[s-cars] A new potential source of UrS current drain - a failed holding relay

[David Forgie]

One of the many functions of the holding relay inside the ECU is to provide power to the hot wire for 5 seconds
after the engine is turned off in order to burn off any crud that has accumulated since the engine has started
on this most recent trip.

For some time, a fellow on the S2Forum ("bilko0795") has been chasing an engine-off, battery-flattening, current draw
that he could not find on his ABY-powered S2 coupe.  Recently he posted up this:

"I have just gone to the garage to change the MAF over for a borrowed one. I placed my hand on the metal part of the MAF
 to hold it steady and burned my finger and thumb enough to leave a scald mark. Surely this can't be right the car has
 been in the garage over night and on trying to start it this morning it was dead so I left it until I'd change the 
MAF and then was going to charge the battery". 

He then checked for any live feed in the MAF connector (with the ignition off) and found that 2 pins that were
 permanently live, Pin 5/6 the power to the MAF (and injectors) and Pin 4/6 the burn-off power to the hot-wire
 in the MAF.  Not a good thing. 

Specific details (with diagrams and photos) are shown in this quattroworld post:

http://forums.quattroworld.com/s4s6/msgs/249356.phtml (follow the Holding Relay, MAF and ECU pin-out hyperlinks, as necessary)

Dave F.