Symptoms
The rear glass won't go down, so the interior tailgate handle can't be reached. YourMechanic says the tailgate window is 'notorious for failing'.
The fix, step by step
- Test the dash switch and the key switch in the tailgate first; Hagerty says the rear switch often dies.
- If the motor hums but the glass doesn't move, open the tailgate inner panel (lower the glass by hand with the manual crank if you need to) and check the lifter cushions and glass channels for binding.
- Replace worn cushions and channels, lube the tracks, and fit a new switch if needed.
Tools & part numbers
- Trim tools
- test light or multimeter
- sockets
- silicone or lithium lube
Where to buy the parts
Tailgate window dash switch with harness, 1986–1991Team Grand Wagoneer ↗Amazon ↗
Tailgate glass window switch kit, 1974–1991Team Grand Wagoneer ↗Amazon ↗
Tailgate window lifter cushion, 1979–1991Team Grand Wagoneer ↗Amazon ↗
Tailgate glass window channel, 1968–1991Team Grand Wagoneer ↗Amazon ↗
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Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.