DTC B1053[23] SRS-PWM (Low) Communication Malfunction (eCall unit)

1. Body control system check

Refer to "64.Body Control 10I.Troubleshooting(eCall unit) diagnostic system check - emergency call system controls".

2. Current DTC check

1) Connect the scan tool.

2) Turn ON the ignition switch.

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

Yes

=>Go to SRS control unit DTC check.

No

Go to Intermittent conditions of body control system.

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

3. SRS control unit DTC check

1) Observe the DTC information for SRS control unit with a scan tool. Is a DTC set?

Yes

Go to the applicable DTC diagnosis.

No

=>Go to Airbag deployment signal circuit inspection.

4. Airbag deployment signal circuit inspection

1) Disconnect the following harness connector.

  • eCall unit harness connector (B85)
  • SRS control unit harness connector inspection (R7)

2) Inspect the airbag deployment signal circuit between the eCall unit and the SRS control unit for the following. Is the result normal?

Circuits to inspect

  • Between the eCall unit (pin 14 of B85) and the SRS control unit (pin 19 of R7)

Inspection items

  • Open circuit or high resistance
  • Short to ground

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

Yes

=>Go to eCall unit harness connector inspection.

No

Repair the circuit as necessary.

=>Go to Repair verification.

5. eCall unit harness connector inspection

1) Inspect for poor connections at the eCall unit harness connector (pin 14 of B85). Is the connection status normal?

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

Yes

=>Go to eCall unit replacement.

No

Repair the connections as necessary.

=>Go to Repair verification.

6. eCall unit replacement

Note

  • Perform programming after replacing the eCall unit.

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

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

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

Procedure completion

=>Go to Repair verification.

7. 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.