gen diagnosis

[fusername]

so the baja bug (74 converted to generator) is acting up on the charging system. replaced the dinosaur of a battery in it, all was fine and dandy for two or three days. suddenly a generator light comes up. investigating the next day turns up a slightly melted DF wire at the reg, looks fine at the generator. turning the car on and revving it gets no charging voltage, zip at the gen. I polarized it and it spun merriliy. does this mean the reg is toast, or can a dead gen still spin up? all wires have good continuity.

i have a used reg, no idea if its good but I will swap it in, till then, pointers are welcome.

[fusername]

ok, going to try grounding DF and checking D+ voltage

[fusername]

flat zero volts on this test, what can make it so suddenly toast itself? anything I can do to fix or is it alt upgrade time? spins when i polarize it...

[Dale M.]

Go alternator......

Dale

[fusername]

Alt has plusses and negatives (get it) but there is a tight college budget involved, so if it doesn't need to happen, would like to avoid it. I will try polarizing it longer?

[fusername]

15 seconds of polarizing later and I got .36 volts out. Damn

[Dale M.]

15 seconds of polarizing later and I got .36 volts out. Damn

Here is diagnostic procedure for generator /regulator...

Generator/Regulator Test!

Disconnect all wires from Generator. (tag them so you get them back right)

Connect a test light ( 6 or 12 volt what ever is appropriate) on generator to the "D+" terminal ... Ground other side of light.

Ground "DF" or "Field" on generator.

Start engine... If light comes on and brightness increases as engine rpm comes up your REGULATOR is bad ( generator works ) Caution over revving engine to fast will cause light to burn out.

IF light stays dark ( does not light ) , check test setup again to be sure its right... If you rev engine up and light still does not light GENERATOR is bad.

People with experience using a VOLT-OHM meter could use the meter instead of light... look for VOLTAGE increase..

IF Generator fails, "maybe" you can clean armature and put in new "brushes" most likely it will be exercise in futility....

IF regulator is faulty, just replace it...

Personally I would dump the old school generator and go alternator, more cost now, but probably lest expense if future....

Dale

[fusername]

the failure was sudden and complete, so I'm gonna say its toast. maybe wrong reg was used? this is like 5 days after an engine swap. sad thing is brushes were new on that gen 3 years ago, covered and stored indoors and never driven, so they have like 20 miles on them.