C1101

C1101

Component Location:

General Description
The ABS ECU (Electronic Control Unit) checks the battery voltage to determine, as a safety issue, whether the ABS system can operate normally or not. The normal battery voltage range is essential for controlling the ABS system as intended.

DTC Description
The ABS ECU monitors battery voltage by reading the value of voltage.
When the voltage is higher than the expected normal value, this code is set, and the ABS/EBD functions are prohibited.
If the voltage recovers, to within normal operating ranges, then the controller returns to normal operation as well.

DTC Detecting Condition:

Schematic Diagram:

Monitor Scantool Data
1. Connect scantool to Data Link Connector (DLC)
2. Engine "ON".
3. Monitor the "BATTERY VOLTAGE" parameter on the scantool.

Specification : Approx. 14.5 ± 0.5 V (20 °C)






4. Is parameter displayed within specifications?

YES - Fault is intermittent caused by poor connection in power harness (IGN+) and/or HECU's connector or was repaired and HECU memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.

NO - Go to "W/Harness Inspection" procedure.

Terminal and Connector Inspection
1. Many malfunctions in the electrical system are caused by poor harness (es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?

YES - Repair as necessary and then go to "Verification of Vehicle Repair" procedure.

NO
- Confirm the DTC status at another system to be able to confirm C1101 or DTC code related to over voltage.
- If there isn't C1101 code at another system, Go to "Power Circuit Inspection" procedure.
- If there is C1101 or DTC code related to over voltage at another system, Go to "Alternator Output Voltage Inspection" procedure.

Alternator Output Voltage Inspection
4. Engine "ON".
5. Measure voltage between the battery terminal (+) and the battery terminal (-).

Specification : Approx. 14.5 ± 0.5 V (20 °C)






6. Is the measured voltage within specifications?

YES - Go to "Power Circuit Inspection" procedure.

NO - Check for damaged harness and poor connection between alternator and battery. If OK repair or replace alternator and then go to "Verification of vehicle Repair" procedure.

Power Supply Circuit Inspection
1. Engine "ON".
2. Measure voltage between the battery terminal (+) and terminal "4" of the HECU harness connector.

Specification : Approx. below 0.2 V






3. Is the measured voltage within specifications?

YES - Go to "Ground Circuit Inspection" procedure.

NO - Check for damaged harness and poor connection between the battery terminal (+) and terminal "4" of the HECU harness connector. Repair as necessary and then go to "Verification of vehicle Repair" procedure.

Ground Circuit inspection
1. Ignition "OFF".
2. Disconnect HECU connector.
3. Measure resistance between terminal "8,24" of the HECU harness connector and chassis ground.

Specification : Approx. below 1 ohm






4. Is the measured resistance within specifications?

YES - Go to "Component Inspection" procedure.

NO - Check for damaged harness and poor connection between terminal "8,24" of the HECU harness connector and chassis ground. Repair as necessary and then go to "Verification of vehicle Repair" procedure.

Component Inspection
1. Ignition "OFF".
2. Engine "ON".
3. Does warning lamp remain On?

YES - Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification of Vehicle Repair" procedure.

NO - Fault is intermittent caused by poor connection in power harness (IGN+). Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair as necessary and then go to "Verification of vehicle Repair" procedure.

Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode
2. Using a scantool, Clear DTC.
3. Operate the vehicle within DTC Detecting Condition in General Information.
4. Are any DTCs present?

YES - Go to the applicable troubleshooting procedure.

NO - System performing to specification at this time.