Instead of me typing for ages and drawing etc I've found a clip on youtube for you diode bit starts around 5 and half mins in look for how to test a transistor and diode ......by mjlorton that is the quickest way I can help you
Wits end now really. From todays exploits I have found that
1. I now have all 4 doors switches working.
2. The diode IS working correctly - after testing it like Discool advised
3. There is no power whatsoever to pins 1 & 16 of the alarm box.
So looking at this I then scratched me 'ead again, and went back to the MFU to check pin 5. I did this as looking at the diagram power exits pin 5, and should travel down to S261, where it then is split going to left front door switch, right rear & left rear, which it is doing now. It should (but isn't) also provide to Pin 16 Theft Alarm Unit & through the one way Tailgate diode to the rear tailgate & up to PIN 1 Theft Alarm Unit. Correct so far????
Now I have cut MFU Pin 5 at a reasonable working distance to check it. I then put the tester on the bit poking out of the MFU plug - 12V. Which if I'm correct I should expect to see????
I then put it on the other side of said cut wire and got 12V again??? Which I don't think I should be seeing, should I???
I been searching for while now for a new Multi-function unit, managed to get one from one of my dads old mates (he has a scrapyard) took the whole fuse box and white MFU off it. The truck it came off WAS running, until I butchered it, it was in because of dreaded tin worm. Everything electrical worked on it before I took off the box (got the alarm sounder too) now I've come home & removed my unit complete, powered everything up and STILL got ign & interior lights on . So it must be an earthing fault somewhere......But God knows where?????
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