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Daniel Jones
Daniel Jones,
Category: Chevy
Satisfied Customers: 505
Experience:  GM A Tech at Straub Buick GMC
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99 s10 not getting 12v to egr where does it get it from like

Customer Question

99 s10 not getting 12v to egr where does it get it from like what pin on ecm? can i jump this in from battery or a key on source . getting code p0405
Submitted: 2 years ago.
Category: Chevy
Expert:  Daniel Jones replied 2 years ago.

Hello. Welcome to the site. Thanks for coming. I'm Dan J. I'm here to provide as much

information and insight as I can, to best answer your question.

Circuit Description

An exhaust gas recirculation (EGR) system is used in order to lower oxides of nitrogen (NOx) emission levels caused by high combustion temperatures. The EGR accomplishes this by feeding small amounts of exhaust gases back into the combustion chamber. When the air/fuel mixture is diluted with the exhaust gases, combustion temperatures are reduced.

A linear EGR valve is used on this system. The linear EGR valve is designed in order to accurately supply exhaust gases to the engine without the use of intake manifold vacuum. The valve controls exhaust flow going into the intake manifold from the exhaust manifold through an orifice with a control module controlled pintle valve. The control module commands the EGR by applying a 12 volt duty cycle to the EGR valve. This can be monitored on a scan tool as desired EGR position.

The control module can monitor the pintle position with the EGR pintle position signal. This sensor uses a variable resistor with a 5 volt reference, a signal circuit, and a ground. The signal circuit monitors changes in voltage on the variable resistor as the pintle moves.

The VCM will set a DTC P0405 if an unusually low pintle position signal voltage is detected for a calibrated period of time.

Customer: replied 2 years ago.
can i jump the 12v in from outside circuit as asked in first question ?
Expert:  Daniel Jones replied 2 years ago.

No, because the computer applies the 12v as a duty cycle to the EGR valve.

I can email you the complete diagnostic chart for that code or try to upload it.

Customer: replied 2 years ago.
ok yes e mail me that ,
looking at the diagram it looks to me that my 12 volt power would then be coming thru wire A ( red ) going to the blk connector on the ecm ? i am now also wondering is 12 volt always present with key on ? as i was told to check with just key on not running ?
Customer: replied 2 years ago.
pin 16 on the black connector cause maybe that is shorted and i could run a new wire
Expert:  Daniel Jones replied 2 years ago.

No, 12 volt is not always present.

Here is the diagnostic chart.

If you need more help, please use the "Reply" tab to continue our conversation - I'm happy to answer follow-up questions.
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Customer: replied 2 years ago.
I have 5 volts at pcm and egr on the rad wire
Expert:  Daniel Jones replied 2 years ago.

Do you have a scan tool to access the EGR data in the Vehicle Control Module(VCM)?

Expert:  Daniel Jones replied 2 years ago.
Hi, Just wanted to get an update on how you made out with vehicle.
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