Diagnostic Aids
DO NOT enter this test sequence until a Code 11 or 111 (pass code) has been retrieved in KOEO SELF-TEST. If system has not passed KOEO SELF-TEST, codes recorded in KOER SELF-TEST may not be valid.
Deactivate self-test by removing and reconnecting jumper wire or by procedure specified by test equipment in use. Start and operate engine for 2 minutes at 2000 RPM to warm Heated Exhaust Gas Oxygen (HEGO) sensor. Turn engine off, and wait 10 seconds. Activate KOER SELF-TEST using a jumper wire or appropriate procedure for test equipment used. Start engine. Record all service codes displayed. Check following items:
- If engine starts and stalls (or stalls during self-test), go to CIRCUIT TEST S. See TESTS W/CODES - EEC-IV article in ENGINE PERFORMANCE section.
- If Code 98 or 998 is displayed, EEC-IV system is operating in Failure Management Effects Mode (FMEM) and vehicle has not passed KOEO SELF-TEST. Vehicle cannot be diagnosed while in FMEM mode. See Code 98 or 998 in SERVICE CODE REFERENCE CHARTS of TESTS W/CODES - EEC-IV article in ENGINE PERFORMANCEn.
- If vehicle is equipped with a Brake On-Off (BOO) switch, brake pedal must be depressed and released after ID code portion of test.
- On vehicles with Power Steering Pressure Switch (PSPS), turn steering wheel at least 1/2 turn and release within 1-2 seconds after ID code portion of test.
- If dynamic response code appears, perform a brief Wide Open Throttle (WOT). DO NOT perform WOT unless requested.
- If Code 11 or 111 (pass code) is retrieved during KOER SELF-TEST, service continuous memory codes retrieved in KOEO SELF-TEST. See TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section.
- If Code 11 or 111 (pass code) is retrieved during continuous memory code portion of KOEO SELF-TEST (Code 11-1-11 or Code 111-1-111) and no driveability problem exists, EEC-IV testing is complete. If driveability problems are still present, go to TROUBLE SHOOTING in TRANSMISSION OVERHAUL article.
- If KOER codes are present, see SERVICE CODE REFERENCE. If system will not output codes, go to CIRCUIT TEST QA in TESTS W/CODES - EEC-IV article in the ENGINE PERFORMANCE section.