Any Electrical Experts?

There is a problem with the rear tail lights and reverse lights on my car. The lights were tested and it was determined that they were receiving power, but the ground was bad. After tearing the entire rear of the car apart and finding no damaged wires, loose grounds, or anything to indicate where the problem was occuring we created a new ground (much like the TSB for the outer tails). This completely fixed the problem, for 48 hours.



Then the right rear inner tail light malfunction indicator came on. I checked and sure enough the bulb was out. The bulb looked fine so I swapped them. The same problem persisted, so we have ruled out a bulb problem. That was several weeks ago and the light on the dash has been on since.



Then something very interesting happened today. I took my car to the automatic car wash, then drove for about 5 minutes and the light went off. I pulled over, put the lights on and sure enough the bulb was now working. After about 15 more minutes of driving the light came back on and the bulb is not working again. Any idea why a car wash might temporarily resolve the problem? And would you suspect a wiring problem in a specific area given the series of events?



I appreciate all the help I can get. Would love to have a nice clean looking gauge cluster again.