Inspection Procedure B-1

INSPECTION PROCEDURE B-1: Tone Alarm: Ignition key reminder tone alarm function does network normally.

TECHNICAL DESCRIPTION (COMMENT)
The ETACS-ECU operates the ignition key reminder tone alarm function, based on input signals from the following switches:
- Ignition switch (IG1)
- Key reminder switch Driver's door switch
If the function does not work normally, a defect on the relevant circuit or the ETACS-ECU may be suspected.

TROUBLESHOOTING HINTS
- The key reminder switch may be defective
- The driver's door switch may be defective
- The ETACS-ECU may be defective
- The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector

DIAGNOSIS
Required Special Tools:
- MB991223: Test Harness Set
- MB991502: Scan Tool (MUT-II)
- MB991529: Diagnostic Trouble Code Check Harness

STEP 1. Check the ETACS-ECU power supply circuit.
Check that the hazard warning light illuminates when the ignition switch is in the "LOCK" (OFF) position.

Q: Does the hazard warning light illuminate?

YES : Go to Step 2 or 3 .

NO : Check the ETACS-ECU battery circuit. Refer to Inspection Procedure P-1. Inspection Procedure P-1

STEP 2. Check the input signal (by using scan tool MB991502).
Check the input signals from the following switches:
- Ignition switch (IG1)
- Key reminder switch
- Driver's door switch

CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 to the data link connector.
2. Check that the tone alarm of scan tool MB991502 sounds when the input signal enters.

Q: Does the tone alarm of scan tool MB991502 sound when the input signal enters?

YES : Replace the ETACS-ECU. The ignition key reminder tone alarm function should work normally.

NO:
- Scan tool MB991502 does not sound when the ignition switch is turned from "ACC" to "ON": Refer to Inspection Procedure O-2 "The ignition switch (IG1) signal is not sent to the ETACS-ECU." Inspection Procedure O-2
- Scan tool MB991502 does not sound when the ignition key is inserted and then removed: Refer to Inspection Procedure O-3 "The key reminder switch signal is not sent to the ETACS-ECU." Inspection Procedure O-3
- Scan tool MB991502 does not sound when the driver's door is opened: Refer to Inspection Procedure O-8 "The driver's or passenger's door switch signal is not sent to the ETACS-ECU." Inspection Procedure O-8

STEP 3. Check the input signal (by using a voltmeter).
Check the input signals from the following switches:
- Ignition switch (IG1)
- Key reminder switch
- Driver's door switch

1. Use special tool MB991529 to connect a voltmeter between ground terminal 4 or 5 and ETACS-ECU terminal 9 of the data link connector.
2. Check that the voltmeter indicator deflects once when the input signal enters.

Q: Does the voltmeter indicator deflect?

YES : Replace the ETACS-ECU. The ignition key reminder tone alarm function should work normally.

NO :
- The voltmeter needle does not fluctuate when the ignition switch is turned from "ACC" to "ON": Refer to Inspection Procedure O-2 "The ignition switch (IG1) signal is not sent to the ETACS-ECU." Inspection Procedure O-2
- The voltmeter needle does not fluctuate when the ignition key is inserted and then removed: Refer to Inspection Procedure O-3 "The key reminder switch signal is not sent to the ETACS-ECU." Inspection Procedure O-3
- The voltmeter needle does not fluctuate when the driver's door is opened: Refer to Inspection Procedure O-8 "The driver's or passenger's door switch signal is not sent to the ETACS-ECU." Inspection Procedure O-8