1. Diagnose the Problem:
* No movement at all: This points to a power issue (fuse, wiring, motor) or a bad switch.
* Intermittent movement: This could be a wiring issue, a faulty motor, or a problem with the switch.
* Movement in one direction only: Likely a problem with the motor or its internal gearing.
* Grinding noise: Definitely a motor or gear problem.
* Mirror only moves slightly then stops: Possible motor issue or blockage.
2. Troubleshooting Steps:
* Check the Fuses: Consult your owner's manual to locate the fuse(s) for the power mirrors. Replace any blown fuses.
* Check the Wiring: Inspect the wiring harness leading to the mirror for any breaks, chafing, or corrosion. This is often found where the wires enter the door. You might need to remove the door panel to do a thorough inspection.
* Test the Switch: Try using the mirror controls on the other side (if it works, it's likely a switch issue). You can also use a multimeter to test if power is reaching the switch when you operate it.
* Test the Motor: With the door panel removed, you can usually access the mirror motor. You might be able to test it directly with a 12V power source (use caution!). If the motor doesn't turn, it needs to be replaced. Caution: Incorrect polarity can damage the motor.
* Check for Obstructions: Something might be jamming the mirror's movement. Look for debris or anything interfering with the mirror's mechanism.
3. Repair/Replacement Options:
* Replace the Fuse: Easiest and cheapest repair.
* Repair Wiring: This may involve soldering or splicing wires. Use waterproof electrical tape to protect the repairs.
* Replace the Switch: This is a moderately difficult repair, requiring removal of the door panel.
* Replace the Motor: This is the most complex repair. It involves removing the door panel, disassembling the mirror assembly, and replacing the motor. You'll likely need to purchase a replacement motor assembly.
* Replace the Entire Mirror Assembly: The easiest but most expensive option. This is especially practical if the mirror housing is damaged.
4. Tools You Might Need:
* Screwdrivers (Phillips and flathead)
* Panel removal tools (to avoid scratching the door panel)
* Multimeter
* Wire strippers/crimpers (if repairing wires)
* Soldering iron (if repairing wires)
* Replacement parts (fuse, switch, motor, mirror assembly)
* 12V power source (for testing motor - use caution!)
Important Notes:
* Disconnect the battery negative terminal before working on the electrical system. This prevents accidental shorts and damage.
* Consult a repair manual: A repair manual specific to your 1999 Jeep Grand Cherokee will provide detailed diagrams and instructions for removing door panels and accessing the mirror components. This will be invaluable.
* If you are uncomfortable working with car electronics, consider taking your Jeep to a qualified mechanic.
Replacing the entire mirror assembly is generally the simplest approach if you lack experience. If you are comfortable with car repairs, you can often find replacement parts relatively inexpensively online (eBay, Amazon, etc.) or at a local auto parts store. Remember to specify the year, make, and model of your Jeep when ordering parts.
