Chart 5 Service Engine Soon MIL On, No PCM Codes Set

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. See DTC List, '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. See DTC List, 'PCM DIAGNOSTIC CODES' for those codes that do NOT turn 'ON' the 'SERVICE ENGINE SOON' MIL

Notes on Fault Tree

1. At key 'ON', the 'SERVICE ENGINE SOON' MIL should be 'OFF'. Checking if fault is present.
2. Checking for a code which may have turned 'ON' the MIL.
3, If the 'SERVICE ENGINE SOON' MIL goes 'OFF' when PCM connector '3E/3F' is disconnected, replace the PCM. If the MIL stays 'ON', repair CKT 419 for a short to ground.