DTC B112A:12 [START STOP UNIT]

id0902p6020500

Description

IG2 relay circuit malfunction
Detection condition
•  Start stop unit detects the IG2 relay output monitor voltage of 2.5 V or more for 0.5 s or more with the ignition switched off or to ACC.
Fail-safe function
•  Door locking operation inhibited while under i-stop control. (With i-stop system)
Possible cause
•  Front body control module (FBCM) connector or terminal malfunction
•  Start stop unit connector or terminal malfunction
•  Short to power supply in wiring harness between start stop unit terminal 2D and front body control module (FBCM) terminal 2U
•  Front body control module (FBCM) malfunction
•  Start stop unit malfunction

Diagnostic Procedure

Step

Inspection

Action
1
INSPECT FRONT BODY CONTROL MODULE (FBCM) CONNECTOR CONDITION
•  Switch the ignition off.
•  Disconnect the negative battery cable.
•  Disconnect the front body control module (FBCM) connector.
•  Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection.
•  Is the connector normal?
Yes
Go to the next step.
No
Repair or replace the connector, then go to Step 5.
2
INSPECT START STOP UNIT CONNECTOR CONDITION
•  Disconnect the start stop unit connector.
•  Inspect the connector engagement and connection condition and inspect the terminals for damage, deformation, corrosion, or disconnection.
•  Is the connector normal?
Yes
Go to the next step.
No
Repair or replace the connector, then go to Step 5.
3
INSPECT FOR SHORT TO POWER SUPPLY IN IG2 RELAY CIRCUIT
•  Always reconnect all disconnected connectors.
•  Reconnect the negative battery cable.
•  Measure the voltage at the front body control module (FBCM) terminal 2U (wiring harness-side).
•  Is the voltage 2.5 V or more?
Yes
Refer to the wiring diagram and verify whether or not there is a common connector between start stop unit terminal 2D and front body control module (FBCM) terminal 2U.
If there is a common connector:
•  Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for a short to power supply.
•  Repair or replace the malfunctioning part.
If there is no common connector:
•  Repair or replace the wiring harness which has a short to power supply.
Go to Step 5.
No
Go to the next step.
4
PERFORM DTC INSPECTION AND VERIFY IG2 RELAY MALFUNCTION
•  Clear the DTC for the start stop unit using the M-MDS.
•  Switch the ignition off and wait for 1 s or more.
•  Retrieve the start stop unit DTCs using the M-MDS.
•  Is the same DTC displayed?
Yes
Replace the front body control module (FBCM), then go to the next step.
(See FRONT BODY CONTROL MODULE (FBCM) REMOVAL/INSTALLATION.)
No
Go to Step 6.
5
VERIFY THAT REPAIRS HAVE BEEN COMPLETED
•  Always reconnect all disconnected connectors.
•  Reconnect the negative battery cable.
•  Clear the DTC for the start stop unit using the M-MDS.
•  Switch the ignition off and wait for 1 s or more.
•  Retrieve the start stop unit DTCs using the M-MDS.
•  Is the same DTC displayed?
Yes
Repeat the inspection from Step 1.
•  If the malfunction recurs, replace the start stop unit.
Go to the next step.
No
Go to the next step.
6
VERIFY IF OTHER DTCs DISPLAYED
•  Are any other DTCs displayed?
Yes
Repair or replace the malfunctioning part according to the applicable DTC troubleshooting.
(See DTC TABLE [START STOP UNIT].)
No
DTC troubleshooting completed.