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?

[db9146]

LarryM,
Thanks for the great additional info!!! Saved it for reference.

Tonight I checked and:
- I have a 12V 2W Osram buld in the GEN socket
- it lights when I turn the ignition on
- it goes out a moment or two after the engine starts up
- I get 12.5V at the dash light
- 12.5V at the D+ female on the circuit board that the VR plugs into
- 12.5V at the D+ male spade on the circuit board that the plug from the Alt. connects to
- and 12.5 at the DF male spade on the circuit board that the plug from the Alt. connects to.

LarryM, you mentioned that the issue may be upstream in the wiring at the dash or ignition switch. If I'm getting 12V at the GEN bulb and D+ on the circuit board, wouldn't that indicate that the wiring between the circuit board, dash, and ignition switch is okay?

I understand that the next step is to try to measure the full alternator output by jumping DF to D+ but I really don't want to do this because the new engine is running individual throttle-bodies and MS3x. (CAUTION: Voltage is unregulated during this test and could damage sensitive electronics. {Balmar Alternator - Regulator Troubleshooting}). I think that means that I could kill my ECU.

It seems I really need to find another way to test the alternator.

NOTE: Before trying to perform the full field testing, I read that one common way to test modern alternators is to test for a magnetic field with a screwdriver once the switch is turned to the "on" position. However, I don't this will work on a Porsche -6 since it relies on the bulb to provide the resistance to "tickle" the alternator into charging.


(Man I don't want to drop the engine for this....)