Secondary Air Pump in 1995 530i

[Walter Cruden <cruden@xxxxxxxxxxxxx>]

The purple most inboard relay in the electronics box appears to control the Secondary Air Pump in a
1995 530i.  What is the purpose of the Secondary Air Pump and what is the Motronic 3.3 strategy in
activating/deactivating the Secondary Air Pump?

BTW, the white relay in electronics box is the Motronic Main relay and the orange fender most relay is
the fuel pump relay.  The fuel pump relay has four male connectors.  The Motronic Main relay has an
extra 87 output male connector.  And the Secondary Air Pump relay has an 87a output male connector.
87 and 87a are opposites of the toggle meaning when one is on the other is off.  With the coil
deactivated, 30 is NC with 87a.  With the coil activated 87a opens from 30, and 87 which is NO with 30
now becomes closed.

The schematic in the repair manual shows 87 NC with 87a placing ground to both inputs to the Secondary
Air Pump.  With the coil activated, 87 which is shown as NO with 30, closes with 30 supplying power to
the Secondary Air Pump.

The difference in the manual schematic to the schematic on the relay would normally suggest I am
looking at a different relay.  But the component locations in the manual shows the Secondary Air Pump
relay in the electronics box for 1994 but is silent for 1995 though a Secondary Air Pump is listed for
1995.  Also the more complex relay to looping ground to both sides of the Secondary Air Pump motor in
the manual schematic doesn't make sense to me.

All illumination gratefully appreciated.

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