C1121

DTC C1121 / C1123 / C1124: Vehicle Speed Signal Circuit Failure

DTC C1121: No Vehicle Speed Signal (60 Seconds or More)

DTC C1123: No Vehicle Speed Signal (30 Seconds or More)

DTC C1124: Vehicle Speed Performance (Impossible Deceleration)

Wiring Diagram










DTC Detecting Condition and Trouble Area






DTC Troubleshooting



1.
Was "EPS System Check" performed?
YES
Go to Step 2.
NO
Go to EPS System Check:Electric Type.

2. DTC check

Check ABS/ESP(R) control module and BCM for DTC referring to DTC Check DTC Check
(ABS) or DTC Check DTC Check
(ESP(R)), and DTC Check DTC Check.

Is there any DTC(s) detected?
YES
Go to applicable DTC troubleshooting.
NO
Go to Step 3.

3. DTC check

Check ECM for DTC referring to DTC Check DTC Check.

Is there any DTC(s) detected?
YES
Go to applicable DTC troubleshooting.
NO
Go to Step 4.

4. Vehicle speed signal circuit check

With ignition switch turned OFF, disconnect connectors from BCM.
Check BCM connector for proper connection.
If OK, turn ON ignition switch, measure voltage between "G04-22" wire terminal of BCM connector and body ground.

Is voltage 4 - 5 V?
YES
Go to Step 5.
NO
Go to Step 6.

5. BCM voltage check

With ignition switch turned OFF, connect BCM connector.
Check BCM for vehicle speed signal output referring to Inspection of P/S Control Module and Its Circuits Inspection of P/S Control Module and Its Circuits:Electric Type.

Is it in good condition?
YES
Replace P/S control module.
NO
Replace BCM.

6. Vehicle speed signal circuit check

Check that vehicle speed signal circuit is as follows.
- Insulation resistance of wire harness is infinity between "Vehicle speed signal" terminal and other terminal at P/S control module connector.
- Wiring harness resistance of "Vehicle speed signal" circuit is less than 1ohms.
- Insulation resistance between "Vehicle speed signal" circuit and vehicle body ground is infinity.
- Circuit voltage between "Vehicle speed signal" circuit and ground circuit is 0 - 1 V with ignition switch turned ON.

Is it in good condition?
YES
Replace P/S control module.
NO
Repair or replace defective circuit.