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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 69 (Automatic Transmission Diagnosis - 4L80-E (Diesel)) >> Diagnostic Tests >> DTC P0719: Brake Switch Circuit - Low Input >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 GMC Cab & Chassis Sierra and 2002 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the diagnostic system check? If so, go to next step. If not, see DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM.
  2. Install a scan tool. Turn ignition on, engine off. Before clearing the DTC, use the scan tool to record the freeze frame and failure records. Using the CLEAR INFO function erases the failure records from the PCM. Record the DTC failure records. Clear the DTC. Select the TCC BRAKE SWITCH on the scan tool. Disconnect the stoplamp switch connector. Connect a test light from stoplamp switch connector terminal "E" (140) to a known good ground. Does the test light illuminate? If so, go to next step. If not, go to step  4 .
  3. Install a fused jumper wire from stoplamp switch connector terminal "E" (140) to terminal "F" (17). Did the scan tool TCC BRAKE SWITCH status change from OPEN to CLOSED? If so, go to step  10 . If not, go to step  12 .
  4. Remove the Stop/Hazard fuse. Inspect the Stop/Hazard fuse for an open. Is the fuse open? If so, go to next step. If not, go to step  11 .
  5. Replace the Stop/Hazard fuse. Does the replacement fuse open immediately? If so, go to next step. If not, go to step  7 .
  6. Test the stoplamp switch battery positive voltage circuit (140) for a short to ground between the power distribution block and the stoplamp switch. Did you find and correct the condition? If so, go to step  14 .
  7. Connect the stoplamp switch connector. Apply the brake pedal. Does the fuse open immediately? If so, go to next step. If not, see DIAGNOSTIC AIDS  .
  8. Disconnect the PCM connector C2. Replace the brake switch fuse. Apply the brake pedal. Does the fuse open immediately? If so, go to next step. If not, go to step  13 .
  9. Test the stoplamp switch signal circuit (17) for a short to ground between the PCM connector C2 terminal B10 and the stoplamp switch connector. Did you find and correct the condition? If so, go to step  14 .
  10. Replace the stoplamp switch. See STOPLAMP SWITCH  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to step  14 .
  11. Test the stoplamp switch battery positive voltage circuit (140) for an open between the power distribution block and the stoplamp switch connector. Did you find and correct the condition? If so, go to step  14 .
  12. Test the stoplamp switch signal circuit (17) for an open between the PCM connector C2 terminal B10 and the stoplamp switch connector. Did you find and correct the condition? If so, go to step  14 . If not, go to next step.
  13. Replace the PCM. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Did you complete the replacement? If so, go to next step.
  14. Perform the following procedure to verify your repair:
    • Select DTC.
    • Select CLEAR INFO.
    • With ignition on, engine off.
    • Apply the brake pedal.
    • The scan tool TCC BRAKE SWITCH STATUS must indicate CLOSED (12 volts) for 2 seconds.
    • Select SPECIFIC DTC.
    • Enter DTC P0719.

    Has the test run and passed? If so, system is okay. If not, go to step  1 .

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