2 replies to this topic

[Nytefog]

HI,

i;ve had a check engine light come on in my 850 wagon and had the code pulled. I found out it was a problem with the secondary air system (i can't remember exactly how it was worded). i do know that it has something to do with the air pump for emissions. How would i know if it was the actual air pump, the relay or the sas valve that is causing the issue? Sometimes when i turn the car off i can hear the air pump spooling down. I just don't want to spend 300 on a air pump and find out its something less expensive.

Thanks for any info

[pfeener]

I can give you some basics, but I only have first hand knowledge of the setup on an S70, which is slightly different. The ECU controls the secondary air system. It applies a ground to the air pump relay to pick the relay and turn on the pump. At the same time it also applies a ground to the check valve (SAS valve) relay to open the relay and apply maniford vacuum to the SAS valve to open it and allow air from the air pump into the exhaust.

You can check the air pump itself by removing it and applying 12V across the temrinal (be sure to observe proper polarity). On the S70 I pull the air pump relay and jump across the large contacts which will apply 12V to the air pump motor. I believe the air pump relay is mounted down by the air pump motor on the 850. It's probably a good idea to remove the air pump anyway to dump out any water which may have accumulated in the pump itself.

The air pump relay I usually check on the S70 by using an ohm meter to check for the proper resistance across the relay coil (lots of times there are shorted out and you will read zero ohms, I think the normal reading is around 10 ohms). If it reads correctly, I usually then swap it out with the main relay to check for proper operation.

Operation of the SAS valve is straight forward. An easy way to test; disconnect the air tube from the air pump at the SAS valve. Connect a short piece of hose to the SAS valve and try and blow through it. The SAS valve should be closed and you shouldn't be able to blow through it. If you can. it's stuck open. Next, apply (hand vacuum pump works best) vacuum to the SAS valve and try and blow through the hose again. You should be able to blow through the valve. If you can't it's stuck closed. You should also check out the SAS valve relay that controls the vacuum input to the SAS valve. Apply 12V across the relay (be sure to observe the correct polarity) and with the car running measure the vacuum at the end of the hose which plugs into the SAS valve. At idle you should read around 18 - 20 lbs of vacuum.

[Timwool]

On my 97 850 the air pump maybe going. if I take it to Autozone will they be able to read the codes that can confirm that it is the air pump that is turning on the CEL?

Also does anyone have the pin out diagram for the air pump relay I want to see if I jump it if it will start running.

Tim