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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15181
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I have a 2007 Chevrolet Trailblazer 4.2l the secondary air

Customer Question

I have a 2007 Chevrolet Trailblazer 4.2l the secondary air pump won't come on. I replaced the air pump , air solenoid, relay to the pump and relay to the air solenoid. I jumped the connecters at the pump relay, and the pump came on. Everything has power at the pump relay but the PCM is not commanding the relay to ground through the brown wire. I replaced the PCM and the pump still didn't come on. I didn't want to pay for a crankshaft relearn so I returned the PCM and put the old PCM back in. The temperature sending unit is reading the right temperature with my code reader. The O2 sensors are oscillating twice a second 1 volt. Any help would be appreciated.
Submitted: 12 months ago.
Category: Chevy
Expert:  Roy replied 12 months ago.

good evening my name is ***** ***** I will assist

what was the temp of the motor when you were testing??

are you using a scan tool to command the pump on???

Roy

Customer: replied 12 months ago.
It was cold and I can't command the pump on with my scan tool
Expert:  Roy replied 12 months ago.

ok, if you ground the brown wire at the relay. will the pump come on???

Roy

Customer: replied 12 months ago.
I haven't tried that yet.
Expert:  Roy replied 12 months ago.

try that next. if it does, then there is a wiring issue. if it does then the relay is not operating..

Roy

Customer: replied 12 months ago.
I grounded the relay at the brown wire and the air pump worked.

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