Shift Solenoid - Single

Remove the transmission oil pan to access and replace a single shift solenoid in the A-518 (46RH/46RE) automatic transmission. Requires fluid drain, pan removal, electrical connector service, and refill.

Warnings

Tools required

Parts

• Shift solenoid (governor pressure solenoid or overdrive solenoid) × 1 — Use OEM specification - verify which solenoid requires replacement
• Transmission oil pan gasket × 1 — Use OEM specification
• Transmission filter (optional but recommended) × 1 — Use OEM specification

Fluids

• ATF+3 or ATF+4 automatic transmission fluid — 5 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow transmission to cool if recently operated
3. Raise vehicle using floor jack and support securely on jack stands at frame rails
4. Verify sufficient clearance to work under vehicle comfortably

Procedure

1. 1

   Locate transmission pan and identify solenoid access
   From under the vehicle, locate the transmission oil pan on the underside of the A-518 transmission (behind the engine, mid-vehicle). The shift solenoids are mounted on the valve body inside the pan. Identify which solenoid requires replacement: the governor pressure solenoid is typically located on the driver side of the valve body, while the overdrive solenoid is on the passenger side.
2. 2

   Drain transmission fluid
   Position a large drain pan under the transmission oil pan. The A-518 does not have a drain plug, so fluid must be drained by loosening the pan bolts. Begin by loosening all pan bolts approximately 2-3 turns, starting with the rear bolts first. Carefully loosen one corner of the pan (rear corner is preferred) to allow fluid to drain in a controlled manner. Allow fluid to drain completely, which will take several minutes. Once drained, remove all pan bolts completely.
3. 3

   Remove transmission oil pan
   With all bolts removed, carefully lower the transmission pan. The pan may stick to the gasket; use a flat-blade screwdriver to gently break the seal if necessary, taking care not to damage the pan or transmission case mating surface. Remove the pan completely and set aside. Some residual fluid will remain in the pan.
4. 4

   Remove transmission filter (if replacing)
   If replacing the filter while the pan is removed, locate the filter attached to the valve body with 3 bolts. Remove these bolts and pull the filter straight down and away from the valve body. Discard the old filter and O-ring.
5. 5

   Identify and disconnect target solenoid
   Locate the solenoid to be replaced on the valve body. The governor pressure solenoid is a single-wire unit on the driver side; the overdrive solenoid is a two-wire unit on the passenger side. Disconnect the electrical connector by depressing the locking tab and pulling the connector straight off the solenoid. Note the routing of the wiring harness for reinstallation.
6. 6

   Remove failed solenoid
   Remove the solenoid mounting bolt (typically a single bolt with integrated clamp bracket). Carefully pull the solenoid straight out of the valve body bore. Some solenoids may have an O-ring seal that remains in the bore; remove and discard if present. Inspect the valve body bore for debris or damage.
7. 7

   Install new solenoid
   Lubricate the new solenoid O-ring with clean transmission fluid. Insert the new solenoid into the valve body bore, ensuring proper alignment. The solenoid should seat fully into the bore. Install the mounting bolt and clamp bracket, torquing to specification. Reconnect the electrical connector, ensuring it locks securely into place.
8. 8

   Install new filter (if removed)
   If the filter was removed, install the new filter with a new O-ring. Align the filter with the valve body pickup, push up firmly to seat the O-ring, and install the 3 mounting bolts. Torque bolts to specification.
9. 9

   Clean pan and mating surfaces
   Thoroughly clean the transmission oil pan, removing all old gasket material and debris. Use a plastic scraper on the pan mating surface and the transmission case mating surface. Wipe both surfaces clean with shop towels and brake cleaner. Inspect the pan for cracks or damage, paying particular attention to the bolt holes and pan rails. Clean the magnet in the pan to remove accumulated debris.
10. 10

    Install new gasket and reinstall pan
    Position the new pan gasket on the transmission case, aligning all bolt holes. Some gaskets are cork or rubber and may benefit from a thin film of gasket sealant to hold them in place during installation (check gasket manufacturer instructions). Carefully lift the clean pan into position, aligning with the gasket and bolt holes. Install all pan bolts finger-tight first, then torque in a criss-cross pattern starting from the center and working outward.
11. 11

    Refill transmission fluid
    Lower the vehicle to the ground. Locate the transmission dipstick (passenger side of engine bay). Add approximately 4-5 quarts of ATF+3 or ATF+4 through the dipstick tube using a funnel. Start the engine and allow it to idle. With the parking brake engaged, shift through all gear positions (P-R-N-D-2-1) pausing 2-3 seconds in each position, then return to Park. Check the fluid level with the engine running and transmission in Park. Add fluid as needed to bring the level to the 'Cold' or lower mark on the dipstick. The fluid level will need to be rechecked once the transmission reaches operating temperature.
12. 12

    Final fluid level check
    Drive the vehicle for 10-15 minutes to bring the transmission to operating temperature (160-200°F). Park on level ground with the engine running and transmission in Park. Check the fluid level on the dipstick; it should be in the 'Hot' range crosshatch area. Add fluid if necessary in small increments (1/2 quart at a time). Do not overfill. Inspect under the vehicle for any leaks at the pan gasket.

Reassembly

1. Reassembly is covered in the procedure steps above
2. Ensure all electrical connections are secure and properly routed
3. Verify pan bolts are torqued in proper sequence to prevent gasket leaks
4. Allow vehicle to idle for 5 minutes after refill before test driving to circulate fluid through valve body

Verification

• Check for transmission fluid leaks at the pan gasket with engine running
• Verify smooth shifting through all gear ranges with no slipping or harsh engagement
• Confirm transmission fluid level is correct at operating temperature
• Test drive vehicle and verify the specific shift complaint that prompted solenoid replacement has been resolved
• Monitor for diagnostic trouble codes related to solenoid function if vehicle is equipped with OBD-I diagnostics

Related trouble codes on this vehicle

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