Diagnostic Aids

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

• ECA
• Throttle plate linkage

1) Check For Codes 23, 53, 63, 121, 122 Or 123  If vehicle is equipped with a speed control, speed control servo must be electrically disconnected. This prevents speed control system from affecting throttle plate movement during Output State Check. Rerun QUICK TEST or Output State Check.

Turn ignition off and wait 10 seconds. Perform KOEO SELF-TEST. If Codes 23, 53, 63, 121, 122 or 123 are displayed, go to appropriate KOEO SELF-TEST CODES chart under SERVICE CODE REFERENCE CHARTS and service code(s) as necessary. If no code is displayed, go to TEST QA, step 1). If Code 11/111 (pass code) is displayed, go to next step.

2) Check Throttle Linkage  Check throttle and linkage for sticking or binding. If throttle and linkage are okay, replace TPS and repeat QUICK TEST. If throttle and linkage are binding, repair as necessary and repeat QUICK TEST.