Air Pump

apache31 · Post by **apache31** » 23 Jul 2011, 09:16

Please forgive my naivity. I am still learning my way around this car after owning it for the past six years.

Am I simply bridging the two wires in the harness (light green/dark green - blue/purple) with the diode?

It's not clear to me how to know I have the diode in the correct direction. I guess if it doesn't work one way, I can flip it around. Thanks for your help guys.

apache31 · Post by **apache31** » 23 Jul 2011, 15:42

Is this modification effected by the fact that, unlike the pics from the VS write-up, I have two ECUs...or whatever they are called? I have a center one and one toward the fender that are being used and that I removed to access the harness. Does this change the plan of attack at all?

Post by **JRL** » 23 Jul 2011, 16:25

ECU and a TCU which is your transmiossion control unit.
If you have an automatic, of course you have two

apache31 · Post by **apache31** » 23 Jul 2011, 17:05

Thank you for the explanation.
Do you know which pins to use for this? One write-up says A32 and A37 and another says A32 and B38.
This car is a 1997 850

Post by **erikv11** » 23 Jul 2011, 17:52

Use the Volvospeed writeup. It is the original, it is totally accurate, and very clear. I am not sure why the MVS link showed up in my post, I did not put it there. But note the VS link is mainly writte for Mortronic 4.4 cars (all S70s are 4.4, only some 850s are).

For your car, I was assuming it was Motronic 4.4 (the engine management system) but now that I have looked it up, it is either 4.3 or 4.4. You need to find out, to do so write down your VIN and go to this site:

http://new.volvocars.com/ownersdocs/199 ... n1997.html

Assuming the car is Motronic 4.4, then you need to bridge A32 to A37. I recommend bridging the wires, that is how I did it, but you can bridge the ECU if you want to.

If your car is 4.3 then you need to bridge the other pins but there may be other issues, I am less clear about the SAS delete on a 4.3 car.

You can tell the polarity (direction) of the diode by which side has the bar painted on it. The drawn diagram in the Volvospeed link shows the polarity pretty clearly.

apache31 · Post by **apache31** » 23 Jul 2011, 18:27

VIN = YV1LS5549V1360184

4 = w/o EGR w/air pump, w/OBDII, w/elec. control evap,
Motronic 4.4 w/Rulo., TLEV (55, 56)

Appears to be a Motronic 4.4

I bridged the ECU on A32 and A37.
Buttoned it up.
Entered my radio code.
Now the car won't start. Doesn't turn over at all. Any ideas?
Did I just screw myself or what?

apache31 · Post by **apache31** » 23 Jul 2011, 18:34

Am I supposed to disconnect something at the Air Pump as a final step before this works?
Went back and looked at all of the connections. Nothing appears damaged or wrong.
I left the positive side of the battery connected and disconnected the ground when I did this.
Would that cause an issue you think?

apache31 · Post by **apache31** » 23 Jul 2011, 20:05

UPDATE:

So far so good. No Check Engine Light so far. Will have 100 miles on it by tomorrow and will report back.
Thank you guys for ll of your help.

Post by **erikv11** » 23 Jul 2011, 21:47

Sounds great!

You do want to disconnect the electrical from the air pump. There is a plug from the air pump to a relay, it is mounted on the wall in front of and below the battery. You can trace the wire back to the air pump. Unplug it.

When you are certain there is no CEL (and there won't be!), then you can also remove the whole system if you want. Remove the SAS check valve and the plumbing (vacuum tubes) from the SAS valve to the solenoid mounted up on the radiator. Of course if you do this, you need to cover the holes in the exhaust and where the air pump connects to the intake. At the very least you can disconnect and remove the air pump. Here is a schematic of the whole system, you will recognize these parts under the hood:

EDIT: you MUST leave #12, the solenoid, in the car and connected. Leave the electrical hooked up to it. You don't need the vac lines that connect to it, but the ECU wants to see that solenoid to be happy.

apache31 · Post by **apache31** » 24 Jul 2011, 19:34

For now, can I just unplug the 2-wire plug at the pump and be good to go until I have time to do the rest?
In the drawing, that plug shows two wires coming off of it. On my car, that same plug only has one light blue wire coming off of it. It has room for two wires but there is only one coming out of it. I just unplugged it. There were two other smaller plugs I left intact. Do I need to unplug them as well?

Air Pump

Re: Air Pump