AXOD Transaxle Electrical System Diagnosis: Notes

WARNING: This page is about a different car, the 1987 Mercury Lynx, 1987 Ford Escort EXP, and 1987 Ford Escort. However, it is still accessible from the selected car via links, so may be relevant.

This test should be performed ONLY if a problem has been detected in transaxle. If any of these service codes appeared during SELF-TESTS, the TEST RR - AXOD TRANSAXLE should be performed. The following AXOD transaxle related items have malfunctioned or failed as indicated:

Code 39 Displayed. Transaxle converter by-pass clutch is not operating properly.
Code 59 Displayed. THS 4/3 pressure switch circuit has failed open.
Code 62 Displayed. THS 4/3 pressure switch circuit failed closed. If code appears in KEY ON/ENGINE OFF (KOEO) SELF- TEST, THS 3/2 circuit has failed. If code appears in KEY ON/ENGINE RUNNING (KOER) SELF-TEST, THS 4/3 circuit has failed. If code appears in both SELF-TESTS, both circuits have failed and must be checked.
Code 69 Displayed. THS 3/2 circuit has failed open.
Code 89 Displayed. Transaxle converter by-pass clutch solenoid has stayed always open or closed.

The following service codes are not AXOD transaxle related, but can affect converter clutch by-pass operation. Service these components before servicing AXOD transaxle codes:

Code 21 Displayed. Engine Coolant Temperature (ECT) sensor out of range.
Code 22 Displayed. Manifold Absolute Pressure (MAP) sensor out of range.
Code 23 Displayed. Throttle Position Sensor (TPS) out of range.
Code 24 Displayed. Air Charge Temperature (ACT) sensor out of range.
Code 29 Displayed. Vehicle Speed Sensor (VSS) not functioning.
Code 74 Displayed. Brake ON/OFF (BOO) switch always open or brake not applied during KEY ON/ENGINE RUNNING (KOER) SELF- TEST.
Code 75 Displayed. Brake ON/OFF (BOO) switch always closed.

The following service code indicates that a transaxle component may have caused faulty engine idle speed control:

Code 57 Displayed. Neutral Pressure Switch (NPS) failed in Neutral (open). The NPS is normally open and closes with hydraulic pressure. Failure of transaxle to engage in "D" or "R" will cause service code 57 to be displayed. Check for proper hydraulic pressure before testing AXOD transaxle electrical components.

NOTE: Ensure that all components are connected before performing test. Perform TEST RR - AXOD TRANSAXLE on a slight upgrade or flat terrain. If any other non-AXOD related codes appear, service those codes first as they could affect electrical operation of transaxle.