Pinpoint Test B: The ABS Module Does Not Respond To The Scan Tool

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Module Communications Network for schematic and connector information.

Refer to appropriate SYSTEM WIRING DIAGRAMS article, Vehicle Dynamic Systems for schematic and connector information.

Normal Operation 

The ABS module communicates with the scan tool through the high speed controller area network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the network connection to the ABS module. The ABS module shares the HS-CAN with the PCM, the accessory protocol interface module (APIM), the restraints control module (RCM), the occupant classification system module (OCSM), the 4X4 control module (if equipped), the headlamp control module (HCM) (if equipped), the steering angle sensor module (SASM) (if equipped) and the instrument cluster (IC). Voltage for the ABS module is provided by circuits CBB50 (YE/OG), SBB57 (RD) and SBB15 (WH/RD). Ground is provided by circuit GD121 (BK/YE).

This pinpoint test is intended to diagnose the following:

• Fuse
• Wiring, terminals or connectors
• ABS module

PINPOINT TEST B: THE ABS MODULE DOES NOT RESPOND TO THE SCAN TOOL 

1. B1 CHECK THE ABS MODULE VOLTAGE SUPPLY CIRCUITS FOR AN OPEN 
   • Key in OFF position.
   • Disconnect: ABS Module C135
   • Key in ON position.
   • Measure the voltage between the ABS module, harness side and ground as follows:

     Connector-Pin	Circuit
     C135-1	SBB15 (WH/RD)
     C135-25	SBB57 (RD)
     C135-30	CBB50 (YE/OG)

   • Are the voltages greater than 10 volts? 
   1. YES  : Go to  B2.
   2. NO  : VERIFY the battery junction box (BJB) fuse 15 (40A), fuse 50 (10A) or fuse 57 (40A) are OK. If OK, REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
2. B2 CHECK THE ABS MODULE GROUND CIRCUITS FOR AN OPEN 
   • Key in OFF position.
   • Measure the resistance between the ABS module, harness side and ground as follows:

     Connector-Pin	Circuit
     C135-13	GD121 (BK/YE)
     C135-38	GD121 (BK/YE)

   • Are the resistances less than 5 ohms? 
   1. YES  : Go to  B3.
   2. NO  : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
3. B3 CHECK THE HS-CAN CIRCUITS BETWEEN THE DATA LINK CONNECTOR (DLC) AND THE ABS MODULE FOR AN OPEN 
   Fig 1: Measuring Resistance Between ABS module C135-5, Circuit VDB04 (WH/BU) & DLC C251-6
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the ABS module C135-5, circuit VDB04 (WH/BU), harness side and the DLC C251-6, circuit VDB04 (WH/BU), harness side.
   Fig 2: Measuring Resistance Between ABS module C135-6, Circuit VDB05 (WH) & DLC C251-14
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the ABS module C135-6, circuit VDB05 (WH), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
   • Are the resistances less than 5 ohms? 
   1. YES  : Go to  B4.
   2. NO  : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
4. B4 CHECK FOR CORRECT ABS MODULE OPERATION 
   • Disconnect the ABS module connector.
   • Check for:
     • corrosion
     • damaged pins
     • pushed-out pins
   • Connect the ABS module connector and make sure it seats correctly.
   • Operate the system and verify the concern is still present.
   • Is the concern still present? 
   1. YES  : INSTALL a new ABS module. REFER to VEHICLE DYNAMIC SYSTEMS article. CLEAR the DTCs. REPEAT the network test with the scan tool.
   2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.