Inspection Procedure 3

INSPECTION PROCEDURE 3: The Malfunction Indicator Lamp (SERVICE ENGINE SOON or Check Engine Lamp) Remains Illuminated and Never Goes Out.

COMMENT

- In cases such as the above, the cause is probably that the ECM [M/T] or the PCM [A/T] is detecting a problem in a sensor or actuator, or that one of the malfunctions listed at next has probably occurred.

TROUBLESHOOTING HINTS (The most likely causes for this case:)

- Shorted the malfunction indicator lamp (SERVICE ENGINE SOON or Check Engine Lamp) circuit.

DIAGNOSIS

Required Special Tools:

- Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A

STEP 1. Using scan tool MB991958, read the diagnostic trouble code (DTC).





CAUTION:
To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK"
(OFF) position before connecting or disconnecting scan tool MB991958.

(1)Connect scan tool MB991958 to the data link connector.
(2)Turn the ignition switch to the "ON" position.
(3)Read the DTC.
(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is DTC set?

YES Refer to Diagnostic Trouble Code Chart Multiport Fuel Injection (MFI).

NO Go to Step. 2.

STEP 2. Check the trouble symptoms.

(1)Turn the ignition switch to the "ON" position.

- The malfunction indicator lamp (SERVICE ENGINE SOON or Check Engine Lamp) should go out when 20 seconds have passed after the ignition switch was turned to the "ON" position.

(2)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Does the malfunction indicator lamp (SERVICE ENGINE SOON or Check Engine Lamp) go out?

YES It can be assumed that this malfunction is intermittent. How to Cope With Intermittent Malfunctions.
NO Replace the combination meter.