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Home >> Chevrolet >> 1997 >> C3500 HD 7.4 J, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 3 (Engine Controls - Tests W/Codes - 6.5L) >> Diagnostic Trouble Codes >> DTC P1655 - EGR Solenoid Control Circuit >> 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 - 6.5L DIESEL article. Then go to next step.
  2. Install scan tool. Start and idle engine. Using scan tool, command EGR solenoid on and off. If actual EGR responds to scan tool commands, go to step 5). If actual EGR does not respond to scan tool commands, go to next step.
  3. Turn ignition off. Unplug PCM harness connector containing EGR solenoid control circuit. Turn ignition on. With DVOM connected to ground, set DVOM on 10-amp scale, check current from PCM connector EGR solenoid control circuit terminal. If current draw is less than .75 amp (but not zero), go to step 8). If current is not less than .75 amp (or is zero), go to next step.
  4. Turn ignition off. With PCM connector still unplugged, unplug EGR solenoid connector. Check resistance between ground and PCM connector EGR solenoid control circuit terminal. If resistance is infinite, go to step 13). If not, go to step 10).
  5. Turn ignition off. Disconnect EGR solenoid connector. Turn ignition on, with engine off. Connect test light between control circuit and ignition feed circuit of EGR solenoid connector. If test light illuminates, go to step 9). If test light does not illuminate, go to next step.
  6. Turn ignition on, with engine off. Using test light connected to ground, probe ignition feed circuit of EGR solenoid connector. If test light illuminates, go to next step. If test light does not illuminate, go to step 12).
  7. Turn ignition off. Reconnect EGR solenoid. Unplug PCM connector containing EGR solenoid control circuit. Turn ignition on. Using a fused jumper wire connected to ground, probe PCM connector EGR solenoid control circuit terminal. If solenoid clicks, go to step 11). If not, go to step 10).
  8. DTC is intermittent. If no additional DTCs are set, see DIAGNOSTIC AIDS. If any additional DTCs are set, go to applicable DTC test.
  9. Check for poor connections at EGR solenoid. Repair terminals as necessary. After repairs, go to step 15). If terminals are okay, go to step 13).
  10. Repair EGR solenoid control circuit. After repairs, go to step 15).
  11. Check for poor connection at EGR solenoid control terminal of PCM. Repair as necessary. After repairs, go to step 15). If connections are okay, go to step 14).
  12. Repair open in ignition feed circuit. After repairs, go to step 15).
  13. Replace EGR solenoid. After replacing solenoid, go to step 15).
  14. Replace PCM. After replacing PCM, go to next step.
  15. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P1655. 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).
  16. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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