1998 528i no power to Secondary Air Pump

[MJ & JJ]

Hi all, We have a 1998 528i that shows a DTC, I forget the #, but it points to the Secondary Air Pump. There is no power going to the pump. If I use an external 12V applied to the pump it runs. Does anyone know if the pump is supposed to run all the time? I didn't find any bad fuses, but I also didn't find any fuses labeled, Secondary Air Pump. Is it controlled by a relay? Thanks for your help! John

[Jeron]

It only comes on for a short while at startup. It has a relay and that is the next thing to check. You need a Bentley for the E39 or search the web for the relay location or try the main power distribution box and see if it is listed on the lid.

[Jeron]

Use this:
Electronic Shop Manual

Go to the Automotive section then select your car then Wiring Diagrams.

[MJ & JJ]

There is a valve/switch installed down stream of the scondary air pump. It is vacuum operated. I followed the vacuum line to a switch mounted between intake runners 1 & 2. I'm guessing that when the switch is activaed it lets vacuum pass through to the valve/switch downstream of the secondary air pump. The plug that goes into the switch did not have power when I checked it. Does anyone know when this switch is supposed to be activated? ( it may be called the Back Pressure Valve) And what activates it? We do have vacuum to the switch.

There was info on the switch:
7 22341.00
12V 98T145
1 742 712
Pierburg
PA6 GF30

We are still trying to find out more about how this whole system works.
We are also trying to identify which relay and/or fuse controls the secondary air pump.

Any info would be appreciated however small it might be.

Thanks!

[grafhky52]

the valve has nothing to do with the power to the pump. if no power, check the wires, if they are good, check the relay