Mailbag: 1999 Cadillac Deville Dash Lights Out

[Bruce Nunnally]

Got this as a comment on the blog. Any ideas?

how u doing i have a 1999 cadillac deville and just yesterday my dash lights went out,but the my side lights are on which tells me how cold and hot it is outside,but lights in the middle don't work which tells me how fast im going and how much fuel is in the car,but today it came on and went back out.can u help me

[Cadillac Jim]

The first thing you should look at is the dimmer control on the headlamp switch and the two electric eyes at the center of the dash up near the windshield. If you have the dimmer turned down for night viewing and put papers over the electric eyes on the dash, the car will turn on the headlights and dim the dashboard after about 30 seconds, and in broad daylight it may look like the lights went out.

I'll use the 1997 factory shop manual. There was a platform change in 1998 but I expect that the dash module is the same, or very nearly the same.

The schematic of the power and fuses for the instrument panel cluster is on page 8A-82-0. There are three fuses, one providing power from Retained Accessory Power (20 Amp, CLUSTER), one from Hot in Run and Start (10 Amp, RLY IGN1), and one from Hot in Run and Off (10 Amp, IGN0-BODY). All three fuses are in the trunk compartment fuse block, which is under the trunk liner on the upper left, mounted on the rear of the back seat. The IGN0-BODY fuse powers the PRNDL lights on the dashboard, if you have the floor console shifter. It would be important to know whether or not the electronic PRNDL works when the speedometer goes out.

If all three of those fuses are OK and the electronic PRNDL works, and the headlight dimmer is turned all the way to bright and it still does it, the dash module may have an internal problem. I've never worked that but there are people here who have.

[rockfangd]

A quick and easy try would be to disconnect the battery and see if the problem reoccurs. Its amazing what can be resolved by a reset