- Powertrain/On-Board Diagnostic System Check

Self Diagnostic System Check:

NOTE: For referrals to any chart not included in DIAGNOSTIC CHARTS, refer to COMPUTERIZED ENGINE CONTROLS.



The SELF-DIAGNOSTIC CIRCUIT CHECK is an organized approach for identifying a problem caused by the on-car computer-controlled electronics. Understanding this chart and using it correctly will reduce diagnosis time and prevent the unnecessary replacement of parts. Refer to HOW TO ENTER DIAGNOSTIC MODE.

NOTES ON CHART:

1. This process assures that there are not BCM inputs active that would not allow the system to wake-up in the correct sequence. Are the IPC and Combo panel displays operating? If these displays are not operating, then the problem is related to power and ground circuits to the IPC, Combo panel, or BCM.

2. Is the engine control system fault lamp working? If this lamp fails to illuminate during crank, then the problem could be in the power supply circuits to the computer system.

3. The odometer displays and the engine control system lamp works. Enter diagnostics and continue with code diagnosis. If diagnostics cannot be entered, refer to CHART C-1. Is there a trouble code displayed? If a trouble code is identified using the self Diagnostics, a problem has been detected by the system which can be corrected following the appropriately numbered code chart. Codes with a prefix of "E" are ECM codes, "B" are BCM codes, "L" are Lighting codes, and "R" are SIR codes.


CLEARING TROUBLE CODES


PCM/ECM

To clear PCM/ECM trouble codes enter diagnostics. After the segment check and the codes are displayed, select the PCM/ECM system level by pressing the "HI" button, then press the "LO" button to select the "CLEAR CODES?" test type. When "CLEAR CODES?" is displayed, push the "HI" button and the PCM/ECM codes will be cleared.

BCM

To clear BCM trouble codes enter diagnostics. After the segment check and the codes are displayed, push the "LO" button to select the BCM system level, when "BCM?" is displayed, press the "HI" button, then press the "LO" button to select the "CLEAR CODES?" test type. When "CLEAR CODES?" is displayed then push the "HI" button and the BCM codes will be cleared.

NOTE: If PCM/ECM codes are cleared at any time, snapshot code information will be lost. On-board diagnostics cannot be used to clear SIR code 51, refer to TSB bulletin #91-I-20 12/90.