I’m getting along on the xk120 project, and would like someone to verify that I am on the right track for my alternator conversion. I did this years ago on my Mk2, but don’t remember all the details. There are some difference in details from past postings. I’ve posted the wiring diagram below.
Quite a few years ago, I installed a GM 1 wire in the 120 and used a heavy (?at least 6 gauge - BIG) wire for the alt to battery lead including a big single fuse on the bulkhead behind the glovebox - this block includes a digital voltmeter that one can see by opening the glovebox and to access the fuse. So, I’m thinking this is an adequate shunt to protect the ammeter from high current from the alternator - I don’t remember the alternator output (might be 80amp - ridiculous, I know), but it was not small. I’d like to keep the ammeter in the display, but could just bypass it. I converted an ammeter on the Mk2 with xj6 voltmeter guts, but I think this one would be harder to keep looking original.
In deleting the existing control box, this is what I am thinking to keep a working IGN light:
- Move the output lead (#37) from the ammeter to unused terminal A2, giving a fused circuit back to the panel through #36 and effectively bypassing the voltage regulator portion of the control.
-disconnect the F and D wires from the control box, bypassing the shunt part of the control. - splice the two segments of F wire #25 at the control box, leaving it connected to the IGN lamp, and hook the engine compartment end to the #1 terminal of the GM alternator.
- Use the #29 generator D wire to connect to #2 alternator terminal and move the control box end to the fuse box at wire #33 input. That should give battery voltage. I could jumper the #2 terminal to the alternator batt terminal instead, but some think that’s a shortcut.
Sound ok?
I also previously added an auxiliary fuse block behind the glovebox to run extra things like electric cooling fan and radio. I didn’t think it through very well, as I wired it hot, but it should really be switched. I don’t think it’s wise to put a lot of power though the ignition switch, so I’m thinking of adding a relay from the ignition switch to activate the new fuse box circuit. I was thinking of using the relay that I already have in place behind the glovebox that I installed for the fan circuit - the wire was adequately sized for 30 amps (fan ran great - not sure amperage) and already run from the inside bulkhead - I don’t think that relay is necessary. I would just run the cooling fan direct from the new fusebox on a 30 amp fuse. Any thoughts?
Xk120.pdf (173.0 KB)