Reading and Clearing Diagnostic Trouble Codes

The accessory socket does not work.

CAUTION:
Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.














OPERATION

When the ignition switch is in the ON or ACC position, the accessory socket can be used.
NOTE:
The maximum load of accessory socket is 120 W.

TECHNICAL DESCRIPTION (COMMENT)

If the accessory socket cannot be used even when the ignition switch is in the ON or ACC position, ETACS-ECU, accessory socket itself, or accessory socket power supply circuit may have a problem.

TROUBLESHOOTING HINTS

- Malfunctions of accessory socket
- Malfunction of the ETACS-ECU
- Damaged harness wires and connectors

DIAGNOSIS

Required Special Tools:

- MB992006: Extra fine probe
- MB991223: Harness set
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicles Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

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





(1)
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.

Connect scan tool MB991958. Refer to "How to connect scan too (M.U.T.-III) Reading and Clearing Diagnostic Trouble Codes."
(2)Turn the ignition switch to the "ON" position.
(3)Check whether the ETACS-ECU related DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the DTC set?

YES Diagnose the ETACS-ECU. Refer to Electronic Time and Alarm Control System (ETACS).

NO Go to Step 2.

STEP 2. Using scan tool MB991958, check data list.

Check the input signal of ACC relay. (ETACS-ECU)

- Turn the ignition switch to the ACC position.





Q. Does scan tool MB991958 display the item "ACC switch" as normal condition?

YES Go to Step 3.
NO Troubleshoot the ETACS-ECU. Refer to ETACS - Input Signal Procedure 1
"The ignition switch (ACC) signal is not sent to the ETACS-ECU" Inspection Procedure 1.
STEP 3. Check ETACS-ECU connector C-315, accessory socket connector C-25 for loose, corroded or damaged terminals, or terminals pushed back in the connector

Q. Is ETACS-ECU connector C-315, accessory socket connector C-25 in good condition?

YES Go to Step 4.
NO Repair or replace the damaged component(s) Harness Connector Inspection).
STEP 4. Check the power supply circuit to the accessory socket. Measure the voltage at accessory socket connector C-25.

(1)Disconnect the connector, and measure at the wiring harness-side connector.

(2)Turn the ignition switch to the "ACC" or "ON" position.

(3)Measure the voltage between accessory socket connector C-25 terminal No.2 and ground.

- The voltage should measure approximately 12 volts (battery positive voltage).

Q. Is the measured voltage approximately 12 volts (battery positive voltage)?

YES : Go to Step 7.
NO : Go to Step 5.
STEP 5. Check the wiring harness between accessory socket connector C-25 terminal No.2 and ETACS-ECU connector C-315 terminal No.3.

- Check the power supply lines (battery power supply) for open circuit and short circuit.

Q. Is the wiring harness between accessory socket connector C-25 terminal No.2 and ETACS-ECU connector C-315 terminal No.3 in good condition?

YES Go to Step 6.
NO Repair the wiring harness.
STEP 6. Check the ground circuit to the accessory socket. Measure the resistance at accessory socket connector C-25.

(1)Disconnect the connector, and measure the resistance available at the wiring harness side of the connector.

(2)Measure the resistance value between accessory socket connector C-25 terminal No.1 and ground.

- The resistance should be 2 ohms or less.

Q. Is the measured resistance 2 ohms or less?

YES : Go to Step 8.
NO : Go to Step 7.
STEP 7. Check the wiring harness between accessory socket connector C-25 terminal No.1 and the ground.

- Check the ground wires for open circuit.

Q. Is the wiring harness between accessory socket connector C-25 terminal No.1 and the ground in good condition?

YES Go to Step 8.
NO Repair the wiring harness.
STEP 8. Retest the system

Check if the accessory socket power is turned ON.

Q. Is the check result normal?

YES The trouble can be an intermittent malfunction How to Cope With Intermittent Malfunctions).
NO Replace the accessory socket.