Ford Mustang Service Manual: Hydraulic Control Unit

Anti-Lock Control

Refer to Wiring Diagrams Cell 42 , Anti-Lock Brake for schematic and connector information.

Special Tool(s)



Worldwide Diagnostic System Worldwide Diagnostic System (WDS) 418-F224, New Generation STAR (NGS) Tester 418-F052, or equivalent scan tool
73 Digital Multimeter or 73 Digital Multimeter or equivalent 105-R0051

Principles of Operation

The anti-lock brake control module receives wheel speed readings from each anti-lock brake sensor and processes this information to determine if an ABS event is necessary. The anti-lock brake sensor electrically senses each tooth of the anti-lock brake sensor indicators as it passes through the anti-lock brake sensor's magnetic field.

The anti-lock brake control module continuously monitors and compares the rotational speed of each wheel, and when it detects an impending wheel lock, modulates hydraulic brake pressure to the appropriate brake caliper. This is accomplished by the anti-lock brake control module triggering the hydraulic control unit (HCU) to open and close the appropriate solenoid valves. Once the affected wheel returns to normal speed, the anti-lock brake control module returns the solenoid valves to their normal position, and normal (base) braking resumes.

The anti-lock brake control module is self-monitoring. When the ignition switch is turned to the RUN position, the anti-lock brake control module will do a preliminary electrical check, and at approximately 12 km/h (8 mph) the pump motor is turned on for approximately one half-second. Any malfunction of the ABS will cause the ABS to shut off and the yellow ABS warning indicator to illuminate, however, normal power assisted braking remains.

The ABS control module has the ability to store multiple DTCs in memory.

Inspection and Verification

1. Verify the customer concern by operating the system.

2. Visually inspect for obvious signs of mechanical and electrical damage.

Visual Inspection Chart

Mechanical

Electrical
  • Low brake fluid
  • Anti-lock brake sensor
  • Anti-lock brake sensor indicator
  • Base brake system
  • Central junction box (CJB)Fuse:
  • 15 (10A)
  • 29 (15A)
  • 33 (15A)
  • 35 (15A)
  • Battery junction box (BJB) Fuse:
  • ABS 1 (50A)
  • ABS 2 (20A)
  • Circuitry
  • Damaged or corroded connectors
  • Yellow ABS warning indicator
  • Loose grounds

3. If the concern remains after the inspection, connect the scan tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the scan tool menu. If the scan tool does not communicate with the vehicle:

1. Check that the program card is correctly installed.

2. Check the connections to the vehicle.

3. Check the ignition switch position.

4. If the scan tool still does not communicate with the vehicle, refer to the scan tool Manual.

5. Carry out the DATA LINK DIAGNOSTIC TEST. If the scan tool responds with:

1. CKT914, CKT915 or CKT70 = ALL ECUS NO RESP/NOT EQUIP.

2. NO RESP/NOT EQUIP for the anti-lock brake control module, Go To Pinpoint Test A .

3. SYSTEM PASSED, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and carry out self-test diagnostics for the anti-lock brake control module.

6. If the DTCs retrieved are related to the concern, go to the Anti-Lock Brake Control Module Diagnostic Trouble Code (DTC) Reference Chart to continue diagnostics.

7. If no DTCs related to the concern are retrieved, GO to Symptom Chart to continue diagnostics.

Anti-Lock Brake Control Module Diagnostic Trouble Code (DTC) Index

NOTE: If a wheel speed signal fault or a pump motor fault is detected, the yellow ABS warning indicator cannot be reset with the key OFF and key ON method. The vehicle must be driven over 12 km/h (8 mph) for the anti-lock brake control module to carry out a re-check of the system before the yellow ABS warning indicator is turned OFF.

Anti-Lock Brake Control Module Diagnostic Trouble Code (DTC) Index

DTC Description Source Action
B1318 Battery Voltage Low ABS Go To Pinpoint Test C .
B1342 ECU Is Defective ABS INSTALL a new anti-lock brake control module; REFER to Module . REPEAT the self-test.
B1484 Brake Pedal Input Open Circuit ABS Go To Pinpoint Test D . REPAIR the DTCs retrieved.
B1596 Repair Continuous Codes ABS Go To Pinpoint Test E .
C1095 ABS Hydraulic Pump Motor Circuit Failure ABS Go To Pinpoint Test F .
C1145 RF Anti-Lock Brake Sensor Input Circuit Failure ABS Go To Pinpoint Test F .
C1155 LF Anti-Lock Brake Sensor Input Circuit Failure ABS Go To Pinpoint Test F .
C1165 RR Anti-Lock Brake Sensor Input Circuit Failure ABS Go To Pinpoint Test F .
C1175 LR Anti-Lock Brake Sensor Input Circuit Failure ABS Go To Pinpoint Test F .
C1222 Anti-Lock Brake Sensor Mismatch ABS Go To Pinpoint Test G .
C1233 LF Anti-Lock Brake Sensor Input Signal Missing ABS Go To Pinpoint Test H .
C1234 RF Anti-Lock Brake Sensor Input Signal Missing ABS Go To Pinpoint Test H .
C1235 RR Anti-Lock Brake Sensor Input Signal Missing ABS Go To Pinpoint Test H .
C1236 LR Anti-Lock Brake Sensor Input Signal Missing ABS Go To Pinpoint Test H .
C1266 ABS Valve Power Relay Circuit Failure ABS Go To Pinpoint Test I .

Anti-Lock Brake Control Module Parameter Identification (PID) Index

PID Description Expected Value
CCNTABS Number of Continuous DTCS in the Anti-Lock Brake Control Module one count per bit
BOO_ABS Brake Switch Input OFF, ON
PMP_MTR ABS Pump Motor OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFBG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONOG, ON-BG, ONOBG
VLV_CTR ABS Valve Control Relay OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFBG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONOG, ON-BG, ONOBG
LF_WSPD LF Wheel Speed 0-255 MPH
RF_WSPD RF Wheel Speed 0-255 MPH
LR_WSPD LR Wheel Speed 0-255 MPH
RR_WSPD RR Wheel Speed 0-255 MPH
ABSLF_I LF ABS Inlet Valve OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFBG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONOG, ON-BG, ONOBG
ABSLF_O LF ABS Outlet Valve OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFBG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONOG, ON-BG, ONOBG
ABSRF_I RF ABS Inlet Valve OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFBG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONOG, ON-BG, ONOBG
ABSRF_O RF ABS Outlet Valve OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFBG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONOG, ON-BG, ONOBG
ABSR_I Rear ABS Inlet Valve OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFBG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONOG, ON-BG, ONOBG
ABSR_O Rear ABS Outlet Valve OFF---, OFFO--, OFF-B-, OFF--G, OFFO-G, OFFBG, OFFOBG, ON---, ONO--, ON-B-, ON--G, ONOG, ON-BG, ONOBG

Anti-Lock Brake Control Module Active Command Index

Active Command Display Action
ABS OUTPUT CONTROL ABS POWER OFF, ON
  DSBL TOG OFF, ON
  LF INLET OFF, ON
  LF OUTLET OFF, ON
  RF INLET OFF, ON
  RF OUTLET OFF, ON
  R INLET OFF, ON
  R OUTLET OFF, ON

Symptom Chart

NOTE: Refer to the Wiring Diagrams for connector numbers stated in the Pinpoint tests.

Condition Possible Sources Action
  • No communication with the antilock brake control module
  • CJB Fuse 29 (15A).
  • Circuitry.
  • Anti-lock brake control module.
  • Go To Pinpoint Test A .
  • Unable to enter self-test.
  • Anti-lock brake control module
  • Go To Pinpoint Test B .
  • The yellow ABS warning indicator does not self-check
  • Circuitry.
  • Anti-lock brake control module.
  • Instrument cluster
  • Go To Pinpoint Test J .
  • Spongy brake pedal with no warning indicator
  • Air in the brake system.
  • Base brake system
  • Go To Pinpoint Test K .
  • Poor vehicle tracking during anti-lock function
  • Air in the brake system.
  • Hydraulic control unit (HCU)
  • Base brake system
  • Go To Pinpoint Test L .

Pinpoint Tests

PINPOINT TEST A: NO COMMUNICATION WITH THE ANTI-LOCK BRAKE CONTROL MODULE

Test Step Result / Action to Take
A1 CHECK CIRCUIT 601 (LB/PK) FOR AN OPEN Yes

GO to A2 .

No

REPAIR the circuit.

REPEAT the selftest.
  • Key in OFF position.
  • Disconnect: Anti-Lock Brake Control Module C135.
  • Key in ON position.
  • Measure the voltage between anti-lock brake control module C135 Pin 8, Circuit 601 (LB/PK), harness side and ground.


  • Is the voltage greater than 10 volts?
A2 CHECK THE ANTI-LOCK BRAKE CONTROL MODULE GROUNDS Yes

INSTALL a new anti-lock brake control module; REFER to Module .

REPEAT the selftest.

No

REPAIR the circuit in question.

REPEAT the selftest.
  • Measure the resistance between anti-lock brake control module C135 Pin 12, Circuit 1205 (BK), harness side and ground; and between anti-lock brake control module C135 Pin 15, Circuit 397 (BK/WH), harness side and ground.


  • Are the resistances less than 5 ohms?

PINPOINT TEST B: UNABLE TO ENTER SELF-TEST

Test Step Result / Action to Take
B1 CHECK THE COMMUNICATIONS TO THE ANTI-LOCK BRAKE CONTROL MODULE Yes

INSTALL a new anti-lock brake control module; REFER to Module . REPEAT the self-test.

No

Go To Pinpoint Test A .
  • Check the communications to the anti-lock brake control module.
  • Does the scan tool communicate with the anti-lock brake control module?

PINPOINT TEST C: DTC B1318, BATTERY VOLTAGE LOW

Test Step Result / Action to Take
C1 CHECK BATTERY VOLTAGE Yes

GO to C2 .

No
  • Measure the battery voltage between the positive and negative battery posts with the key ON engine OFF (KOEO), and with the engine running.


  • Is the battery voltage between 10 and 13 volts with KOEO, and between 11 and 17 volts with the engine running?
C2 CHECK THE VOLTAGE TO THE ANTI-LOCK BRAKE CONTROL MODULE Yes

GO to C3 .

No

REPAIR the circuit.

CLEAR the DTCs.

REPEAT the selftest.
  • Key in OFF position.
  • Disconnect: Anti-Lock Brake Control Module C135.
  • Key in ON position.
  • Measure the voltage between anti-lock brake control module C135 Pin 8, Circuit 601 (LB/PK), harness side and ground.


  • Is the voltage greater than 10 volts?
C3 CHECK THE ANTI-LOCK BRAKE CONTROL MODULE GROUNDS Yes

INSTALL a new anti-lock brake control module; REFER to Module .

REPEAT the selftest.

No

REPAIR the circuit in question.

CLEAR the DTCs.

REPEAT the selftest.
  • Measure the resistance between anti-lock brake control module C135 Pin 12, Circuit 1205 (BK), harness side and ground; and between anti-lock brake control module C135 Pin 15, Circuit 397 (BK/WH), harness side and ground.


  • Are the resistances less than 5 ohms?

PINPOINT TEST D: DTC B1484, BRAKE PEDAL INPUT OPEN CIRCUIT

Test Step Result / Action to Take
D1 CHECK THE STOPLAMPS FOR CORRECT OPERATION Yes

GO to D2 .

No
  • Depress the brake pedal while checking the stoplamps.
  • Do the stop lamps illuminate?
D2 CHECK THE BRAKE PEDAL INPUT TO THE ANTI-LOCK BRAKE CONTROL MODULE Yes

INSTALL a new anti-lock brake control module; REFER to Module .

REPEAT the self-test.

No

REPAIR Circuit 511 (LG) and Circuit 810 (RD/LG) as necessary. CLEAR the DTCs. REPEAT the self-test.
  • Key in OFF position.
  • Disconnect: Anti-Lock Brake Control Module C135.
  • Measure the voltage between anti-lock brake control module C135 Pin 6, Circuit 511 (LG), harness side and ground, while depressing and releasing the brake pedal.


  • Is the voltage greater than 10 volts with the brake pedal depressed and zero volts with the brake pedal released?

PINPOINT TEST E: DTC C1095, ABS HYDRAULIC PUMP MOTOR FAILURE

Test Step Result / Action to Take
E1 CHECK THE PUMP MOTOR FOR CONTINUOUS OPERATION Yes

INSTALL a new anti-lock brake control module; REFER to Module .

REPEAT the selftest.

No

GO to E2 .
  • Check the pump motor for continuous operation.
  • Is the pump motor running continuously?
E2 CHECK CIRCUIT 534 (YE/LG) FOR AN OPEN Yes

GO to E3 .

No

REPAIR the circuit.

CLEAR the DTCs.

REPEAT the selftest.
  • Key in OFF position.
  • Disconnect: Anti-Lock Brake Control Module C135.
  • Measure the voltage between anti-lock brake control module C135 Pin 13, Circuit 534 (YE/LG), harness side, and ground.


  • Is the voltage greater than 10 volts?
E3 CHECK CIRCUIT 1205 (BK) FOR AN OPEN Yes

GO to E4 .

No

REPAIR the circuit.

CLEAR the DTCs.

REPEAT the selftest.
  • Measure the resistance between anti-lock brake control module C135 Pin 12, Circuit 1205 (BK), harness side and ground.


  • Is the resistance less than 5 ohms?
E4 CHECK THE PUMP MOTOR FOR OPERATION Yes

INSTALL a new anti-lock brake control module; REFER to Module .

REPEAT the selftest.

No

INSTALL a new HCU; REFER to Hydraulic Control Unit . CLEAR the DTCs. REPEAT the self-test.
  • Disconnect: Pump Motor Connector.
  • Connect a 30A fused heavy jumper wire between the positive battery post and pump motor connector Pin 1 (component side); and momentarily connect a heavy jumper between negative battery post and pump motor connector Pin 2 (component side).


  • Does the pump motor operate?

PINPOINT TEST F: DTC C1145 (RF), C1155 (LF), C1165 (RR), C1175 (LR), ANTI-LOCK BRAKE SENSOR INPUT CIRCUIT FAILURE

Test Step Result / Action to Take
F1 CHECK THE SUSPECT ANTI-LOCK BRAKE SENSOR CIRCUIT FOR SHORT TO POWER Yes

REPAIR the circuit in question.

CLEAR the DTCs. REPEAT the selftest.

No

GO to F2 .
  • Key in OFF position.
  • Disconnect: Anti-Lock Brake Control Module C135.
  • Key in ON position.
  • Measure the voltage between anti-lock brake control module C135 Pins, harness side and ground as follows:


  • Is any voltage present?
F2 CHECK THE SUSPECT ANTI-LOCK BRAKE SENSOR CIRCUIT FOR SHORT TO GROUND Yes

GO to F4 .

No

GO to F3 .
  • Key in OFF position.
  • Measure the resistance between anti-lock brake control module C135 Pins, harness side and ground as follows:


  • Is the resistance greater than 10,000 ohms?
F3 CHECK THE SUSPECT ANTI-LOCK BRAKE SENSOR FOR A SHORT TO GROUND Yes

If RF, REPAIR Circuit 514 (YE/RD) and Circuit 516 (YE/BK), as necessary. CLEAR the DTCs.

REPEAT the self-test. If LF, REPAIR Circuit 521 (TN/OG) and Circuit 522 (TN/BK), as necessary. CLEAR the DTCs. REPEAT the self-test. If RR, REPAIR Circuit 494 (TN/LG) and Circuit 492 (BN), as necessary.

CLEAR the DTCs. REPEAT the selftest.

If LR, REPAIR Circuit 496 (OG) and Circuit 499 (GY/BK), as necessary. CLEAR the DTCs.

REPEAT the self-test.

No

INSTALL a new anti-lock brake sensor; REFER to Sensor-Front or Sensor-Rear . CLEAR the DTCs.

REPEAT the self-test.
  • Disconnect: Suspect Anti-Lock Brake Sensor.
  • Measure the resistance between suspect anti-lock brake sensor Pin 1 (component side) and ground.


  • Is the resistance greater than 10,000 ohms?
F4 CHECK THE SUSPECT ANTI-LOCK BRAKE SENSOR CIRCUIT FOR FOR AN OPEN Yes

GO to F5 .

No

REPAIR the circuit in question.

CLEAR the DTCs. REPEAT the selftest.
  • Key in OFF position.
  • Measure the resistance between anti-lock brake control module C135 pins, harness side and suspect anti-lock brake sensor, harness side as follows:


  • Are the resistances less than 5 ohms?
F5 CHECK THE ANTI-LOCK BRAKE SENSOR Yes

INSTALL a new anti-lock brake control module; REFER to Module .

REPEAT the self-test.

No

INSTALL a new anti-lock brake sensor; REFER to Sensor-Front or Sensor-Rear . CLEAR the DTCs.

REPEAT the self-test.
  • Measure the resistance between suspect anti-lock brake sensor Pin 1 (component side) and suspect anti-lock brake sensor Pin 2 (component side).


  • Is the resistance between 1280 and 1920 (front) or 1830 and 2760 (rear) ohms?

PINPOINT TEST G: DTC C1222, ANTI-LOCK BRAKE SENSOR MISMATCH

Test Step Result / Action to Take
G1 CHECK THE VEHICLE COMPONENTS Yes

GO to G2 .

No

REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.
  • Check for correct wheel and tire size, front-to-rear and side-toside.
  • Check for excessive bearing end play.
  • Check the anti-lock brake sensor indicator for a deformation or missing teeth.
  • Are the conditions OK?
G2 TEST DRIVE THE VEHICLE Yes

INSTALL a new anti-lock brake control module; REFER to Module . REPEAT the self-test.

No

If another DTC is retrieved, GO to the Anti-Lock Brake Control Module Diagnostic Trouble Code (DTC) index.

If no DTCs are retrieved, the system is OK.
  • Enter the following diagnostic mode on the diagnostic tool: CLEAR the DTCs.
  • Key in OFF position.
  • Key in ON position.
  • Test drive the vehicle over 24 kph (15 mph).
  • Enter the following diagnostic mode on the diagnostic tool: Retrieve DTCs.
  • Is DTC C1222 retrieved?

PINPOINT TEST H: DTC C1233 (LF), C1234 (RF), C1235 (RR), C1236 (LR), ANTI-LOCK BRAKE SENSOR INPUT SIGNAL MISSING

Test Step Result / Action to Take
H1 CHECK THE SUSPECT ANTI-LOCK BRAKE SENSOR Yes

GO to H2 .

No

REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.
  • Check the suspect anti-lock brake sensor mounting.
  • Check the suspect anti-lock brake sensor for excessive dirt build up, obstructions, and damage.
  • Is the suspect anti-lock brake sensor and mounting OK?
H2 CHECK THE SUSPECT ANTI-LOCK BRAKE SENSOR INDICATOR Yes

GO to H3 .

No

INSTALL a new anti-lock brake sensor indicator; REFER to Sensor-Front or Sensor-Rear . CLEAR the DTCs.

REPEAT the self-test.
  • Check the suspect anti-lock brake sensor indicator for corrosion, nicks, bridged teeth, damaged teeth, correct mounting, and alignment with the anti-lock brake sensor.
  • Check the air gap and bearing end play.
  • Is the suspect anti-lock brake sensor indicator OK?
H3 CHECK THE ANTI-LOCK BRAKE SENSOR OUTPUT Yes

INSTALL a new anti-lock brake control module; REFER to Module . REPEAT the self-test.

No

INSTALL a new anti-lock brake sensor; REFER to Sensor-Front or Sensor-Rear . CLEAR the DTCs.

REPEAT the self-test.
  • Key in ON position.
  • Enter the following diagnostic mode on the diagnostic tool: CLEAR the DTCs..
  • Key in OFF position.
  • Key in ON position.
  • Have an assistant monitor the anti-lock brake control module PIDs LF_WSPD, RF_WSPD, LR_WSPD, and RR_WSPD while driving at various speeds.
  • NOTE: The vehicle must be driven 16 km/h (10 miles) during this test step.
  • Test drive the vehicle for 16 kmh (10 miles).
  • Are the anti-lock brake control module PIDs approximately the same at all times?

PINPOINT TEST I: ABS VALVE POWER RELAY CIRCUIT FAILURE

Test Step Result / Action to Take
I1 CHECK CIRCUIT 534 (YE/LG) FOR AN OPEN Yes

GO to I2 .

No

REPAIR the circuit. CLEAR the DTCs. REPEAT the selftest.
  • Key in OFF position.
  • Disconnect: Anti-Lock Brake Control Module C135.
  • Measure the voltage between anti-lock brake control module C135 Pin 13, Circuit 534 (YE/LG), harness side and ground.


  • Is the voltage greater than 10 volts?
I2 CHECK CIRCUIT 532 (OG/YE) FOR AN OPEN Yes

REPAIR the open in Circuit 532 (OG/YE). CLEAR the DTCs. REPEAT the self-test.

No

GO to I3 .
  • Key in OFF position.
  • Key in ON position.
  • Measure the voltage between anti-lock brake control module C135 Pin 14, Circuit 532 (OG/YE), harness side and ground.


  • Is the voltage less than 5 volts?
I3 CHECK CIRCUIT 1205 (BK) FOR AN OPEN Yes

INSTALL a new anti-lock brake control module.

REFER to Module in this section. CLEAR the DTCs.

REPEAT the self-test.

No

REPAIR the circuit. CLEAR the DTCs. REPEAT the selftest.
  • Measure the resistance between anti-lock brake control module C135 Pin 12, Circuit 1205 (BK), harness side and ground.


  • Is the resistance less than 5 ohms?

PINPOINT TEST J: THE YELLOW ABS WARNING INDICATOR DOES NOT SELF-CHECK

Test Step Result / Action to Take
J1 CHECK THE ABS WARNING INDICATOR CIRCUITRY Yes

INSTALL a new anti-lock brake control module; REFER to Module . TEST the system for normal operation.

No
  • Key in OFF position.
  • Disconnect: Anti-Lock Brake Control Module C135.
  • Key in ON position.
  • Depress and release the shorting bar connector internal to the anti-lock brake control module C135, harness side, while checking the yellow ABS warning indicator in the instrument cluster.
  • Does the yellow ABS indicator illuminate with the shorting bar released and turn OFF with the shorting bar depressed?

PINPOINT TEST K: SPONGY BRAKE PEDAL WITH NO WARNING INDICATOR

Test Step Result / Action to Take
K1 CHECK THE VEHICLE COMPONENTS Yes

GO to K2 .

No

REPAIR as necessary. TEST the system for normal operation.
  • Check the brake pedal and power booster/brake master cylinder for correct attachment.
  • Are the components OK?
K2 BLEED THE BRAKE SYSTEM Yes

INSTALL a new HCU; REFER to Hydraulic Control Unit . TEST the system for normal operation.

No

The brake system is OK. TEST the system for normal operation.
  • Bleed the brake system
  • Check for spongy brake pedal.
  • Is the brake pedal spongy?

PINPOINT TEST L: POOR VEHICLE TRACKING DURING ANTI-LOCK

FUNCTION

Test Step Result / Action to Take
L1 BLEED THE BRAKE SYSTEM Yes

GO to L2 .

No

The brake system is OK. TEST the system for normal operation.
  • Bleed the brake system.
  • Check for vehicle tracking poorly.
  • Does the vehicle track poorly?
L2 CHECK THE LF ABS VALVE OPERATION Yes

INSTALL a new HCU; REFER to Hydraulic Control Unit . TEST the system for normal operation.

No

GO to L3 .
  • Lift the vehicle and rotate all the wheels to make sure they rotate freely (the vehicle must be in neutral).
  • NOTE: Trigger must be depressed twice.

    Each press will run the pump motor for two seconds.

  • Trigger the anti-lock brake control module active command PMP MOTOR ON for four seconds.
  • Apply moderate brake pedal effort.
  • Have an assistant attempt to rotate the LF wheel while the pump motor is running.
  • Does the LF wheel rotate?
L3 CHECK THE LF ABS VALVE RELEASE Yes

GO to L4 .

No

GO to L8 .
  • Apply moderate brake pedal effort.
  • Trigger the anti-lock brake control module active command LF INLET and LF OUTLET.
  • NOTE: The scan tool will energize the valves for only two seconds per trigger press.
  • Have an assistant rotate the LF wheel immediately after depressing trigger.
  • Does the LF wheel rotate?
L4 CHECK THE RF ABS VALVE OPERATION Yes

INSTALL a new HCU; REFER to Hydraulic Control Unit . TEST the system for normal operation.

No

GO to L5 .
  • NOTE: Trigger must be depressed twice.

    Each press will run the pump motor for two seconds.

  • Trigger the anti-lock brake control module active command PMP MOTOR ON for four seconds.
  • Apply moderate brake pedal effort.
  • Have an assistant attempt to rotate the RF wheel while the pump motor is running.
  • Does the RF wheel rotate?
L5 CHECK THE RF ABS VALVE RELEASE Yes

GO to L6 .

No

GO to L8 .
  • Apply moderate brake pedal effort.
  • Trigger the anti-lock brake control module active command RF INLET and RF OUTLET.
  • NOTE: The scan tool will energize the valves for only two seconds per trigger press.
  • Have an assistant rotate the RF wheel immediately after depressing trigger.
  • Does the RF wheel rotate?
L6 CHECK THE REAR ABS VALVE OPERATION Yes

INSTALL a new HCU; REFER to Hydraulic Control Unit . TEST the system for normal operation.

No

GO to L7 .
  • NOTE: Trigger must be depressed twice.Each press will run the pump motor for two seconds.
  • Trigger the anti-lock brake control module active command PMP MOTOR ON for four seconds.
  • Apply moderate brake pedal effort.
  • Have an assistant attempt to rotate the LR and RR wheels while the pump motor is running.
  • Does the LR or RR wheel rotate?
L7 CHECK THE REAR ABS VALVE RELEASE Yes

The ABS system is operating correctly.

No

GO to L8 .
  • Apply moderate brake pedal effort.
  • Trigger the anti-lock brake control module active command R INLET and R OUTLET.
  • NOTE: The scan tool will energize the valves for only two seconds per trigger press.
  • Have an assistant rotate the LR and RR wheels immediately after depressing trigger.
  • Does the LR or RR wheel rotate?
L8 CHECK FOR DTCS Yes

GO to the Anti-Lock Brake Control Module Diagnostic Trouble Code (DTC) Index.

No

INSTALL a new HCU; REFER to Hydraulic Control Unit . TEST the system for normal operation.
  • Carry out the anti-lock brake control module self-test.
  • Are any DTCs retrieved?
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