Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2006SUBURBAN C1500, 5.3 ZREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 201 (CHARGING SYSTEM)DIAGNOSTIC TESTSDTC P0622: IMPROPER PULSE WIDTH MODULATED SIGNAL (GASOLINE ENGINE)DIAGNOSTIC PROCEDURE
2006 Chevrolet Suburban C1500, 5.3 Z
Diagnostic Procedure
2006 Chevrolet Suburban C1500, 5.3 ZSECTION Diagnostic Procedure
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- If diagnostic system check was not performed, perform ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM. If diagnostic system check was performed, go to next step.
- Connect scan tool to Data Link Connector (DLC). See COMPONENT LOCATIONS . Start the engine. With scan tool, observe the GEN-F Terminal parameter in the engine data list. If the scan tool indicates that the GEN-F Terminal, problem is intermittent. Check wiring and connections. If parameter is not 5-95 percent, go to next step.
- Turn ON the ignition, leaving the engine OFF. Connect a test lamp to battery positive voltage and repeatedly probe the generator field duty cycle signal circuit or F-Terminal in the harness connector while monitoring the Generator F-Terminal Signal on the scan tool. If the Generator F-Terminal Signal display is affected, go to step 5 . If the Generator F-Terminal Signal display is not affected, go to next step.
- Test Gray wire for a short or an open between generator harness connector terminal "C" and PCM harness connector C2 terminal No. 52. See WIRING DIAGRAMS . If problem exists, repair as necessary. After repair, go to step 8 . If problem does not exist, go to step 6 .
- Inspect generator harness connector for poor connections. If problem exists, repair as necessary. After repair, go to step 8 . If problem does not exist, perform TEST A: CHARGING SYSTEM TEST under SYSTEM TESTS.
- Inspect PCM harness connector for poor connections. If problem exists, repair as necessary. After repair, go to step 8 . If problem does not exist, go to next step.
- Replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article in ENGINE PERFORMANCE. Program PCM. After repair, go to next step.
- Review and record scan tool fail records data. Using scan tool, clear DTC's. Start engine. Using scan tool, observe specific DTC Information for DTC P0622 until test runs. If scan tool indicates DTC P0622 passed this ignition, system is okay. If scan tool indicates DTC P0622 failed this ignition, go to step 2 .
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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.