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 1827 (WH/LG) (HS-CAN +) and 1828 (PK/LG) (HS-CAN -) provide the network connection to the ABS module. The ABS module shares the HS-CAN with the PCM, the vehicle dynamics module (VDM) (if equipped), the instrument cluster (IC) and the fire suppression system module (FSSM) (if equipped). Voltage for the ABS module is provided by circuits 483 (RD), 601 (LB/PK) and 1003 (GY/YE) and ground is provided by circuit 57 (BK).

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 HS-CAN TERMINATION RESISTANCE 
   • Key in OFF position.
   NOTE: Failure to disconnect the battery will result in false resistance readings.
   • Disconnect the battery ground cable.
   • Disconnect the scan tool cable from the data link connector (DLC).
   Fig 1: Measuring Resistance
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the DLC C251-6, circuit 1827 (WH/LG), harness side and the DLC C251-14, circuit 1828 (PK/LG), harness side.
   • Is the resistance between 54 and 66 ohms? 
   1. YES  : Go to  B2.
   2. NO  : Go to  B4.
2. B2 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
     C135-8	1003 (GY/YE)
     C135-13	601 (LB/PK)
     C135-14	483 (RD)

   • Are the voltages greater than 10 volts? 
   1. YES  : Go to  B3.
   2. NO  : VERIFY the battery junction box (BJB) fuse 106 (40A) or fuse 109 (20A) and the central junction box (CJB) fuse 13 (10A) is OK. If OK, REPAIR the circuit in question. CONNECT the ABS module. CLEAR the DTCs. REPEAT the network test with the scan tool.
3. B3 CHECK THE ABS MODULE GROUND CIRCUITS FOR AN OPEN 
   • Key in OFF position.
   Fig 2: Checking Circuits For Open
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the ABS module, harness side and ground as follows:

     Connector-Pin	Circuit
     C135-12	57 (BK)
     C135-15	57 (BK)

   • Are the resistances less than 5 ohms? 
   1. YES  : Go to  B4.
   2. NO  : REPAIR the circuit in question. CONNECT the ABS module. CLEAR the DTCs. REPEAT the network test with the scan tool.
4. B4 CHECK THE HS-CAN CIRCUITS BETWEEN THE DATA LINK CONNECTOR (DLC) AND THE ABS MODULE FOR AN OPEN 
   Fig 3: Checking Circuit For Open
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the ABS module C135-18, circuit 1827 (WH/LG), harness side and the DLC C251-6, circuit 1827 (WH/LG), harness side.
   Fig 4: Checking Circuit For Open
   Courtesy of FORD MOTOR CO.
   • Measure the resistance between the ABS module C135-28, circuit 1828 (PK/LG), harness side and the DLC C251-14, circuit 1828 (PK/LG), harness side.
   • Are the resistances less than 5 ohms? 
   1. YES  : Go to  B5.
   2. NO  : REPAIR the circuit in question. CONNECT the ABS module. CLEAR the DTCs. REPEAT the network test with the scan tool.
5. B5 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.