Chart 4 Service Engine Soon MIL Inoperative

Chart 4:

Wiring Diagram:

CIRCUIT DESCRIPTION:
The 'SERVICE ENGINE SOON' MIL is controlled by the PCM through CKT 419 and indicates that the PCM has detected a problem that affects vehicle emissions, may cause powertrain damage or severely impacts driveability.

'SERVICE ENGINE SOON' MIL ON
1. MALFUNCTION: When certain PCM codes are current. Refer to, 'PCM DIAGNOSTIC CODES' for those codes that turn 'ON' the 'SERVICE ENGINE SOON' MIL.

2. DIAGNOSTIC MODE: After the indicator and segment check, the telltale should remain 'ON'.

'SERVICE ENGINE SOON' MIL OFF
1. Key 'ON', engine not running.

2. ENGINE RUNNING: No PCM codes current. The telltale can be off with PCM codes stored. Refer to 'PCM DIAGNOSTIC CODES' for those codes that do NOT turn 'ON' the 'SERVICE ENGINE SOON' MIL.

NOTES ON FAULT TREE:
1. Checking if SES MIL circuitry is OK and the PCM is unable to control output.

2. Checking CKT 419 for an open.

3. Checking for an open in CKT 39 or inside the IPC.