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.
Circuit/System Testing
2006 Chevrolet Suburban K2500, 6.0 USECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
If the interior backlighting is malfunctioning, refer to Interior Backlighting Malfunction (w/AN3)
or Interior Backlighting Malfunction (w/o AN3)
before performing this diagnostic.
- Ignition OFF, disconnect the harness connector at the PTO switch.
- Connect a test lamp between LED dimming supply circuit terminal 7 and ground.
- Ignition OFF, turn the headlamps ON and OFF. The test lamp should turn ON and OFF accordingly with the headlamp switch.
- If the test lamp is always ON, test the LED dimming supply circuit for a short to voltage.
- If the test lamp is always OFF, test the LED dimming supply circuit for a short to ground or an open/high resistance.
- Ignition ON, verify that a test lamp does not illuminate between the PTO switch indicator control circuit terminal 8 and ground.
- If the test lamp illuminates, test the PTO switch indicator control circuit for a short to voltage. If the circuit tests normal, test or replace the PTO module.
- Ignition OFF, PTO OFF, verify that a test lamp does not illuminate between the PTO switch indicator control circuit and B+.
- If the test lamp illuminates, test the PTO switch indicator control circuit for a short to ground. If the circuit tests normal, test or replace the PTO module.
- Ignition OFF, disconnect the harness connector at the PTO module.
- Ignition OFF, test for less than 1.0 ohm of resistance on the PTO switch indicator control circuit between the PTO switch terminal 8 and the PTO module terminal 9.
- If greater than the specified range, test the PTO switch indicator control circuit for an open/high resistance.
- If all circuits test normal, test or replace the PTO switch.
RENDER: 1.0x
NO RELATED
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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.