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Hello new here and was hoping for some help. I have a code P0412 dealing with air injection relay switch A ??????? I changed a relay by the right rear engine compartment but not sure if that actually has anything to do with the air system now that I have done more research. Can anyone tell me if it does or not and what the relay is? Its mounted by the strut area and coolant jug etc. What do I need to be looking at or for when it comes to this P0412 code? I need to fix this asap before I go back to Afghanistan and leave this car with my wife broke. thanks

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P0412 Secondary Air Injection (AIR) Solenoid Relay Control Circuit Bank 1

This code is thrown when the air injection reactor (AIR) vacuum control solenoid voltage is not what the PCM commands. This us usually a wiring problem but can be a bad AIR vacuum control solenoid.

If the Check Engine light is not on, this code is not thrown consistently. If this error is detected consistently, the PCM will turn on the Check Engine light. Is the Check Engine light on? Are there any other codes?

This is the secondary AIR pump relay:

2002_STS_Secondary_AIR_Pump_Relay.png

(1) Secondary Air Injection (AIR) Pump Relay

This is the secondary AIR vacuum solenoid, not connected to the pump relay. The PMC is throwing P0412 because the voltages on this relay are incorrect.

2002_STS_AIR_Solenoid.png

(1) Control Vacuum to Front AIR Check Valve
(2) Control Vacuum to Rear AIR Check Valve
(3) AIR Vacuum Control Solenoid
(4) AIR Source Vacuum Hose

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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  • thanks for the pics and info. I replaced the relay. I am still getting the service engine soon light and code P0412. Could the problem be the air vacuum control solenoid? When I turn the key on I can hear a pump run for about 10 to 30 seconds and it sounds like it is coming from the rear possibly the passenger side. Hard to tell because I am the only one here to work on it so I cant be near the back of the car while someone else turns the key on and starts car. This is currently the only code that I have. The car had codes for oil pressure sensor, oil level switch, cam sensor, and the oxygen sensor but I replaced those and those codes are not coming back.

How can I check the air vacuum control solenoid? How do I check the air check valves?

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The air pump only runs for 30-40 seconds on cold start up. It should make some noise at the front of the car.

The service manual does mention to check the fuse after replacing the relay.

The only wiring diagram I can find right now is for California emissions. Look for the 'air pump' fuse in the underhood fuse block.

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The relay is not connected to P0412. I would check the wiring and connectors on the solenoid before I replaced it.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Jim...appears to be correct. After re-reading the post...the code seems to indicate a solenoid issue rather then a relay issue.

"The powertrain control module (PCM) uses output driver modules (ODMs) to control many functions of the engine and the transaxle. The ODMs supply the ground path for the PCM controlled device when the PCM commands the device ON. Each ODM is able to control several outputs. Unlike the quad driver modules (QDMs) used in earlier model years, the ODMs are able to diagnose each output circuit. The PCM monitors the ODMs for circuit conditions that are incorrect for the commanded state of the ODM. If the PCM detects an improper circuit condition in the ODM that controls the secondary air injection (AIR) solenoid, this diagnostic trouble code (DTC) will set."

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