When first pushing down on the brake pedal, the dummy light (for the brake bulb(s)) lights up in the instrument cluster.

As quickly as it appears, it again disappears.

I checked, and replaced-even though both were good, both brake light bulbs, as well as ensuring the third light was in full working order.

I cleaned the contacts (for the bulb holders), as well as replacing fuse #11 (on which the bulbs sit).

I also checked the wiring harness to both holders, as well as the harness to the third light, and they all look to be intact.

Any suggestions would be most appreciated.

Thanks, and I hope that your weekend is most brilliant!

It is cloudy and 31F, a regular heat wave in the Twin Cities!

You will need a helper with good eye sight and no direct sunlight on the rear of the car. As the brake pedal is slowly pushed down, watch the lights turn on. Verify that all 3 come on at the same time, if the 3rd light comes on a fraction later it could be a wiring problem or a ground wire corroding. At the same time make sure the lower lights have the same intensity when they turn on.

I don't know where the little box is located that measures voltage for the brake lights and turns on the idiot light.

I hope it is not a wiring bundle problem at the hatch hinge point. Not relevent to the 1998, but an example of a 2003 XC wiring harness:

http://www.brickboard.com/AWD/volvo/1523732/V70-XC70/tailgate_wire_harness_damage_repair.html

Klaus

Update: All three (brake) lights illuminate at the same time, and the lower (brake) lights have the same intensity (when coming on).

I will continue to investigate, and see what I find.

Thanks, again, Klaus!

Thank you, Klaus, for the suggestions!

I will have a look tomorrow, and report back my findings.

I hope that your evening is most splendid!

p.s. It was a balmy 28C (or about 82F), here in California today! :)

Update: The dealer replaced the Bulb Integrity Relay (# 9442303), and for a few weeks the issue went away.

After a few weeks, the flickering returned-and about a week later, the right (passenger) brake light bulb (which was an Osram OE bulb that the dealer installed when the relay was swapped) failed.

I put in new bulbs (Osram/Slyvania), and again had success for a few weeks-until the flickering began anew.

Any further suggestions would be most appreciated.

Thanks, and I hope that everyone's Sunday is progressing most brilliantly!

Update: Now the left (driver) side bulb (which is an Osram-Sylvania) has burned out-causing the dummy light in the cluster to remain on permanently.

I replaced the bulb, and the dummy light is again off.

Any further ideas as to what could be at the root of this?

Thanks!