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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 4.3 W, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROL SYSTEM - TESTS W/CODES - DTC P0205-P0351DTC P0335DTC P0335: CRANKSHAFT POSITION (CKP) SENSOR CIRCUIT (4.8L, 5.3L & 6.0L "C" & "K" SERIES)DIAGNOSTIC PROCEDURES
1999 GMC Forward Control 4.3 W, Standard

Diagnostic Procedures

1999 GMC Forward Control 4.3 W, StandardSECTION Diagnostic Procedures
  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
  2. If engine starts and runs, go to next step. If engine does not start and run, go to step  4.
  3. Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function then enter this DTC. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS .
    CAUTION: Before proceeding, remove ignition and fuel feed circuit fuses to prevent personal injury from engine rotation, sparks or excessive engine fueling.
  4. Disconnect CKP sensor harness connector. Turn ignition on, with engine off. Connect a test light between ground and CKP sensor ignition feed circuit PCM side of CKP sensor harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  8.
  5. Connect test light between CKP sensor harness connector ignition feed and ground circuits. If test light illuminates, go to next step. If test light does not illuminate, go to step  9.
  6. Momentarily connect test light between CKP sensor signal circuit and CKP sensor ignition feed circuit. If fuel pump operates when ignition voltage was applied to CKP sensor signal circuit, go to step  11. If fuel pump does not operate, go to next step.
  7. Reconnect CKP sensor connector. Turn ignition off. Disconnect PCM harness connector. Using Brown jumper from Connector Kit (J-35616-A) and DVOM set to 40 VAC scale, check voltage (front probe) to signal circuit. If voltage reading is 4-6 volts, go to step  15. If voltage reading is not as specified, go to step  10.
  8. Check for open or short in CKP sensor ignition feed circuit. Repair as necessary. After repairs, go to step  16. If circuit is okay, go to step  15.
  9. Check for open or short in CKP sensor ground circuit. Repair as necessary. After repairs, go to step  16. If circuit is okay, go to step  15.
  10. Check for CKP sensor signal circuit for open, short to ground or short to voltage. Repair as necessary. After repairs, go to step  16. If circuit is okay, go to next step.
  11. Visually inspect CKP sensor for physical damage, loose or improper installation, wiring routed too close to secondary ignition components or poor connections/terminal contact at sensor or PCM. Repair as necessary. After repairs, go to step  16. If components and circuits are okay, go to next step.
  12. Visually inspect CKP sensor reluctor wheel for damage. Replace or repair reluctor wheel as necessary. After repairs, go to step  16. If reluctor wheel is okay, go to next step.
  13. Check for poor connections/terminal at CKP sensor or for proper reluctor wheel installation. Repair as necessary. After repairs, go to step  16.
  14. Replace CKP sensor. After replacing sensor, go to step  16.
  15. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  16. Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step  2.
  17. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.