No Dash Lights After Aftermarket Stereo Install - Blown Dimmer Rheostat

Electricalintermediate✓ OP Confirmed

Problem

After installing an aftermarket head unit without disconnecting the battery and without properly connecting the illumination/dimmer wires on the radio wiring harness adapter, all dash lights and climate control lights stopped working when headlights or running lights were switched on.

Dash lights do not illuminate when headlights are turned onClimate control LEDs and digital temp gauge turn off when headlights are switched onAll lights flash on for a split second then stay off when headlight switch is engagedClimate control display works normally with headlights offDimmer switch has no effect when rotatedBurnt/acrid smell from dimmer switch area

Root Cause

The aftermarket radio wiring harness adapter has two wires for the dimmer circuit (orange with white stripe for illumination power, and a dimmer ground) that were left unconnected during the stereo install. With the battery connected during installation, this caused a short circuit — an overflow of current with no path to follow. The dimmer switch (Light Control Rheostat) is designed to blow like a fuse to protect the gauge cluster circuit board, and it burned out, breaking the dash light circuit.

Confidence

High confidence — Original poster confirmed this resolved the issue

View Original Thread →Posted January 2008 on SupraForums.com