Charging question on a 914-6 Options

[db9146]

Well, I have made a temporary conversion of my -6, inserting a rebuilt 2.7S with ITBs, MS3, and distributorless ignition in place of the tired 2.0L. Before putting the engine in, I decided it best to install a new alternator along with a new engine/alternator wiring harness.

The alternator is for a 1965-1977 911 2.0-2.7 that uses an external VR.


and here's the new wiring including a new ground strap to the engine case.


The large red cable goes to the starter, the smaller red wire is D+, the black is DF, and brown is D-.

I thought the problem might be the battery because of its age but when I checked the output of the charging system at the battery, there was none. I replaced some of the dash lights with LEDs but made sure not to replace the GEN warning light, which is not coming on despite the alternator not charging.

Should I next pull the D+, DF, and D- plug and check for alternator output across DF and D+ momentarily?

If there is output, what then?

If not, what's next?

[larryM]

you wrote above: "the GEN warning light, ... is not coming ON"

if it is never ON, then you are not getting 12v field exciter current to the regulator

- your initial problem is to get juice to & thru that bulb & to the VR so that the VR can energize the alt field

"2-3 watt bulb is enough for normal alternator excitation." Scroll to page 20 of this > https://woodmizer.com/us/portals/0/docs/743...9c0c8e77ef1.pdf

iGN ON (not running) - measure the voltage on the (blue) wire which should be attached to that bulb - where it connects to your relay panel - so you know if you have current twixt the ign sw & thru the bulb to the next potential roadblock item (the panel) - if ya got 12v there,

if you ground that wire the bulb should light, which tells ya circuit is active to that point

then see if you have 12v at the VR plug (color of wire is different after it leaves the panel) - if ya got 12v all the way to the VR, (and you already tried a new VR) then your alt field is not energizing, thus no output

you should read 12V at field wire DF - if you then jumper DF to D+ with a fused jumper, (engine running) you should get full alternator output - if no 12V at VR DF with ign on, then your problem is upstream, either a bad regulator or bad wiring to dash & ign

OR - possible bad alt or incorrectly wired at the back of alt

here are pics of some notes from back in 2009-10 when i had a similar problem (difference: my -6gt- never had a relay panel)