Question about the AIR system

I have been reading multiple posts in here and over at the Trailblazer forum about the AIR system and the common problems we all seem to be having with them.

I have the dreaded Seconday Air Malf. code, I also was shown a PCM failure as well. I am wondering if I can fix this without going to the dealer. I would like to isolate the problem to determine if it is the pump, valve, relay, or something else entirely.

I have a couple of questions about this:

1. If I hear the whirring sound at cold startup, does that indicate that the pump is working properly?

2. Shortly before this happened, the gas cap would sometimes not seal properly, is it possible that the gas cap could trigger this problem?

3. I have located the pump, I believe since there are two things under there that look like they could be the pump. Where is the check valve? Is it under the hood or upwards in the line from the pump under the car?

4. What could trigger the PCM failure code along with the secondary air?

5. Moderately experienced in repair and hoping that this isn't over my head, let me know from those who have done it before??

Thanks.

Welcome to AF. First of all post any stored or live codes for more accurate answers.

The air switching valve

http://i83.photobucket.com/albums/j293/airjer/IMG00469-1.jpg

Yup, most common issue with this system.

In MN its almost a tie between the air pump and the valve. The first time I commanded the airpump on with the hose disconnected from the switching valve I took a shower, literally. I'm a little wiser after that and do all the turning on from inside the car! :O

The code was P0410 which said Secondary Air Intake Malfunction, also read a PCM failure with the Secondary Air code.

Replaced the gas cap and reset the ccomputer and it hasn't been back on, but I am sure it will return. THinking of replacing the valve next, what do you guys think?

You can check the valve by unplugging and using jumper wires to supply power and ground to the switch. You should hear an audible click if it is working. If the engine is running you would hear exhaust noise when it opened.

Thanks for the help guys. I have located the valve and plan on tackling it this weekend.

Is it possible that the resistor could be bad, which is triggering the code? I have disconnected the lines and drained out all the water. The light was off for about a week, then came back on. Just trying the least expensive thing first(resistor) before I try the valve($138).

Resistor?

sorry, not resistor, relay. The relay that is located close to the pump under the driver's side.

Also, when checking the valve, I know you can run a jumper from the battery to the valve itself. Which side of the plug is the hot and which is the ground??

If the pump is working the relay is fine. The relay has nothing to do with the valve. It doesn't matter what side is hot and what side is ground on the valve

I can hear the pump run on cold start up. High pitched wizzing sounds for about 20 seconds or so. Never could hear it as much before the check engine light came on.

I had read that the pump gets its ground from the computer, this is true? I had it hooked up to a diagnostic sysytem and I was told it was showing that the pump wasn't grounded. Ever heard of that?

So based on the fact that I hear the pump kick on and off at start up, it is safe to assume the the pump is working?

Thanks a ton for your help. Speedy help at that...

Disconnect the hose that goes to the switching valve. Turn the key on. Can you feel air coming out of the hose? If you do the pump is working.

I will test it and see what happens. Thanks again.

OK. Tested the pump and it is working as it should. Went and bought the check valve and installed it. The check engine light immediately went off and seemed to be ok. Drove it down the street and on the way back, at a stop sign, it almost went dead and the battery light suddenly came on. Now it idles very rough and if I turn on the heater or AC it idles up and down and will sometimes go dead.

Any ideas on what may be wrong now? Could it be O2 sensor that are unhappy since the check valve is functioning like it should be??

Please help...

Seemed to have fixed my own issue. Cleaned the throttle body and after mutiple starts, seems to have corrected the hard idle problem.