Service Engine Soon Light is On
The illumination of the Service Engine Soon light indicates that there is a malfunction in the solenoid, control module, or wiring. Check solenoid and module connectors for proper connection.
- Disconnect Air Temperature Switch and install a jumper wire across the terminals.
- With Ignition on disconnect each solenoid connector and with a test light, check for a light from the pink/black wire to ground. If light does not illuminate, check for an open in circuit 39 to the solenoid. If light illuminates, check for a light across terminals. Circuit is OK if there is a light. Check solenoid coil resistance and if less than 20 ohms, replace solenoid and valve. If there is no light, check for an open in circuit 900 to the Air Temperature Switch, an open in circuit in 436 or faulty Control Module.
- Connect solenoid connectors and disconnect both connectors at Control Module. Check for a light between terminals "A" & "B" of the 5 pin connector. If the test light does not illuminate, check for an open circuit to the module. If the test light illuminates, check for a light between 5 pin connector harness terminals "A" & "D". If the test light illuminates, check for a short to ground in circuit 419. If the test light does not illuminate, check for an open in circuit 900 between the solenoid terminal "B" and the module 2 pin connector terminal "A". If circuit 900 is not open, replace the Control Module.
Scheme 68
The illumination of the Service Engine Soon light indicates that there is a malfunction in the solenoid, control module, control relay or wiring. Before diagnosis, check the solenoid and module connectors for proper connection.
- This step is to determine if there is power to the Air Temperature Switch.
- This step will insure that there is power to the circuit by eliminating the Air Temperature Switch. This step will also check the wiring between the Air Temperature Switch and the solenoids.
- This step will check the wiring between the solenoids and ground including the circuit inside the Control Module.
- This step will determine if the problem is a short to ground in the "Service Engine Soon" light circuit or a malfunction in the Air Management System.
- This step checks for Bat(+) at "A" and a ground at "B", to power up the Control Module.
- This step will determine if a ground signal is sent to the relay because CKT 919 is grounded outside the module.
- This step checks for a Tach signal to the Control Module.
