C1252

BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM: C1252/52: Brake Booster Pump Motor on Time Abnormally Long

DTC C1252/52 - Brake Booster Pump Motor on Time Abnormally Long

DESCRIPTION

The motor relay (semiconductor relay) is built in the master cylinder solenoid and drivers the pump motor based on a signal from the skid control ECU.





HINT: The pump motor continues operation for the first 3 minutes, then repeats start and stop.

WIRING DIAGRAM





INSPECTION PROCEDURE
NOTE:
When replacing the master cylinder solenoid, perform zero point calibration Calibration.
HINT: When C1253/53, C1254/54, or C1256/56 is output together with C1252/52, inspect and repair the trouble area indicated by C1253/53, C1254/54, or C1256/56 first.

PROCEDURE

1. CHECK PUMP MOTOR OPERATION
(a) Turn the ignition switch off.
(b) Depress the brake pedal more than 20 times.
(c) Turn the ignition switch to the ON position.
(d) Check how the pump motor operates.
Result:






D -- RECONFIRM DTC
C -- READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE SENSOR)
B -- REPLACE MASTER CYLINDER SOLENOID AND BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY
A -- Continue to next step.
2. CHECK CONNECTION OF PUMP MOTOR WIRE HARNESS (MT+ / MT-)
(a) Using a screwdriver, remove the 2 plugs from the hydraulic brake booster assembly Disassembly.
(b) Check the tightening torque of the 2 screws which tighten the wire harness connecting the hydraulic brake booster assembly and the brake booster pump Disassembly.
OK:
The harness is tightened to the specific torque.
Torque: 2.9 Nm (30 kgf-cm, 26 in-lbf)
NG -- RETIGHTEN SCREWS UP
OK -- Continue to next step.
3. CHECK RESISTANCE OF PUMP MOTOR WIRE HARNESS (MT+ / MT-)




(a) Using a screwdriver, remove the 2 screws and pull the wire harness from the hydraulic brake booster assembly Disassembly.
(b) Measure the resistance between the red wire (MT+) and the black wire (MT-).
Standard resistance:
2 Ohms
NG -- REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY
OK -- Continue to next step.
4. READ VALUE USING TECHSTREAM (ACCUMULATOR PRESSURE SENSOR)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch to the ON position and push Techstream main switch ON.
(c) Select "Data List" mode on Techstream.

ABS/VSC/TRAC





(d) Check the accumulator output value.
Result:






C -- REPLACE MASTER CYLINDER SOLENOID AND BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY
B -- REPLACE HYDRAULIC BRAKE BOOSTER
A -- Continue to next step.
5. RECONFIRM DTC
(a) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.
(b) Turn the ignition switch off.
(c) Turn the ignition switch to the ON position.
(d) Wait for more than 5 minutes.
(e) Check if the same DTC is detected Reading and Clearing Diagnostic Trouble Codes.
HINT: Reinstall the sensors, connectors, etc. and restore the previous vehicle conditions before rechecking for DTCs.

Result:






B -- REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY
A -- REPLACE MASTER CYLINDER SOLENOID AND BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY