C1242

BRAKE CONTROL: ELECTRONICALLY CONTROLLED BRAKE SYSTEM: C1241/41,C1242/42: Low Battery Positive Voltage

DTC C1241/41 - Low Battery Positive Voltage

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

DESCRIPTION

These codes are memorized when the power source voltage for the skid control ECU drops or the voltage for the ABS MAIN1 relay and ABS MAIN2 relay operation drops.
HINT: DTC C1256/57 (accumulator low pressure) may be memorized if the power source voltage drops.









WIRING DIAGRAM





INSPECTION PROCEDURE
NOTICE:
When replacing the skid control ECU, perform initialization of linear solenoid valve and calibration Programming and Relearning.

PROCEDURE

1. INSPECT BATTERY
(a) Check the battery voltage.
Standard voltage:
10 to 14 V
NG -- INSPECT CHARGING SYSTEM
OK -- Continue to next step.
2. CHECK DTC
(a) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(b) Turn the power switch OFF.
(c) Turn the power switch ON (IG).
(d) Check that the DTCs (electronically controlled brake system and HV control system) are recorded.

Result





C -- REPAIR CIRCUIT INDICATED BY OUTPUT CODE
B -- REPAIR HYBRID CONTROL SYSTEM
A -- Continue to next step.
3. CHECK WIRE HARNESS (IG AND DI CIRCUIT)




(a) Disconnect the A13 and A15 ECU connectors.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (IG OR DI CIRCUIT)
OK -- Continue to next step.
4. CHECK WIRE HARNESS (GND CIRCUIT)




(a) Disconnect the A13 and A15 ECU connectors.
(b) 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 BRAKE CONTROL POWER SUPPLY (FAIL TERMINAL)
(a) Connect the A13 and A15 ECU connectors.




(b) Connect the oscilloscope to terminal U27-13 (FAIL) of the brake control power supply.




(c) Check the signal waveform.
OK:
A waveform as shown in the figure should be output.
NG -- REPAIR BRAKE CONTROL POWER SUPPLY
OK -- Continue to next step.
6. RECONFIRM DTC
(a) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.
(b) Turn the power switch ON (IG).
(c) After 2 minutes or more have elapsed, drive the vehicle 5 km/h (3 mph) or more for 20 seconds.
(d) Check if the same DTCs are recorded Reading and Clearing Diagnostic Trouble Codes.

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 Problem Symptoms Table.

B -- REPLACE SKID CONTROL ECU
A -- END