Pinpoint Test H: DTC C1187: Brake Fluid Level Input Circuit Open

Test Step 

1. H1 CHECK ABS MODULE OPERATION 
   • Disconnect: Brake Fluid Level Switch C124.
   • Connect a jumper wire between the brake fluid level switch C124 pin 2, circuit 512 (TN/LG), harness side and the brake fluid level switch C124 pin 3, circuit 531 (DG/YE), harness side.
     Fig 1: Connecting Jumper Wire Between Brake Fluid Level Switch

     Courtesy of FORD MOTOR CO.
   • Connect the diagnostic tool.
   • Key in ON position.
   • Enter the following diagnostic mode on the diagnostic tool: ABS Module Self-Test.
   • Clear the DTCS and repeat the self-test with the brake pedal not applied. Retrieve the DTCs.
   • Is DTC C1187 retrieved again? 

   Result / Action to Take 

   1. Yes  : GO to H2.
   2. No  : INSTALL a new brake fluid reservoir. REFER to BRAKE SYSTEM-GENERAL INFORMATION . CLEAR the DTCs and REPEAT the self-test with the brake pedal not applied.
2. H2 CHECK CIRCUIT 512 (TN/LG) AND 531 (DG/YE) FOR AN OPEN OR A SHORT TO GROUND 
   • Key in OFF position.
   • Disconnect: ABS Module C135.
   • Measure the resistance between the ABS module and the brake fluid level switch; and between the brake fluid level switch and ground as follows:
     RESISTANCE
     
     

     Brake Fluid Level Switch	ABS Module	Circuit
     C124 pin 2	C135 pin 25	512 (TN/LG)
     C124 pin 3	C135 pin 23	531 (DG/YE)

     Fig 2: Measuring Resistance Between ABS Module And Brake Fluid Level Switch

     Courtesy of FORD MOTOR CO.
   • Is the resistance less than 5 ohms between the ABS module and the brake fluid level switch and greater than 10,000 ohms between the brake fluid level switch and ground? 
   1. Yes  : GO to H3.
   2. No  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test with the brake pedal not applied.
3. H3 CHECK FOR CORRECT ABS MODULE OPERATION 
   • Disconnect all ABS connectors.
   • Check for:
     • corrosion
     • pushed-out pins
   • Connect all ABS connectors and make sure they seat 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 ANTI-LOCK BRAKE SYSTEM (ABS) MODULE . TEST the system for normal operation.
   2. No  : The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test with the brake pedal not applied.