Pinpoint Test - AF DTC: U0028:88

Diagnostic Overview 

Refer to Supplemental Restraint System for schematic and connector information.

Normal Operation and Fault Conditions 

The RCM supplies the stability/traction control system with the yaw rate, roll rate, lateral and longitudinal accelerometer over a dedicated CAN. If the RCM detects a fault with communications with the dedicated CAN circuits, it sets DTC U0028:88.

The RCM does not request the IPC to illuminate the airbag warning indicator if DTC U0028:88 is set.

DTC Fault Trigger Conditions 

Possible Sources 

• Wiring, terminals or connectors
• ABS module
• RCM

Visual Inspection and Diagnostic Pre-checks 

• Inspect for damaged wiring harness(es)
• Inspect for a loose or damaged ABS module connector

PINPOINT TEST A : U0028:88 

1. WARNING: Incorrect repair techniques or actions can cause an accidental Supplemental Restraint System (SRS) deployment. Never compromise or depart from these instructions. Failure to precisely follow all instructions could result in serious personal injury from an accidental deployment.
2. NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.
3. NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test.
4. NOTE: Only disconnect or reconnect SRS components when instructed to do so within a pinpoint test step. Failure to follow this instruction may result in incorrect diagnosis of the SRS.
5. NOTE: Always make sure the correct SRS component is being installed. Parts released for other vehicles may not be compatible even if they appear physically similar. Check the part number listed in the Ford parts catalog to make sure the correct component is being installed. If an incorrect SRS component is installed, Diagnostic Trouble Codes (DTCs) may set.
6. NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.
7. A1 RETRIEVE RCM (RESTRAINTS CONTROL MODULE) DIAGNOSTIC TROUBLE CODES (DTCS)
   
   
   • Ignition ON.
   • Using a diagnostic scan tool, perform RCM self-test.

   Was DTC U0028:88 retrieved on-demand during self-test? 

   Yes	This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self-test. GO to  A2

   No	This is an intermittent fault when present as a CMDTC only. GO to  A9

8. A2 CHECK THE DEDICATED CAN (CONTROLLER AREA NETWORK) CIRCUITS FOR AN OPEN
   
   
   • Ignition OFF.
   • Depower the SRS. REFER to: Supplemental Restraint System (SRS) Depowering and Repowering  .
   • Disconnect RCM C310A and C310B .
   • Disconnect ABS Module C135 .
   • Measure:

     Positive Lead	Measurement / Action	Negative Lead
     C135-32	Courtesy of FORD MOTOR COMPANY	C310B-60
     C135-33	Courtesy of FORD MOTOR COMPANY	C310B-59

   Are the resistances less than 3 ohms? 

   Yes

   GO to  A3

   No	REPAIR the affected circuit. Refer to Connector Repair Procedures for schematic and connector information. GO to  A10

9. A3 CHECK THE DEDICATED CAN (CONTROLLER AREA NETWORK) CIRCUITS FOR A SHORT TO VOLTAGE
   
   
   • Repower the SRS. Do not prove out the SRS at this time. REFER to: Supplemental Restraint System (SRS) Depowering and Repowering  .
   • Ignition ON.
   • Measure:

     Positive Lead	Measurement / Action	Negative Lead
     C135-32	Courtesy of FORD MOTOR COMPANY	Ground
     C135-33	Courtesy of FORD MOTOR COMPANY	Ground

   Is any voltage present? 

   Yes	REPAIR the affected circuit. GO to  A10

   No

   GO to  A4

10. A4 CHECK THE DEDICATED CAN (CONTROLLER AREA NETWORK) CIRCUITS FOR A SHORT TO GROUND
    
    
    • Ignition OFF.
    • Measure:

      Positive Lead	Measurement / Action	Negative Lead
      C135-32	Courtesy of FORD MOTOR COMPANY	Ground
      C135-33	Courtesy of FORD MOTOR COMPANY	Ground

    Are the resistances greater than 10, 000 ohms? 

    Yes

    GO to  A5

    No	REPAIR the affected circuit. Refer to Connector Repair Procedures for schematic and connector information. GO to  A10

11. A5 CHECK FOR A SHORT BETWEEN THE DEDICATED CAN (CONTROLLER AREA NETWORK) CIRCUITS
    
    
    • Measure:

      Positive Lead	Measurement / Action	Negative Lead
      C135-32	Courtesy of FORD MOTOR COMPANY	C135-33

    Is the resistance greater than 10, 000 ohms? 

    Yes

    GO to  A6

    No	REPAIR the affected circuits. Refer to Connector Repair Procedures for schematic and connector information. GO to  A10

12. A6 CHECK THE ABS (ANTI-LOCK BRAKE SYSTEM) MODULE TERMINATING RESISTOR
    
    
    • Depower the SRS. REFER to: Supplemental Restraint System (SRS) Depowering and Repowering  .
    • Connect ABS Module C135 .
    • Measure:

      Positive Lead	Measurement / Action	Negative Lead
      C310B-59	Courtesy of FORD MOTOR COMPANY	C310B-60

    Is the resistance between 108 and 132 ohms? 

    Yes

    GO to  A7

    No

    GO to  A8

13. A7 CONFIRM THE RCM (RESTRAINTS CONTROL MODULE) FAULT
    
    
    NOTE: Make sure all SRS components and the RCM electrical connectors are connected before carrying out the self-test. If not, Diagnostic Trouble Codes (DTCs) will be recorded.
    • Disconnect RCM C310A and C310B (if not previously disconnected).
    • Prior to reconnecting any previously disconnected SRS component:
      • inspect connector(s) (including any inline connectors) for pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.
      • inspect wire harness for any damaged, pinched, cut or pierced wires.
      • inspect RCM C310A and C310B Connector Position Assurance (CPA) lever/lock for correct operation.
      • inspect ABS Module C135 for dirt, corrosion, water intrusion, pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.
      • repair any concerns found. Refer to Connector Repair Procedures for schematic and connector information.

    • Connect ABS Module C135 (if previously disconnected).
    • Connect RCM C310A and C310B (if not previously disconnected).
    • Repower the SRS. Do not prove out the SRS at this time. REFER to: Supplemental Restraint System (SRS) Depowering and Repowering  .
    • Ignition ON.
    • Using a diagnostic scan tool, perform RCM self-test.

    Was DTC U0028:88 retrieved on-demand during self-test? 

    Yes	CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new RCM. REFER to: Restraints Control Module (RCM)  . GO to  A10

    No	In the process of diagnosing the fault, the fault condition has become intermittent. Do not install any new SRS components at this time. Install SRS components only when directed to do so in the pinpoint test. GO to  A9

14. A8 CONFIRM THE ABS (ANTI-LOCK BRAKE SYSTEM) MODULE FAULT
    
    
    NOTE: Make sure all SRS components and the RCM electrical connectors are connected before carrying out the self-test. If not, Diagnostic Trouble Codes (DTCs) will be recorded.
    • Disconnect RCM C310A and C310B .
    • Prior to reconnecting any previously disconnected SRS component:
      • inspect connector(s) (including any inline connectors) for pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.
      • inspect wire harness for any damaged, pinched, cut or pierced wires.
      • inspect RCM C310A and C310B Connector Position Assurance (CPA) lever/lock for correct operation.
      • inspect ABS Module C135 for dirt, corrosion, water intrusion, pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.
      • repair any concerns found. Refer to Connector Repair Procedures for schematic and connector information.

    • Connect RCM C310A and C310B .
    • Connect ABS Module C135 (if previously disconnected).
    • Repower the SRS. Do not prove out the SRS at this time. REFER to: Supplemental Restraint System (SRS) Depowering and Repowering  .
    • Ignition ON.
    • Using a diagnostic scan tool, perform RCM self-test.

    Was DTC U0028:88 retrieved on-demand during self-test? 

    Yes	CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new ABS module. REFER to: HYDRAULIC CONTROL UNIT (HCU) . GO to  A10

    No	In the process of diagnosing the fault, the fault condition has become intermittent. Do not install any new SRS components at this time. Install SRS components only when directed to do so in the pinpoint test. GO to  A9

15. A9 CHECK FOR AN INTERMITTENT FAULT
    
    
    • Ignition OFF.
    • Depower the SRS. REFER to: Supplemental Restraint System (SRS) Depowering and Repowering  .
    • Disconnect ABS Module C135 .
    • Disconnect RCM C310A and C310B .
      • inspect connector(s) (including any inline connectors) for corrosion, pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.
      • inspect wire harness for any damaged, pinched, cut or pierced wires.
      • inspect RCM C310A and C310B Connector Position Assurance (CPA) lever/lock for correct operation.
      • inspect ABS Module C135 for dirt, corrosion, water intrusion, pushed-out, loose or spread terminals and loose or frayed wire connections at terminals.
      • repair any concerns found. Refer to Connector Repair Procedures for schematic and connector information.

    • Connect RCM C310A and C310B .
    • Connect ABS Module C135 .
    • Repower the SRS. Do not prove out the SRS at this time. REFER to: Supplemental Restraint System (SRS) Depowering and Repowering  .
    • Ignition ON.
    • Using a diagnostic scan tool, perform RCM self-test.

    Was DTC U0028:88 retrieved on-demand during self-test? 

    Yes

    This fault cannot be cleared until it is corrected and the DTC is no longer retrieved on-demand during self-test. CHECK for causes of the intermittent fault in the areas previously worked in, particularly the pins and terminals of any electrical connector that were disconnected. REPAIR any intermittent wiring, terminal or connector concerns found. Refer to Connector Repair Procedures for schematic and connector information. GO to  A10

    No	The fault is not present and cannot be recreated at this time. Do not install any new SRS components at this time. Install SRS components only when directed to do so in the pinpoint test. GO to  A10

16. A10 CHECK FOR ADDITIONAL RCM (RESTRAINTS CONTROL MODULE) AND ABS (ANTI-LOCK BRAKE SYSTEM) MODULE DIAGNOSTIC TROUBLE CODES (DTCS)
    
    
    WARNING: Turn the ignition OFF and wait one minute to deplete the backup power supply. Failure to follow this instruction may result in serious personal injury or death in the event of an accidental deployment.
    • Ignition OFF.
    • Depower the SRS. REFER to: Supplemental Restraint System (SRS) Depowering and Repowering  .
    • Reconnect all SRS components (if previously disconnected).
    • If previously directed to depower the SRS, repower the SRS. Do not prove out the SRS at this time. REFER to: Supplemental Restraint System (SRS) Depowering and Repowering  .
    • Ignition ON.
    • Using a diagnostic scan tool, perform RCM self-test.
    • Using a diagnostic scan tool, perform ABS Module self-test.

    Are any RCM and/or ABS module Diagnostic Trouble Codes (DTCs) retrieved on-demand during self-test? 

    Yes

    Do not clear any Diagnostic Trouble Codes (DTCs) until all Diagnostic Trouble Codes (DTCs) have been resolved. For ABS module Diagnostic Trouble Codes (DTCs), REFER to: ANTI-LOCK BRAKE SYSTEM (ABS) AND STABILITY CONTROL . For RCM Diagnostic Trouble Codes (DTCs), REFER to: Airbag Supplemental Restraint System (SRS) .

    No	CLEAR all Continuous Memory Diagnostic Trouble Codes (CMDTCs) in all modules. PROVE OUT the SRS. The repair is complete. RETURN the vehicle to the customer.