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ELECTRONIC SELF-DIAGNOSTICS Buick Century V

Diagnosis - 4t60-e 1 illustration ~371 words

ELECTRONIC SELF-DIAGNOSTICS

Note. To test electronic control of transaxle solenoids without using self-diagnostics or if self-diagnostics will not work, go to appropriate COMPONENT TESTS under ELECTRONIC TESTING . After repairs are made, trouble codes should be erased from computer memory. See CLEARING TROUBLE CODES under ELECTRONIC SELF-DIAGNOSIS.

Scheme 109

Scheme 109: RETRIEVING CODES (WITHOUT SCAN TOOL)
Scheme 109: RETRIEVING CODES (WITHOUT SCAN TOOL)
  1. Turn ignition on. DO NOT start engine. CHECK ENGINE or SERVICE ENGINE SOON light should glow. Locate Assembly Line Data Link (ALDL) connector attached to control module wiring harness. Most ALDL connectors are located under dash on driver's side of vehicle. Turn ignition on with engine not running. Insert jumper wire from terminal "B" (diagnostic test terminal) to terminal "A" (ground) of ALDL connector. (Scheme 109) NOTE: Inserting jumper wire into test and ground terminals of ALDL connector with engine running will cause fuel injected vehicles to enter field service mode. The CHECK ENGINE or SERVICE ENGINE SOON light will not indicate codes if this is done. NOTE: Code 12 should always exist when ALDL is grounded with key on and engine not running.
  2. CHECK ENGINE or SERVICE ENGINE SOON light should begin to flash codes. Each code will be repeated 3 times. For example, FLASH, FLASH, pause, FLASH, longer pause, identifies Code 21. The first series of flashes is the first digit of trouble code. The second series of flashes is the second digit of trouble code.
  3. Trouble codes are displayed starting with lowest numbered code. Each code is displayed 3 times. Codes will continue to repeat as long as ALDL test terminal is grounded.
  4. If codes are not flashed, or CHECK ENGINE or SERVICE ENGINE SOON light does not glow, self-diagnostics will not work. See DIAGNOSTIC CIRCUIT CHECK in BASIC TESTING article in the ENGINE PERFORMANCE section. To exit diagnostic mode, turn ignition off and remove jumper wire from ALDL connector.

Note. Trouble codes will be recorded at various operating times. Some codes require operation of affected sensor or switch for 5 seconds; others may require operation for 5 minutes or longer at normal operating temperature, road speed and load. Therefore, some codes may not set in a service bay operational mode and may require road testing vehicle in order to duplicate condition under which code will set.