850 GLT 96 I've been back SAS'd

masonman · Post by **masonman** » 23 Feb 2010, 16:13

Does anyone know when the air pump comes on from a cold start?
I replaced the air pump, relay, solenoid and they all work. but not together. I don't know what to check next.

Thanks for the help!

Post by **jblackburn** » 23 Feb 2010, 16:25

Hrm...does your temperature gauge work right? e.g. does the car warm up quickly to the halfway mark and then STAY there? If it's never sending that signal, that would explain why it's not actvating

The ECT coolant temp sensor sends a signal to the ECU, which from a cold start will tell the air pump to activate. I mentioned on Brickboard that it will ONLY start the air pump after the car has been put into gear and has started to be driven. It will then run for ~2 minutes or so, and activates again with extended periods of idling in cold weather.

masonman · Post by **masonman** » 23 Feb 2010, 17:40

My temp gauge acts normal, will check in drive tommorrow.
Thanks!

masonman · Post by **masonman** » 24 Feb 2010, 17:07

Checked it in drive and the pump still didn't come on. Also, Checked ECT with MultiMeter and it was set to 20K , it read 2.64 @ 41F , does that seem right?

Post by **jblackburn** » 24 Feb 2010, 22:15

2640 ohms seems a bit low for 41 degrees, but it's possible the coolant was a bit warmer at the point that you tested it. I would expect it to be more between 4-6000 at that temperature. See if you can do that test again with the engine completely cold after sitting overnight and get a higher resistance reading from it.

But, seeing as you've replaced almost everything else, it might be time to pull out the ECU and clean any of the connectors that look corroded up, since it is the one responsible for sending out the signal that the air pump needs to activate in the first place.

masonman · Post by **masonman** » 01 Mar 2010, 08:28

7100 ohms @ 31F, Everything checks OK , still the pumps does not come on at a cold start

. Are there any other sensors that effect the pump? Interesting thing happened while doing checks. The coolant temp sensor was disconnected yet the temp gauge showed the temp rising. Am I not checking the right sensor?

jmichons · Post by **jmichons** » 23 Mar 2010, 18:16

jablackburn - Go Hokies!

My 98 S70 is having similar issues. Check valve opens about a minute after start but pump does not come on. I didn't try to drive and check it out yet. Pulled the ECM and checked wire to the pump relay. All seem to be good. If the drive doesn't work what else could I check? Is there a ground wire maybe?

Post by **jblackburn** » 23 Mar 2010, 20:47

It's always nice to see another Hokie fan out there

Hmm...I never did follow this one out.

Masonman, did you ever figure out your problem?

The control signal grounds back to the ECM, but I'm not sure where the pump motor itself grounds to...it may share the connection just under the battery.

I did, however, just realize that there is a fusible link in the cable. This may help both of you...if the pump was drawing too much current, it could have blown that fuse thus rendering the pump inoperable entirely.

secairinjfuse.pdf: (79.59 KiB) Downloaded 250 times

I wish I could find something about what exactly causes the pump to activate, but it seems most people either throw a check engine light, replace the pump and it goes away, or theirs works perfectly fine...not really in-between with troubleshooting it. If you can't figure it out, I'll take a look at my own for the connections & everything this weekend if I get a chance.

jmichons · Post by **jmichons** » 24 Mar 2010, 17:58

Hokie graduate actually. I can make the pump come on by jumpering the relay pins in the fuse box. So I know it is good. I replaced the check valve and know it is good. The pump just doesn't seem to come on when running the engine. I haven't yet tried to start driving, stop and listen to see if it is running.

Post by **jblackburn** » 24 Mar 2010, 18:09

Me too! I'm sure this is a familiar sight to you then:

Have you replaced the relay? The relays on these cars die like crazy, so that could also be an issue. Definitely try the driving check first - I notice the pump running sometimes when I move out and stop by the mailbox about 500 ft away in the mornings. The pinnacle of laziness, I know, but it's on the way out of my complex.