DTC B1312[15] Steering Switch Input Circuit Short to Battery or Open (BCM)

1. Body control system check

Refer to "64.Body Control 10I.Troubleshooting(BCM) diagnostic system check-body controls".

2. Current DTC check

1) Connect the scan tool.

2) Turn OFF the ignition switch.

3) Turn ON the ignition switch.

4) Observe the DTC information with a scan tool. Is a DTC set?

Yes

=>Go to Cruise control switch inspection.

No

Go to Intermittent conditions of body control system.

Refer to "223.Body Control 36D.Symptom(BCM) intermittent conditions of body control system".

3. Cruise control switch inspection

1) Turn OFF the ignition switch.

2) Remove the cruise control switch.

Refer to "9.Body, Cab, Accessories 9C.Electrical Control, Entertainment cruise control steering wheel switch removal".

3) Perform the cruise control switch inspection.

Refer to "9.Body, Cab, Accessories 9C.Electrical Control, Entertainment cruise control steering wheel switch inspection".

4) Is the result normal?

Yes

=>Go to Cruise control switch input circuit inspection.

No

Replace the cruise control switch.

Refer to "9.Body, Cab, Accessories 9C.Electrical Control, Entertainment cruise control steering wheel switch removal".

Refer to "9.Body, Cab, Accessories 9C.Electrical Control, Entertainment cruise control steering wheel switch installation".

=>Go to Repair verification.

4. Cruise control switch input circuit inspection

1) Disconnect the cruise control switch harness connector (B34).

2) Disconnect the BCM harness connector (B16).

3) Inspect the cruise control switch input circuit between the BCM (pins 2 and 20 of B16) and the cruise control switch (pins 1 and 11 of B34) for the following. Is the result normal?

Refer to "LHD Body Control" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Body Control (4JJ3 with DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Body Control (4JJ3 without DPD, RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to Inspection for open circuit in cruise control switch ground circuit.

No

Repair the circuit as necessary.

=>Go to Repair verification.

5. Inspection for open circuit in cruise control switch ground circuit

1) Inspect the ground circuit between the BCM (pin 19 of B16) and the cruise control switch (pin 12 of B34) for an open circuit or high resistance. Is the result normal?

Refer to "LHD Body Control" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Body Control (4JJ3 with DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Body Control (4JJ3 without DPD, RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to BCM harness connector inspection.

No

Repair the circuit as necessary.

=>Go to Repair verification.

6. BCM harness connector inspection

1) Inspect for poor connections at the BCM harness connector (pins 2, 19, and 20 of B16). Is the connection status normal?

Refer to "LHD Body Control" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Body Control (4JJ3 with DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Body Control (4JJ3 without DPD, RZ4E)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to BCM replacement.

No

Repair the connections as necessary.

=>Go to Repair verification.

7. BCM replacement

Refer to "9.Body, Cab, Accessories 9Z.Body, Cab, Accessories Electrical Control BCM removal".

Refer to "9.Body, Cab, Accessories 9Z.Body, Cab, Accessories Electrical Control BCM installation".

Refer to "9.Body, Cab, Accessories 9Z.Body, Cab, Accessories Electrical Control BCM setting".

Procedure completion

=>Go to Repair verification.

8. Repair verification

1) Clear the DTC with a scan tool.

2) Turn OFF the ignition switch for 30 seconds or more.

3) Turn ON the ignition switch.

4) Observe the DTC information with a scan tool.