1. Check the Fuses:
* Locate the fuse box: Your E150 will have an under-hood fuse box and possibly an interior fuse box (often under the dash). Consult your owner's manual to find the correct fuse box diagrams.
* Identify the power mirror fuse: The manual should indicate which fuse(s) control the power mirrors. Check for a blown fuse (a broken filament). Replace it with a fuse of the same rating.
* Test the mirror: After replacing the fuse, attempt to operate the mirror again. If it works, the problem was a blown fuse.
2. Inspect the Wiring:
* Access the wiring: This is often the most challenging part. You might need to remove interior door panels (requires some disassembly – refer to a repair manual) to access the wiring harness leading to the mirror motor.
* Visual Inspection: Carefully check the wiring harness for any visible damage (broken wires, frayed insulation, corrosion). Look particularly closely at the areas where the wires enter and exit the door, as these are vulnerable points.
* Continuity Test (Advanced): If you have a multimeter, you can test the continuity of the wires. This requires understanding basic electrical testing. The goal is to ensure a complete electrical path from the switch to the motor.
3. Test the Switch:
* Check for continuity: If you have a multimeter, you can test the power mirror switch to see if it is sending a signal. Disconnect the switch and check its connections with the multimeter in continuity mode. A repair manual can show you which terminals should be connected when the switch is activated.
* Switch Replacement: If the switch is faulty, it likely needs to be replaced. These are relatively inexpensive and can usually be purchased from auto parts stores or online retailers (using the correct year, make, and model number).
4. Check the Motor:
* Access the mirror motor: This likely requires removing the door panel.
* Visual Inspection: Look for any obvious damage to the motor.
* Test the Motor (Advanced): You can attempt to directly apply power to the mirror motor terminals (using a battery and jumper wires – exercise extreme caution to avoid short circuits). If the motor works, the problem lies elsewhere in the circuit. If it doesn't, the motor is likely faulty and needs replacing.
5. Ground Connection:
* Check for a good ground: Poor grounding can prevent the circuit from functioning properly. Make sure the mirror assembly and its wiring harness have a good connection to the vehicle's ground.
Important Considerations:
* Repair Manual: A repair manual specific to your 1994 Ford E150 is highly recommended. It will provide detailed diagrams, instructions, and torque specifications to aid in disassembly and reassembly.
* Safety: Disconnecting the battery's negative terminal before starting any electrical work is crucial to prevent accidental short circuits.
* Complexity: If you're not comfortable working with automotive electrical systems, it's best to take your vehicle to a qualified mechanic. Improper repairs can lead to further damage.
Repairing the mirror may involve several steps and possibly purchasing replacement parts. Starting with the simplest checks (fuses, visual inspection) and progressing to more advanced troubleshooting (multimeter tests) is the best approach. Remember safety first!
