2005 Envoy 4.2 6 cyl

[Fox1]

Last spring I got some help here, I had a MIL on with a P0410 code (secondary air inj. sys failure). With Airjer's help I determined it was the pump and I replaced it and everything was fine.

A couple of days ago the MIL came on again with the same code. I have not checked the check valve I would have to remove it to apply voltage. So I removed the pump and applied 12 volts and it runs. Checked the voltage at the connector under the car and it's only 2.0 volts. I can not find a fuse or relay labeled AIR pump, smog pump or anything I recognize.

Any help would be appreciated.

[LightningBG]

Unfortunately, I cant be any help, but I'm interested in the answer. I just had the same code pop up on my Envoy yesterday. I will be watching with anticipation.

[LightningBG]

This is what I've found so far, which may or may not help.

Quote:

Symptoms

Possibly symptoms include:

* MIL illumination obviously

* Hesitation on acceleration

* Noise from a bad/stuck AIR pump

Causes

A code P0410 may mean that one or more of the following has happened:

* Water may have collected in the AIR pump or the vent solenoid and frozen or corroded the pump

* Blown AIR pump fuse due to freezing up

Possible Solutions

Note: There is a technical service bulletin (TSB) regarding this code for a number of GM models. The TSB calls for the replacement of the AIR pump and the installation of a new secondary injection hose. The TSB can be found on this ACDelco site.

Additionally, if you simply replace the AIR pump the problem may return again (and again). If you replace the pump, also clean out the hoses and replace the one-way check valve. If this is on a GM model that the TSB applies to, follow those instructions in the link above. In a few cases, people have put a small hole in the rubber cover on the pump which allows any water to drain out.

Also, please note that this may be covered under the emissions warranty on the vehicle. If your vehicle is out of bumper-to-bumper warranty, check if the emissions warranty is still valid!

* Replace the AIR pump AND one-way check valve

* Test and clean the AIR pump AND test and replace the one-way air check valve

* Replace the AIR pump inlet hose

* Replace the AIR pump fuse (found under the hood)

[Jeremy airjer W]

If you only have 2 volts going to the pump that I would pull the relay next to it and pop the plastic cover off of it and see if it is heavily corroded. It is not uncommon for them to fill up with water.

Is there 12 volts supplied to the relay when you unplug the connector?

[LightningBG]

Here is some more info I came across:

Just know that diagnosing this is time consuming since the "system" is only active for a few seconds on cold start.

for now:

1.) wait for your car to be "cold" or 4 hours. Disconnect the hose from check valve (located passenger side--the transmission dip stick is attached to the bolts that hold it to the block). Start the truck, you should hear a nasty sound for about 30 seconds to a minute. If you don't its your check valve.

1a.) If it is your check valve, you can try to clean it. Get some throttle body cleaner, remove the check valve spray thouroughly (I did it a couple of times to get all the carbon and rust out) and let dry reinstall and follow above instructions. If no go replace check valve

2.) wait for your car to be "cold" or 4 hours. remove the fattest hose from the underside of air intake hose (I think thats where it is, I have a CAI so Its hard to know where it is exactly OEM) and from the check valve. Have someone else start the truck. Feel the hoses, you should feel sucking and blowing (I can't remember which is supposed to blow / suck) If you don't feel anything then its the pump (maybe -- read further)

2a.) check fuses there are about 3 in the manual listed for air pump (if bad fuse replace and retest, make sure to check the fuses after to make sure that the pump isnt blowing fuses)

2b.) Locate the air pump its driver side mid car just behind the cross member for the frame. There are two wiring harnesess one that goes into the relay (grey box) and one that has two fat wires (thats the power plug for the pump.) disconnect that one, wait for cold start and start truck while having a multimeter attached set on DC mode. If you get a reading of 0 then replace the relay. if you get power 12-15 volts replace the motor.

3.) If both the check valve and the pump are testing out ok it could be a clogged hose.

[Fox1]

Well it ended up to be the solinoid. At least when I shorted out the solinoid I got a full 12.5 volts at the blower connection. The solinoid cost $41 with tax so if that is it I am happy. The test will be to see if the MIL comes back on after a few trips.

Thanks all for your help.