Diagnostic Aids

Perform this circuit test when directed by other CIRCUIT TESTS (TESTS).

This test is only intended to diagnose:

Test conditions.
Throttle plate linkage.

CAUTION: Before disconnecting ECA connector, turn ignition off and wait at least 10 seconds. Before running QUICK TEST, reconnect all components.

NOTE: Unless specified otherwise, disconnect breakout box and reconnect all components after repairs.

1) Check For Codes 23, 53, 63, 121, 122 Or 123 - If vehicle is equipped with cruise control, disconnect cruise control servo electrical connector. This prevents cruise control system from affecting throttle plate movement during OUTPUT STATE CHECK. Rerun QUICK TEST or OUTPUT STATE CHECK. On all models, turn ignition off and wait 10 seconds. Perform KOEO SELF-TEST. If Code 23, 53, 63, 121, 122 or 123 is displayed, go to KOEO SELF-TEST CODE REFERENCE table under KOEO SELF-TEST. Service codes as necessary. If no codes are displayed, go to TEST QA . If Code 11 or 111 (pass code) is displayed, go to next step.

2) Check Throttle Linkage - Check throttle and linkage for sticking and binding. Repair as necessary. Rerun QUICK TEST . If throttle and linkage are okay, replace TPS. Rerun QUICK TEST .