Upgraded alternator now no spark? WTH?

[john 215]

Hi,

A lot of car's on the market had a resistor running in series to the bulb so if it failed then the alternator would still be excited.

Nowaday the alternator is controlled by, normaly the engine control unit, this will normaly only turn the alternator on ( via a signal wire, BSD line ) fully when under over-run or braking, slightly under cruise and off when accelerating. This is to save fuel, if you ever try to a turn alternator thats pumping out 80 + amps then you would know what drag it causes, you will need a big bar for sure!

The colour of the wire you are looking at should be brown and yellow.

Cheers John


LIVE LIFE A QUARTER OF A MILE AT A TIME!

1976 Speke FHC Beauty

1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6,ON THE ROAD NOW KICKING AR5E !!!!

[trekcarbonboy]

Ok just got around to testing those wires (been out mountain biking all day[:D]).
Yellow wire (supposed to be brown) constant power, brown/yellow no power with ignition on or off. Didn't check that light bulb yet.

Craig '75 2.0 FHC

[john 215]

Hi,

Constant live on your yellow wire ( as you say should be brown ) correct. Check that bulb and the live at the bulb, the printed circuits on the dash cluster can burn out so check that if no 12 volts present.

Cheers John


LIVE LIFE A QUARTER OF A MILE AT A TIME!

1976 Speke FHC Beauty

1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6,ON THE ROAD NOW KICKING AR5E !!!!

[trekcarbonboy]

Bulb is good, no power at the bulb. Please tell me there's another reason besides the printed circut board.

Craig '75 2.0 FHC

[HDRider]

Looks like all the warning lamps are feed from the same feed so if the other warning lamps work I would check the bulb holders and the condition of the printed circuit where the holder contacts touch.

The bulbs and gauges are all feed by a white wire from the ignition switch.

Make sure the bulb is working in all positions as well. I have seen the broken filament fall across the old connection and work sometimes when they are held just the right way.

Edward Hamer
Petaluma CA

[FI Spyder]

The printed circuit board gets it's power from some where. I would clean (with electric contact cleaner) all wire contact points on the circuit board. That included all pins/connector blocks, I also cleaned the bare copper parts of the circuit board with Brasso which brought them back to shiney copper (be sure to be careful with anything abrasive and clean off the cleaner afterwards). I even cleaned the wire pins of the bulbs and the twist holders they fit into. With all oxide off the contacts there is no electrical resistance in the circuit and you not only eliminate the possibility of said resistance from actually stopping the electricity completely and you end up with a nice brightly lit dash. Of course if there's a break in the circuit board you might try a little micro soldering with jumper wiring to by pass it. A little like brain surgery (or repairing an electronic typewriter circuit board.)[:p]



- - - - TR7 Spider - - - - - - - - 1978 Spitfire - - - - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - - Yellow TCT

[trekcarbonboy]

BTW my bulb is actually an LED. Not sure if that matters but I did put a good bulb in to check it and that didn't work either. Tested the circut directly to determine that it had no power. Will pull the instrument cluster out this weekend to inspect it closer.

Craig '75 2.0 FHC

[HDRider]

LED will not work as it only allows current flow in on direction.

Edward Hamer
Petaluma CA

[trekcarbonboy]

Ok finally got back around to sorting this out. I ran a jumper wire from the exciter wire on the alt to the battery just to see if the alt was actually working. As soon as I touched it to the battery my voltmeter instantly climbed to 14.5v, so clearly the alternator was working. So then I plugged the wires back together properly and went in the car to turn it off and noticed that the voltage guage was reading above halfway. Interesting! I went back to the battery and tested it and sure enough it was charging. Turned the car off to re-start and see if the ignition light would come on and sure enough it came right on. I have no idea what has changed from a week ago when I had no power coming from the dash to the alternator but now I have more then 9 volts coming from the dash with the key on. I guess the car just fixed itself!
Probably should look for a shoddy wire but for now I'm just glad to know it works.
Beautiful day today and tomorrow so I'll definately be out looking for the twisty roads![:D]

Craig '75 2.0 FHC