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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis >> External Pages >> Different car >> Section 26 (Engine Controls Self-Diagnostics - 5.0L & 5.7L) >> Diagnostic Tests >> DTC P1639: 5-Volt Reference 2 Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2001 GMC Savana, 2001 Chevrolet RV Cutaway, 2001 Chevrolet Cutaway, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK . After performing powertrain diagnostic system check, go to next step.
  2. Observe FREEZE FRAME/FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria or as close to FREEZE FRAME/FAILURE RECORDS data as possible. If DTC failed this ignition cycle, go to next step. If DTC did not fail this ignition cycle, see INTERMITTENT TROUBLE CODE DETERMINATION  under ON-BOARD DIAGNOSTICS under SELF-DIAGNOSTIC SYSTEM.
  3. Visually and physically inspect PCM and engine grounds. Ensure grounds are clean and secure. If problem was found, repair as necessary. After repairs, go to step  13. If problem was not found, go to next step.
  4. Turn ignition off. Disconnect FTP sensor connector. FTP sensor is located in fuel tank sender. Connect a DVOM between FTP sensor connector terminal "C" (Gray wire) and ground. See Figure. Turn ignition on, engine off. If voltage is about 5 volts, go to step  11. If voltage is not about 5 volts, go to next step.
  5. If voltage is more than 5 volts, go to next step. If voltage is not more than 5 volts, go to step  7.
  6. Turn ignition off. Disconnect PCM connectors. Check Gray wire between FTP sensor and PCM for short to voltage. If problem was found, repair as necessary. After repairs, go to step  13. If problem was not found, go to step  12.
    7. NOTE: Ignition must be turned off for this test.
  7. Turn ignition off. Disconnect PCM connectors. Using a DVOM, check for continuity between FTP connector terminals "A" (Black wire) and "C" (Gray wire). If continuity exists, go to step  9. If continuity does not exist, go to next step.
  8. Leave ignition off. Leave PCM disconnected. Using a DVOM, check for continuity between FTP sensor connector terminal "C" (Gray wire) and ground. If continuity exists, go next step. If continuity does not exist, go to step  12.
  9. Repair short to chassis ground or short to Black wire in Gray wire between FTP sensor and PCM. After repairs. go to step  13.
  10. Check Dark Green wire between FTP sensor and PCM for short to voltage. If problem was found, repair as necessary. After repairs, go to step  13. If problem was not found, go to next step.
  11. Replace FTP Sensor. After repairs, go to step  13.
  12. Replace PCM. Program PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  13. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Start engine. Operate vehicle within code enable criteria. If DTC runs and passes, go to next step. If DTC does not run and pass, go to step  2.
  14. Using scan tool, observe stored information. If scan tool displays any DTCs that have not been diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If scan tool does not display any DTCs, system is okay.
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