LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1997 >> Forward Control 4.3 W, L35, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (Engine Controls - Tests W/Codes - 6.5L Diesel (P Series)) >> Diagnostic Trouble Codes >> DTC P1635 - Pcm 5-Volt Reference Low >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different variant/trim than selected.
  1. Perform Powertrain ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING article. Then go to next step.
  2. Install scan tool. Start engine or crank engine for 15 seconds if engine does not start. Check if DTC P1635 sets. If DTC P1635 sets, go to next step. If DTC P1635 does not set, go to step 5).
  3. Turn ignition off. Disconnect boost sensor connector. Turn ignition on, with engine off. Using DVOM, probe 5-volt reference circuit of boost sensor connector. If voltage is less than 4 volts, go to next step. If voltage is greater than 4 volts, go to step 6).
  4. Turn ignition off. Disconnect PCM connector. Using test light, probe boost sensor 5-volt reference circuit of PCM connector to battery voltage. If test light illuminates, go to step 7). If test light does not illuminate, go to step 8).
  5. DTC is intermittent. If no additional DTCs are set, see DIAGNOSTIC AIDS. If any additional DTCs are set, go to applicable DTC test.
  6. Replace boost sensor. After replacing sensor, go to step 9).
  7. Repair short to ground in 5-volt reference circuit. After repairs, go to step 9).
  8. Replace PCM. After replacing PCM, go to next step.
  9. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1635. Operate vehicle within the 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).
  10. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
scientia non olet · About LEMON Manuals