Ok got a 98 Grand cherokee Laraedo that has the fairly common (from my search) problem of interior lights flashing however, mine is one single interior light (The rear hatch light) It also flashes in a discerable pattern (11 times it flashes twice then flashes 3 times, flashes once then repeats) this is not at normal brightness (more like 10%) and my lower console flashes at weird intervals. To further exasperate this when you open the rear passenger doors there is a clicking sound that is fairly loud located behind the lower console. When you close the doors (either one) the sound stops. Rough roads do nothing to change this in any manner that I can tell and this all started on a very humid rainy day if that helps.

 

Your fault symptoms suggest an electrical fault, possibly brought on by moisture getting to the vehicle’s electrics. My advice would be to locate the vehicle’s ECU and gently warm it with a hairdryer or heat gun to drive out any moisture.

The circuit tracks on printed circuit board are separated by such small distances that any contamination can cause problems such as this. If you are confident in removing the ECU, and it will go back with no issues – I would take it out and place it in a warm oven (at 50ºC/120ºF) for a few hours.

Should this cure the fault – it is possible that the location of the ECU makes it prone to moisture and you might like to look at ways of protecting it from moisture/damp to avoid such problems.