C1242

BRAKE CONTROL: ELECTRONICALLY CONTROLLED BRAKE SYSTEM: C1241/41: Low Battery Positive Voltage

DTC C1241/41 - Low Battery Positive Voltage

DTC C1242/42 - Open in IG1 / IG2 Power Source Circuit

DESCRIPTION

If a malfunction is detected in the power supply circuit, the skid control ECU power source voltage drops, or there is insufficient voltage to operate either ABS main relay 1 or ABS main relay 2, the skid control ECU will store these codes.
These codes may be also be stored if the auxiliary battery voltage drops below 9.5 V.
If the power source voltage is too high, the skid control ECU will stop functioning and outputs no DTCs, and the ABS warning and brake warning / yellow (minor malfunction) lights remain on.
HINT: DTC C1256/57 (accumulator low voltage malfunction) may also be memorized if there is a drop in power source voltage.





WIRING DIAGRAM













INSPECTION PROCEDURE
NOTE: When replacing the skid control ECU, perform initialization and calibration of the linear solenoid valve. Initialization

PROCEDURE

1. CHECK HYBRID CONTROL SYSTEM
(a) Check if the hybrid control system DTC is output Hybrid Control System.
Result:






B -- INSPECT HYBRID CONTROL SYSTEM
A -- Continue to next step.
2. CHECK AUXILIARY BATTERY
(a) Check the auxiliary battery voltage.
Standard voltage:
11 to 14 V
NG -- CHARGE OR REPLACE AUXILIARY BATTERY
OK -- Continue to next step.
3. INSPECT SKID CONTROL ECU (IG AND +BI TERMINAL)
(a) Make sure that there is no looseness at the locking part and the connecting part of the connectors.





(b) Disconnect the skid control ECU connectors.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (IG OR +BI CIRCUIT)
OK -- Continue to next step.
4. INSPECT SKID CONTROL ECU (GND TERMINAL)
(a) Turn the power switch off.





(b) Make sure that there is no looseness at the locking part and the connecting part of the connector.
(c) Disconnect the skid control ECU connector.
(d) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)
OK -- Continue to next step.
5. INSPECT SKID CONTROL ECU (RELAY TERMINAL)





(a) Reconnect the skid control ECU connectors.
(b) Turn the power switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:






Result:






C -- REPAIR OR REPLACE HARNESS OR CONNECTOR (RELAY CIRCUIT)
B -- REPLACE SKID CONTROL ECU
A -- Continue to next step.
6. RECONFIRM DTC
(a) Turn the power switch off.
(b) Clear the DTCs.
(c) Turn the power switch on (IG).
(d) Check if the same DTC is recorded.
Result:





HINT: If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step.

B -- REPLACE SKID CONTROL ECU
A -- CHECK FOR INTERMITTENT PROBLEMS (SYMPTOM SIMULATION)