[laso]

Hi everyone I have an F10 with an N20 engine. The car was taken from an electrician who tried to set up theft protection. He cut the white wire at the Power supply box and the check engine popped out on the dashboard. I have read errors and I have a "short curcuit 15N_3" error I checked the DME to Power supply box and there is no short circuit. Could the Power supply box be damaged?

[Node]

Care to provide an exact error code? There are several different short circuit codes related to that line.

[laso]

1B5402- Supply, terminal 15N_3: Short circuit to ground

[Node]

Do you use ISTA+ for error reading? For me ISTA+ gives "Supply, terminal 15N_3: Voltage problem" for 1B5402. Which is quite different from short circuit! Have you checked that CAS is properly able to switch on voltage to DME? You need to check that CAS properly sends voltage to pin 1 of DME main relay and there is proper ground on pin 2 of it (Both on connector Z11*1B). Then there should be no voltage on pins 6, 9, 12 of DME when car is sleeping and there should be 12V on there when ignition is on. Maybe that so called "electrician" also cut wire going from CAS to DME power supply relay? Or ground wire from above mentioned pin 2 of that relay to ground.

[laso]

Yes
I use ISTA Next 4.17.20

[Node]

So either that error text was changed in 4.18 or your ISTA applies some context to it using real car data. Anyway I think its worth checking that DME really gets 12V on those 3 pins.

If only one of them is missing I think DME will decide that there is a short circuit on it. Because why else can it be missing? And that would indicate that "electrician" worked on a car while it was powered and shorted that wire and a fuse inside DME power relay was blown. If ISTA wiring diagram is correct it may be possible to just check continuity between 15N<1, <2 and <3 outputs of the relay.

[laso]

Thank you very much. You were right on 15N_3 is missing power.
I undressed the Power relay and the fuse was just blown inside.