Lexus ES: Low or High Power Supply Voltage (C1241)
DESCRIPTION
If a malfunction in the power source circuit occurs, or a malfunction in communication with the skid control ECU (brake actuator assembly) or in a speed sensor occurs, the 4WD ECU assembly will prohibit operations by the fail-safe function.
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area |
|---|---|---|---|
| C1241 | Low or High Power Supply Voltage |
|
|
| Vehicle Condition | |||||
|---|---|---|---|---|---|
| Pattern 1 | Pattern 2 | Pattern 3 | Pattern 4 | ||
| Diagnosis Condition | At a vehicle speed of 3 km/h (2 mph) or more | ○ | - | - | - |
| With the IG1 terminal voltage 9.5 V or less | - | ○ | - | - | |
| With the IG1 terminal voltage 17 V or more | - | - | - | ○ | |
| Malfunction Status | Voltage of IG1 terminal is 9.5 V or less. | ○ | - | - | - |
| Communication with the skid control ECU (brake actuator assembly) is impossible. | - | ○ | - | ○ | |
| Vehicle speed sensor voltage is reduced. | - | - | ○ | - | |
| Detection Time | 10 seconds or more | - | 60 seconds or more | 3 seconds or more | |
| Number of Trips | 1 trip | 1 trip | 1 trip | 1 trip | |
HINT:
DTC will be output when conditions for any of the patterns in the table above are met.
WIRING DIAGRAM
CAUTION / NOTICE / HINT
NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.
PROCEDURE
| 1. | CHECK FOR DTC (CAN COMMUNICATION SYSTEM AND ELECTRONICALLY CONTROLLED BRAKE SYSTEM) |
(a) Check if CAN communication system DTCs are output.
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(b) Start the engine.
(c) Drive the vehicle, accelerate to a speed of 3 km/h (2 mph) or more for 60 seconds or more, and check if the speed sensor DTC (electronically controlled brake system DTC) is output.
Chassis > Brake/EPB > Trouble Codes| Result | Proceed to |
|---|---|
| Neither CAN communication system DTC nor speed sensor DTC (electronically controlled brake system DTC) is output | A |
| CAN communication system DTC is output | B |
| Speed sensor DTC (electronically controlled brake system DTC) is output | C |
| B | .gif) | GO TO CAN COMMUNICATION SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING) |
| C | | REPAIR CIRCUIT INDICATED BY OUTPUT CODE (ELECTRONICALLY CONTROLLED BRAKE SYSTEM) |
|
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| 2. | INSPECT BATTERY |
(a) Check the battery voltage.
Standard Voltage:
11 to 14 V
| NG | | CHECK CHARGING SYSTEM |
|
| 3. | CHECK HARNESS AND CONNECTOR (IG1 TERMINAL) |
| (a) Disconnect the G131 4WD ECU assembly connector. |
|
(b) Turn the engine switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard Voltage:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| G131-3 (IG1) - Body ground | Engine switch on (IG) | 11 to 14 V |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 4. | CHECK HARNESS AND CONNECTOR (GND TERMINAL) |
(a) Turn the engine switch off.
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| G131-4 (GND) - Body ground | Always | Below 1 Ω |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
|
| 5. | RECONFIRM DTC |
(a) Clear the DTC.
Chassis > Four Wheel Drive > Clear DTCs(b) Start the engine.
(c) Drive the vehicle, accelerate to a speed of 3 km/h (2 mph) or more, and check if the same DTC is output.
Chassis > Four Wheel Drive > Trouble Codes| Result | Proceed to |
|---|---|
| DTC is output | A |
| DTC is not output | B |
HINT:
Reinstall the sensor, connectors, etc. and restore the vehicle to its prior condition before rechecking DTCs.
| A | | REPLACE 4WD ECU ASSEMBLY |
| B | | CHECK FOR INTERMITTENT PROBLEMS |
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