GMC Troubleshooting Questions? Ask a Mechanic for Answers
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This usually means the EGR valve vacuum control solenoid has failed or vacuum line going to solenoid is leaking. Verify ignition feed to the three EGR solenoids, Pink wire. Test vacuum from the vacuum pump to the EGR valve vacuum control solenoid. Should have 19-20" vacuum with engine running. Check the EGR Valve Vacuum Control Solenoid for a ground pulse on the White wire from the ECM while the engine is running and EGR is commanded. The EGR valve vacuum control solenoid is normally closed. Check the EGR Vacuum Vent Solenoid control wire, White wire. This wire should be grounded by the ECM to block a vent path when the EGR is commanded ON. Here is also information from manual for code, let me know if you have questions. Thanks.
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