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.
4.3L C, G, K, & P Series W/4L80-E Transmission
PCM controls a solenoid regulating vacuum to the EGR valve. The normally closed solenoid prevents vacuum from passing until it is energized by PCM. A properly operating EGR will directly affect fuel integrator counts. With EGR valve open, integrator counts will be less than without EGR operation. If monitored integrator counts do not change with EGR commanded, Code 32 will set.
- When test terminal "B" of the ALDL connector is grounded, EGR solenoid should be energized, allowing vacuum to the EGR valve. Vacuum should hold.
- When jumper wire is removed from terminal "B", vacuum to the EGR valve should bleed through a vent in the solenoid and EGR valve should close. Vacuum gauge may or may not bleed off vacuum, however, this does not indicate a problem.
- Determines if fault lies in electrical control part of the system, connector or solenoid.
- This system uses a negative backpressure EGR valve. Valve should hold vacuum with engine off.
- When engine is started, backpressure should cause vacuum to bleed off and valve should fully close.
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.