Installed aftermarket radio, now instrument lights do not work


#1

I recently purchased a 1997 Mitsubishi Mirage from a coworker. Low mileage at 93k miles, in good shape mechanically, and purchased with a complete set of maintenance records. Its radio was not working when I bought it.

I purchased a low-end radio/CD player manufactured by Dual, along with a wiring harness, and installed the radio. I disconnected the negative battery cable to install it, but then reconnected the cable to test the radio.

I had made all the wiring connections and successfully tested the unit while the radio was sitting in the passenger seat. At that time, the dome light was on and I presume the instrument lights (for speedometer, fuel gauge, and temp gauge) were working.

Then, when I pushed the radio unit backwards, along with the assembly of wires, to secure it in the dash. At that time, the dome light went out, and the radio was no longer receiving power. I checked the 10-A fuses for the radio and the dome light (two separate fuses, joined by a plastic clip), and it was severed. I replaced the fuse, and now the dome light and radio are working fine, but the instrument lights are out.

The instrument (gauge) lights are on a separate 10-A fuse, which appears to be in tact.

Can anyone suggest what might be wrong, or how to troubleshoot this issue? I can borrow a multimeter, although I don’t have immediate access to one.


#2

More than once the problem that you have described was found to be the redundant ground wire for the radio was connected to the dash light circuit. Pushing the radio into the dash put the housing in contact with a grounded surface in the dash which made a dead short to ground on the dash light circuit. But I am surprised that the antenna ground didn’t pop it first. Possibly the dash light circuit was rated for a much smaller fuse and the short toasted the dash light dimmer.


#3

When I bought my '88 Escort Pony the dash lights on it were not working. It also had an aftermarket radio installed in it. The problem was that the ground wire for the dash lights had been wired into the positive side of the circuit and was causing it to blow fuses as quick as you could put them in. If there’s nothing on the circuit with the dash lights I would think it should only have a 5 amp fuse.


#4

Thank you to both of you for sharing your experiences.

An update: there was ANOTHER blown fuse that I found. I assume it governs the instrument lights and the vehicle tail lights, which are also out.

In fact, I did have a dilemma about where to connect the ground wire (black) of the radio. There was NO ground wire on the Mitsubishi wiring harness, so when I installed the radio, I connected it to the DASH LIGHT line in the wiring harness. [Cue the Stump-the-Chumps correct answer sound!]

I will rewire this to fix it. Can anyone suggest where to connect the radio’s ground wire?

Its instructions say to attach it to the vehicle ground/chassis, but I don’t see a good place to connect it. I tried connecting it to the metal interior structure using a metal screw, but it didn’t work in that setup.


#5

Wait, there HAS to be a ground wire that ran to the factory radio. Electrical devices don’t run without at least a power lead and a ground.

but, if you can’t find it, run the ground to a solid METAL part of the car, like the firewall or a portion of the floor as it tucks up under the dash, under the carpet.


#6

Thanks for the suggestion. You’re right, BustedKnucles: I DID find another wire in the harness that was at ground, but this one worked better, in that it did not cause problems in any other circuits.

Thanks again!


#7

Looking at some service data for your car it shows the light circuit for the radio isn’t supposed to tie to ground directly. The return side of the lamp ties to the dimmer control and then to ground. The way you have it now will work but the dimmer control for it won’t. There is a grn/wht wire for the power and a blk/yel wire for the return side of the lamp.