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Home >> Lincoln >> 2019 >> MKZ Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1871 (EPAS Guided Routine Testing) >> Pinpoint Tests >> Pinpoint Test A: PSCM DTC B1304 Electronic Power Assisted Steering System >> PSCM Circuit Information
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PSCM Circuit Information

WARNING: This page is about a different car, the 2018 Lincoln Navigator. However, it is still accessible from the selected car via links, so may be relevant.

Refer to POWER STEERING CONTROLS , for schematic and connector information.

Refer to Steering GSB for additional connector and wiring inspection tips.

CAUTION: Use the correct probe adapters when making measurements. Failure to use the correct probe adapters may cause damage to the connector.
Fig 1: PSCM-A Connector End View (C1463A)
G09694751Courtesy of FORD MOTOR CO.
Harness Side

Circuit Pin
GND (Ground) - GD108 1 (BLACK/VIOLET)
B+ (Battery Positive Voltage) - SBF02 2 (YELLOW/RED)
Fig 2: PSCM-B Connector End View (C1463B)
G08267516Courtesy of FORD MOTOR CO.
Harness Side

Circuit Pin
CAN- (Controller Area Network) - VDB26 3 (GRAY/BLUE)
CAN+ (Controller Area Network) - VDB25 2 (GREEN/ORANGE)
IGN START/RUN (Ignition START/RUN) - CBB18 1 (GRAY/ORANGE)
Fig 3: High-Current Battery Junction Box Connector End View (C1617D)
G09694753Courtesy of FORD MOTOR CO.
Harness Side

Circuit Pin
B+ (Battery Positive Voltage) - SBF02 1 (YELLOW/RED)
  1. A1: RECHECK THE PSCM DTCS 
    • Ignition ON, engine running.
    • Carry out the PSCM self-test.
    • Is DTC B1304:68 present in the PSCM? 
      Yes No
      Go to  A2. The system is operating correctly at this time. The DTC may have set due to a previous low battery voltage condition.
  2. A2: CHECK THE VEHICLE BATTERY AND CHARGING SYSTEM VOLTAGE 
    • Ignition ON, engine OFF.
    • Refer to BATTERY, MOUNTING AND CABLES and carry out Pinpoint Test A: Battery Condition Test (battery state of charge).
    • Does the battery pass the condition test (battery state of charge)? 
      Yes No
      Go to  A3. INSTALL a new battery. REFER to BATTERY, MOUNTING AND CABLES .
  3. A3: CHECK THE PSCM VOLTAGE SUPPLY 
    • Ignition OFF.
    • PSCM_A connector disconnected. (C1463A)
    • PSCM_B connector disconnected. (C1463B)
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) PSCM_A (C1463A) Connector, Harness Side (-)
      B+ - SBF02 (YELLOW/RED) - Pin 2 Ground
    • Measure the voltage between:
      (+) PSCM_B (C1463B) Connector, Harness Side (-)
      IGN START/RUN - CBB18 (GRAY/ORANGE) - Pin 1 Ground
    • Is each voltage measurement within 0.2 volt of the recorded battery voltage? 
      Yes No
      Go to  A4. VERIFY the PSCM fuses in the BJB and the high-current BJB are OK. If the fuses are OK, REPAIR the circuit.
      If the fuses are not OK, REFER to the Wiring Diagram Information to identify the circuit short.
  4. A4: CHECK THE PSCM GROUND CIRCUIT FOR AN OPEN 
    • Ignition OFF.
    • Disconnect the battery negative cable. Refer to the Battery Disconnect General Procedure in BATTERY, MOUNTING AND CABLES .
    • Measure the resistance between:
      (+) PSCM_A (C1463A) Connector, Harness Side (-)
      GND - GD108 (BLACK/VIOLET) - Pin 1 Ground
    • Is the resistance less than 3 ohms? 
      Yes No
      Go to  A5. REPAIR the circuit.
  5. A5: VERIFY PSCM POWER AND GROUND CONNECTIONS 
    • Using a good light source, inspect all PSCM electrical connectors for:
      • corrosion - install a new connector or terminal and clean the module pins.
      • damaged or bent pins - install new terminals or pins.
      • pushed-out pins - install new pins as necessary.
      • spread terminals - install new terminals as necessary.
    • PSCM_A connector connected. (C1463A) Make sure the connector seats and latches correctly.
    • PSCM_B connector connected. (C1463B) Make sure the connector seats and latches correctly.
    • Connect the battery negative cable. Refer to the Battery Disconnect General Procedure in BATTERY, MOUNTING AND CABLES .
    • Ignition ON, engine OFF.
    • Clear the PSCM DTCs.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Ignition ON, engine running.
    • Carry out the PSCM self-test.
    • Is DTC B1304:68 present in the PSCM? 
      Yes No
      The concern may be an intermittent condition with the PSCM wiring harness which cannot be detected by voltage or resistance checks.
      Go to  A6.      		 The system is operating correctly at this time. The concern may have been caused by a loose or corroded PSCM electrical connector or a wiring harness in-line electrical connector and was repaired during this procedure.
  6. A6: VERIFY PSCM WIRE HARNESS POWER AND GROUND CONNECTIONS 
    • Ignition OFF.
    • Disconnect and inspect the PSCM ground joint connection, clean or repair as necessary. Refer to Wiring Diagram Information POWER STEERING CONTROLS for ground joint information.
    • High-current Battery Junction Box connector disconnected. (C1617D)
    • Inspect the high-current BJB connection, clean or repair as necessary. Refer to Wiring Diagram Information POWER STEERING CONTROLS for high-current BJB joint information.
    • Using a good light source, inspect all PSCM electrical connectors for:
      • corrosion - install a new connector or terminal and clean the module pins.
      • damaged or bent pins - install new terminals or pins.
      • pushed-out pins - install new pins as necessary.
      • spread terminals - install new terminals as necessary.
    • Connect the PSCM ground joint connection. Make sure the connection is clean, tight and not cross-threaded.
    • High-current Battery Junction Box connector connected. (C1617D) Make sure the connector seats and latches correctly.
    • Ignition ON, engine OFF.
    • Clear the PSCM DTCs.
    • Ignition OFF.
    • Ignition ON, engine running.
    • Carry out the PSCM self-test.
    • Is DTC B1304:68 present in the PSCM? 
      Yes No
      Go to  A7. REPAIR the circuit.
  7. A7: VERIFY PSCM HARNESS FOR INTERMITTENT POWER AND GROUND CIRCUIT OPERATION 
    • Ignition ON, engine running.
    • Make sure the front wheels are on the ground and the vehicle is not being supported by other means.
      • Make sure the front tires are clean and dry.
      • Make sure the ground under the front tires is clean and dry.
    • Take the following measurement while turning the steering wheel back and forth, lock to lock, continuously at 1 revolution per second.
    • Measure the voltage between:
      (+) 12 Volt Vehicle Battery (-) 12 Volt Vehicle Battery
      Positive terminal Negative terminal
    • Record the measured battery voltage.
    • View the following PID while turning the steering wheel back and forth, lock to lock, continuously at 1 revolution per second.
    • Access the PSCM and monitor the MOD_SUP_V (VOLT) PID.
    • Compare the measured battery voltage with the PID display.
      NOTE: If the scan tool cannot display the PID reading due to no communication with the PSCM, select the No Action.
    • Do the measured battery voltage and the PID display differ by more than 1.5 volts? 
      Yes No
      INSTALL a new PSCM wiring harness.
      Go to  A8.      		 Go to  A10.
  8. A8: VERIFY NEW PSCM HARNESS FOR INTERMITTENT POWER AND GROUND CIRCUIT OPERATION 
    • Ignition ON, engine running.
    • Make sure the front wheels are on the ground and the vehicle is not being supported by other means.
      • Make sure the front tires are clean and dry.
      • Make sure the ground under the front tires is clean and dry.
    • Take the following measurement while turning the steering wheel back and forth, lock to lock, continuously at 1 revolution per second.
    • Measure the voltage between:
      (+) 12 Volt Vehicle Battery (-) 12 Volt Vehicle Battery
      Positive terminal Negative terminal
    • Record the measured battery voltage.
    • View the following PID while turning the steering wheel back and forth, lock to lock, continuously at 1 revolution per second.
    • Access the PSCM and monitor the MOD_SUP_V (VOLT) PID.
    • Compare the measured battery voltage with the PID display.
      NOTE: If the scan tool cannot display the PID reading due to no communication with the PSCM, select the No Action.
    • Do the measured battery voltage and the PID display differ by more than 1.5 volts? 
      Yes No
      Go to  A10. Go to  A9.
  9. A9: CHECK THE PSCM FOR DTCS 
    • Ignition ON, engine OFF.
    • Clear the PSCM DTCs.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Ignition ON, engine running.
    • Operate the system.
    • Carry out the PSCM self-test.
    • Is DTC B1304:68 present in the PSCM? 
      Yes No
      Go to  A10. The repair is complete.
  10. A10: CHECK FOR APPLICABLE SERVICE ARTICLES 
    • Ignition OFF.
    • Check OASIS for any applicable TSB, GSB, SSM or FSA.
    • Does a service article exist for DTC B1304:68? 
      Yes No
      DISCONTINUE this test and FOLLOW the service article instructions. DIAGNOSE the charging system. REFER to CHARGING SYSTEM - GENERAL INFORMATIONCHARGING SYSTEM - GENERAL INFORMATION .
      The PSCM wiring harness, related circuits and connectors are NOT a root cause for the PSCM B1304 DTC B1304. DTC B1304 DOES NOT require a new PSCM to be installed.
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