Repair Guide - 1991 Subaru Legacy Transmission Shift Solenoid Replacement

Repair Guide: 1991 Subaru Legacy Transmission Shift Solenoid Replacement

A less typical yet critical problem on a 1991 Subaru Legacy is a faulty transmission shift solenoid. This can adversely affect the automatic transmission shifting. This guide will help you diagnose and replace the solenoid with minimal fuss. Please follow each step carefully and ensure you have all the necessary tools beforehand.

Diagnosis

Note any unusual shifting pattern: Late, early, or skipping gears could indicate a solenoid issue.
Use an OBD-II scanner to check for transmission codes. Common ones for the solenoid include P0750 and P0755.

Tools Required

OBD-II scanner
Socket set
Screwdriver set
Drain pan
Transmission fluid
Replacement solenoid

Replacement Procedure

Disconnect the battery. This minimizes risk of electrical damage or injury.
Place the drain pan under the transmission pan. Remove the pan by unbolting it with the socket set. Note: The fluid may spill out at this step.
Once the pan is removed, you will see the solenoids. They're typically towards the front & side of the transmission.
Disconnect the wiring harness from the solenoid. Be careful, the connector may be brittle from heat.
Remove the solenoid by removing the bolt with a socket or screwdriver.
Install the new solenoid. It should click firmly into place.
Reconnect the wiring harness.
Reinstall the transmission pan and bolt it back into place.
Refill the transmission with the appropriate fluid. Check the level using the dipstick, ensuring it falls within the correct marks.

Tips & Pitfalls

Be careful not to introduce any dirt into the transmission. Any contaminants can cause serious malfunctions.
If the problem persists after replacing the solenoid, you may have an issue with the Transmission Control Module (TCM).
Always dispose of used transmission fluid responsibly. Local waste facilities usually have a disposal service.

Conclusion

Although a bit more complex than standard fare, replacing a transmission shift solenoid on a 1991 Subaru Legacy is not out of reach for an experienced DIY mechanic. Always follow proper safety procedures and don't rush - this repair is relatively straightforward with patience and attention to detail.