Diagnostic trouble code C1251 Land Cruiser

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK CONNECTION OF PUMP MOTOR WIRE HARNESS

CHECK RESISTANCE OF PUMP MOTOR WIRE HARNESS

RECONFIRM DTC

DTC C1251/51 Open in Pump Motor Circuit

Description

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

DTC Code DTC Detection Condition Trouble Area
C1251/51 There is an open in the motor system circuit (motor input circuit).
  1. Pump motor wire harness connection
  2. Brake booster with accumulator pump assembly
  3. Master cylinder solenoid (Skid control ECU)

Wiring diagram

Diagnostic trouble code C1251 Land Cruiser. Wiring diagram

Inspection procedure

NOTICE:

When replacing the master cylinder solenoid, perform zero point calibration .

HINT:

Remove the hydraulic brake booster assembly before the inspection (LHD: /RHD: ).

1.CHECK CONNECTION OF PUMP MOTOR WIRE HARNESS

  1. Using a screwdriver, remove the 2 plugs from the hydraulic brake booster assembly (LHD: /RHD:).

  1. Check the tightening torque of the 2 screws which tighten the wire harness connecting the hydraulic brake booster assembly and brake booster pump (LHD: /RHD:).

OK:

The harness is tightened to the specific torque.

Torque:

2.9 N*m{ 30 kgf*cm , 26 in.*lbf }

  NG  
RETIGHTEN SCREWS
 
OK  
   

2.CHECK RESISTANCE OF PUMP MOTOR WIRE HARNESS

Diagnostic trouble code C1251 Land Cruiser. Using a screwdriver, remove the 2 screws and pull the wire harness from the hydraulic brake booster assembly.

  1. Using a screwdriver, remove the 2 screws and pull the wire harness from the hydraulic brake booster assembly.

  1. Measure the resistance according to the value(s) in the table below.

    Standard Resistance:

    Tester Connection Condition Specified Condition
    Red wire terminal - Black wire terminal Always 2 ?
    Result
    Result Proceed to
    OK A
    NG LHD B
    RHD C
  B  
REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY
 
  C  
REPLACE BRAKE BOOSTER WITH ACCUMULATOR PUMP ASSEMBLY
 
A  
   

3.RECONFIRM DTC

  1. Reassemble the hydraulic brake booster assembly (LHD: /RHD: ).

  1. Install the hydraulic brake booster assembly (LHD: /RHD: ).

  1. Clear the DTC .

  1. Check if the same DTC is output .

    Result
    Result Proceed to
    DTC is not output A
    DTC is output LHD B
    RHD C
  B  
REPLACE MASTER CYLINDER SOLENOID
 
  C  
REPLACE MASTER CYLINDER SOLENOID
 
A  
   
USE SIMULATION METHOD TO CHECK