Code No.55: Pump motor locked (seizure of the pump motor or abnormality in the ABS-ECU current detecting circuit)

OPERATION

The pump motor operates if the motor relay 1 or motor relay 2 turn to ON.
The ABS-ECU monitors the pump motor (at 49 terminal).
The ABS-ECU monitors each of the power supply voltage (terminal No. 45) to the pump motor and the earth voltage (terminal No. 35) in order to determine if the pump motor is stuck.

DIAGNOSIS CODE SET CONDITIONS

The diagnosis code is set if the pump motor drive circuit is open or short, motor relay malfunction occurs, or the ABS-ECU internal circuit malfunction occurs, or the hydraulic brake booster (HBB) pump motor or master cylinder and hydraulic unit assembly malfunction occurs.

PROBABLE CAUSES

Damaged wiring harness or connector
Malfunction of the motor relay
Malfunction of the ABS-ECU
Malfunction of the pump motor [Integrated with the hydraulic brake booster (HBB)]
Malfunction of the master cylinder and hydraulic unit assembly [Integrated with the hydraulic brake booster (HBB)]

DIAGNOSIS

STEP 1. Check the sound of the HBB buzzer.

Q. Does the HBB buzzer sound?

	Check the pump motor for seizure, and replace the pump motor if necessary. Then go to Step 10.

	Go to Step 2.

STEP 2. Check ABS-ECU connector D-250, HBB connector B-107 and B-108 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?

	Go to Step 3.

	Repair the faulty connector or terminal. Then go to Step 10.

STEP 3. Check the HBB earth circuit at HBB harness connector B-107.

(1)Disconnect HBB connector B-107 and measure at the harness connector (component side).

(2)Measure the resistance between terminal 7 and body earth.
OK: Continuity (Less than 2 ohms)

Q. Is the check result normal?

	Go to Step 4.

	Repair the harness wire between HBB connector B-107 (terminal 7) and body earth. Then go to Step 10.

STEP 4. Check the HBB earth circuit at HBB harness connector B-108.

(1)Disconnect HBB connector B-108 and measure at the harness connector (component side).

(2)Measure the resistance between terminal 32 and body earth.
OK: Continuity (Less than 2 ohms)

Q. Is the check result normal?

	Go to Step 5.

	Repair the harness wire between HBB connector B-108 (terminal 32) and body earth. Then go to Step 10.

STEP 5. Check the HBB (continuity and resistance test of the pump motor).

Refer to

Q. Is the check result normal?

	Go to Step 7.

	Go to Step 6.

STEP 6. Check the pump motor and lead wire.

(1)Remove the HBB (Refer to

(2)Remove the pump motor and the lead wire from the HBB (Refer to

(3)Check the following items:

Confirm that the pump motor operates when the battery voltage is imposed at the pump motor terminal.
Confirm the continuity of the lead wire.

Q. Is the check result normal?

	Replace the master cylinder and hydraulic unit assembly (Refer to ). Then go to Step 10.

	Replace the pump motor or the lead wire (Refer to ). Then go to Step 10.

STEP 7. Check ABS-ECU connector D-250 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?

	Go to Step 8.

	Repair the faulty connector or terminal. Then go to Step 10.

STEP 8. Check the following harness wires.

The wire between HBB connector B-107 (terminal 4) and ABS-ECU connector D-250 (terminal 49)
The wire between HBB connector B-107 (terminal 6) and ABS-ECU connector D-250 (terminal 35)
The wire between HBB connector B-107 (terminal 8) and ABS-ECU connector D-250 (terminal 45)

Q. Is the check result normal?

	Go to Step 9.

	Repair or replace the faulty harness wire. Then go to 10.

STEP 9. Recheck for diagnosis code.

(1)Erase the diagnosis code.

(2)Recheck for diagnosis code.

Q. Is code No.55 set?

	Replace the ABS-ECU (Refer to GROUP 35B, ABS Control Unit ). Then go to Step 10.

	The procedure is complete.

STEP 10. Recheck for diagnosis code.

(1)Erase the diagnosis code.

(2)Recheck for diagnosis code.

Q. Is code No.55 set?

	Start over at Step 1.

	The procedure is complete.