Inspection
Procedure 1: Check the DC/DC converter power supply circuit.
caution
Even when the diagnosis code
No. B1301 or B1302 is set in the AS&G-ECU, do not conclude as a DC/DC converter or
AS&G-ECU error, and be sure to check the DC/DC converter power supply circuit.
CIRCUIT OPERATION
The power supply to the DC/DC converter is provided by the fusible
link.
The ACC signal is received from ETACS-ECU.
PROBABLE CAUSES
The DC/DC converter (Entertainment) connector may be defective.
The battery may be defective.
Damaged harness wires and connectors
DIAGNOSIS PROCEDURE
STEP 1. Battery test
Check the battery state. (Refer to .)
Q.
Is the check result normal?
Go to Step 2
Replace the battery.
STEP 2. M.U.T.-III ETACS system data list
Check the input signal of ACC relay.
Turn the ignition switch to the ACC position.
Item No.
Item name
Normal condition
Item 288
ACC switch
ON
OK: Normal condition is displayed.
Q.
Is the check result normal?
Go to Step 3
Refer to ETACS - Input Signal Procedure 1 "The ignition switch (ACC)
signal is not sent to the ETACS-ECU" .
STEP 3. Voltage measurement at DC/DC converter (Entertainment)
connector (IGN terminal).
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Turn the ignition switch to the ACC position.
(3)Check the voltage between DC/DC converter (Entertainment) connector (IGN
terminal) and body earth. OK: System voltage
Q.
Is the check result normal?
Go to Step 5
Go to Step 4
STEP 4. Check of short to power supply, short to earth, and open circuit
in IGN line between DC/DC converter (Entertainment) connector and ETACS-ECU connector
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use Troubleshooting/inspection Service Points - How to Cope with Intermittent
Malfunction ).
Repair the connector(s) or wiring harness.
STEP 5. Voltage measurement at DC/DC converter (Entertainment)
connector (PWR terminal).
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Check the voltage between DC/DC converter connector (PWR terminal) and
body earth. OK: System voltage
Q.
Is the check result normal?
Go to Step 7
Go to Step 6
STEP 6. Check of short to power supply, short to earth, and open circuit
in PWR line between fusible link and DC/DC converter (Entertainment) connector
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use Troubleshooting/inspection Service Points - How to Cope with Intermittent
Malfunction ).
Repair the connector(s) or wiring harness.
STEP 7. Resistance measurement at DC/DC converter connector
(GND terminal)
(1)Disconnect the connector, and measure at the wiring harness side.
(2)Check the continuity between the DC/DC converter connector (GND terminal)
and body earth. OK: Continuity exists (2 Ω or less)
Q.
Is the check result normal?
No action is necessary and testing is complete.
Go to Step 8.
STEP 8. Check of open circuit in GND line between DC/DC converter
connector and body earth
Q.
Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How
to use Troubleshooting/inspection Service Points - How to Cope with Intermittent
Malfunction ).
.)
Go to Step 2
Replace the battery.