an impossible scenario but pretty unlikely IMO. What is voltage spiles duration. If less than a second or two and I don't think I'd be trusting my meter t do it well. You probably already know that most handheld multimeters aren't very accurate for time varying signals with any appreciable frequency content to them.

I think what you are seeing is a short to ground and thevoltageaacross wherever the short is. If your meter is accurate enough you could try tracking the shrt location by looking for where the lowest voltage can be read. I'm thinking with voltages like that, something is bound to be getting hot somewhere. That would be another angle. Look for hot/smoking stuff.

 

the spike doesnt last very long at all. maybe a second at the most so you are probably right about the inacurate meter. however as far as the wiring getting hot or smoking i have not been able to trace it. i will continue to look.

Thanks for the help

 

Had this happen to one of mine. Check the IDO fuse in the fuse box in the driverside dash. It has a plastic cover and a normal 10 amp mini blade under it.

 

The interior lights also run through the headlight switch and the "open-door" button in the door jamb. Check those