Diagnostic Aids

WARNING: This page is about a different car, the 1993 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

Perform this circuit test when directed by other CIRCUIT TESTS. This test is only intended to diagnose:

Faulty Powertrain Control Module (PCM).
Throttle plate linkage.

1) Check For Codes 121, 122 & 123 Disconnect cruise control servo wiring harness connector (if equipped). Perform KOEO SELF-TEST. If Code 121, 122 or 123 is present, go to appropriate CIRCUIT TEST. See SERVICE CODE-TO-TEST MENUS, and service codes as necessary. If Code 111 (pass code) is displayed, go to step 2). If no code is displayed, go to CIRCUIT TEST QA.

2) Check Throttle Linkage Check throttle and linkage for sticking and binding. If throttle and linkage are okay, replace Throttle Position (TP) sensor and repeat QUICK TEST. If throttle and linkage are binding, repair as necessary and repeat QUICK TEST.