Wish you would go on about , I still love the SJ. Wish I still had my '78. Pic's are welcome !
agree that door deals could be an issue since the jeep is advanced in years for its shape and rubber loses its flex over time. Cowl leaks are a concern but if you've got no water coming through the firewall or kick panels , it's likely to be door gaskets . Always worth a proper inspection.
As for the power door glass issue , it sounds like ratty switches are the cause if they've gotten lots of use over the years. Drivers door switches are most used but since it's a four door and likely had much passenger use , all switches may have had their share of use.
The constant pressing of the rocker switches eventually wears at the spring action of the switch internals like keyboard buttons on a laptop or PC so into inevitable that internal contacts will fail. Since the motors seem to work , the switch is probably the cause.
You would have to ask yourself how much use the door motors have gotten but it may be necessary to check operation of the window motors to be sure it isn't an issue of sloppy motors since gears and and bushing wear . If you can find the correct combination of power to position on the switch connection when the problem occurs , you can check if the motor is failing at that time or if it's the switch. A test light will find the power terminal and verification of wire color code to the motor will tell which is a polarity wire to cause the motor to work in opposite direction to raise and lower the glass. It looks complicated but there should be a power jumper from the master switch from the driver control to each passenger. Usually however it is the front driver to rear passenger and front passenger to rear passenger that follows in suit. The rest is ground and reverse polarity for direction of glass movement.
Pone other thing that should be mentioned before buying any replacement parts is to look for the lubrication that should be on the window regulators . If the factory grease has worn or washed off , reapply a good chassis grease that isn't too heavy in viscosity . Too heavy will make too much strain on the regulator to I've heavy glass and strain the window lift motor. Lithium grease works well and is water resistant but should be reapplied somewhat often so check what a manual would recommend. If your lucky , the only problem is that and the circuit is the only part suffering due to overheating from excess motor strain . That may be why the motors quit and work at no particular intervals. Hope this helps .
