A friend has asked me to look at his 2001 Lexus IS200 that he thinks has a charging/battery issue. I don't think they sell the IS200 in the USA but they do sell the IS300. I've checked the charging system diagrams for both and the alternator wiring is basically identical.
(Diagram has been uploaded, I hope it appears!)
If you look at pin 1 of connector B at the alternator, that wire goes to the Engine ECU. There is no detail on the diagram what this wire does - e.g is the wire used to monitor battery/charging voltage by the ECU (i.e there should be battery voltage on the wire with the engine running) or is it a control wire from the ECU to adjust the level of charging by the alternator?
I checked the Lexus technical information website but couldn't find a 'description and operation' section on the charging system.
Could anyone tell me what this wire does and what should be seen on the wire on a normally working system?