Hi all,

 

Looking further into my speedometer issue... Ive realised there was a single black and white wire that went to pin 88 on the ECU (on the the smaller ecu connector). 

 

Looking on elsawin, this seems to go to SB29 which is a 5a fuse, and then to A33 which is the positive connection (73) in wiring harness behind dash panel.

 

Would anyone happen to know what this pin is for on the ECU... 

 

 

Should probably mention its a 2004 vrs with ASZ engine.

Have a look at the 'basic equipment' section of the circuits, particularly the ignition switch.  Terminal 75 is one of the outputs of the switch at pin 2, going to the load reduction relay (J59) coil, the onboard supply control unit (J519), and anything commoned to point A33 in the circuits. It seems to only be powered direct from the ignition switch at the first position of clockwise rotation.

 

It's not obvious to me just now what's going on with this.

J519 can presumably maintain/control this A33 rail independently of the ignition switch.

The connection of this to the engine ECU looks a bit like a 'wake up and get ready' signal?

 

Looking forward to understanding this better!