Code No.C1273: Pump motor driver circuit malfunction

OPERATION

The ABS-ECU contains the power supply circuit (terminal No.25) for the motor pump. The motor pump is energised by the pump relay, which is incorporated in the ABS-ECU.
The pump relay, which is incorporated in the ABS-ECU, is always energising the motor pump unless the initial check is in progress when the ignition switch is turned on, or the recurrent system check is in progress.

DIAGNOSIS CODE SET CONDITIONS

These diagnosis codes will be set under the cases below.

If the voltage, which is created by the pump motor, is abnormal after the motor relay is turned on, the ECU determines that the motor relay is stuck off, and sets this diagnosis code.

PROBABLE CAUSES

The most likely causes for these diagnosis codes to set are:

Damaged wiring harness or connector
Malfunction of the hydraulic unit (integrated with ABS-ECU)

DIAGNOSIS PROCEDURE

STEP 1. Check ABS-ECU connector A-05 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?

Go to Step 2.

Repair or replace the damaged component(s). Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - Connector Inspection Service Points

STEP 2. Voltage measurement at ABS-ECU connector A-05.

(1)Disconnect the connector A-05, and connect special tool ABS Check Harness (MB991951) to the wiring harness-side connector.

note

Connect special tool ABS Check Harness (MB991951) to the ABS-ECU.

(2)Measure the voltage between terminal 25 and earth.
OK: System voltage

Q. Is the result normal?

Go to Step 3.

Repair the wiring harness between the ABS-ECU and fusible link No.3.

STEP 3. Check whether the diagnosis code is reset.

caution

Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.

(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check if the diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.
(7)Disconnect M.U.T.-III.

Q. Is code No.C1273 set?

Replace the hydraulic unit (integrated with ABS-ECU) (Refer to

The malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction