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Inspection Procedure 12: ETACS-ECU does not receive any signal from the hood switch.








TECHNICAL DESCRIPTION (COMMENT)


If there is an error to the hood switch input signal, the hood switch signal is no longer output to the communication line.

TROUBLESHOOTING HINTS



DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe

STEP 1. Check hood switch connector A-48 for loose, corroded or damaged terminals, or terminals pushed back in the connector.


Q. Is hood switch connector A-48 in good condition?
Go to Step 2.
Repair or replace the damaged component(s). Refer to GROUP 00E, Harness Connector Inspection . Check that the input signal of hood switch is normal.

STEP 2. Check the hood switch.
Remove the hood switch. Then check continuity between the switch terminals.
Switch position
 Tester connection
 Specified condition
Released
 1 - 2
 Less than 2 ohms
Pressed
 1 - 2
 Open circuit

Q. Is the hood switch in good condition?
Go to Step 3.
Replace the hood switch. Check that the input signal of hood switch is normal.

STEP 3. Check the ground circuit to the hood switch. Test at hood switch connector A-48.
(1)Disconnect hood switch connector A-48 and measure the resistance available at the wiring harness side of the connector.

(2)Measure the resistance value between terminal 1 and ground.

  • The resistance should equal 2 ohms or less.

Q. Is the measured resistance 2 ohms or less?

Go to Step 5.

Go to Step 4.

STEP 4. Check the wiring harness between hood switch connector A-48 (terminal 1) and ground.
Check the ground wires for open circuit.

Q. Is the wiring harness between hood switch connector A-48 (terminal 1) and the ground in good condition?
No action is necessary and testing is complete.
The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. Check that the input signal of hood switch is normal.

STEP 5. Check ETACS-ECU connector C-312 for loose, corroded or damaged terminals, or terminals pushed back in the connector.


Q. Is ETACS-ECU connector C-312 in good condition?
Go to Step 6.
Repair or replace the damaged component(s). Refer to GROUP 00E, Harness Connector Inspection . Check that the input signal of hood switch is normal.

STEP 6. Check the wiring harness between driver’s door switch connector A-48 (terminal 2) and ETACS-ECU connector C-312 (terminal 12).
Check the input lines for open circuit and short circuit.

Q. Is the wiring harness between driver’s door switch connector A-48 (terminal 2) and ETACS-ECU connector C-312 (terminal 12) in good condition?
Replace the ETACS-ECU. Check that the input signal of hood switch is normal.
The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. Check that the input signal of hood switch is normal.