'68 Dash Warning Lights

Cougar Community Classic Cougar Maintenance Restoration and Repair
21

Update:

  • Regulator is well grounded against the fender apron
  • The wiring between the regulator and the alternator checks out OK
  • There is approximately 8 Ohms resistance between the ‘F’ terminal and ground when the car is not running
  • There is a healthy 12V at the 'A" terminal
  • When the car is running there is around 14.3V at the starter solenoid battery terminal
  • When the wire going to the ‘I’ terminal is manually shorted to ground, the AMPS light illuminates

Still no AMPS light when it should be on… :imp:

22

Brian,

Measure the resistance between the I terminal and ground on the alternator with the engine off and the key in ACC/ON position.

Coach Jack

23

OK, I am at my wits end with this and just about ready to chuck in the towel.

Rigged up a little test setup with the regulator out of the car to mimic what is happening with the engine not running:

When I turn on the supply to the 12V switched terminal, there is a full 12V drop across the 10 Ohm load resistor connected to the F terminal and no voltage drop across the indicator lamp.

If I disconnect the load resistor from the F terminal, the measured resistance between the I and F terminals is about 350 Ohms.

If I remove the lamp and apply 12V directly to the I terminal, measured resistance between the I and F terminals is approximately 1 Ohm.

If I disconnect the 12V supply from the A terminal, the I and F terminals are open circuit.

So the indicator lamp does not light under any circumstances: this does not make sense to me…

24

i assume you have rechecked the globe and tested it in its socket. I have had new globes that didn’t seat properly in the socket (cheap Chinese narva crap) … and you are using a bulb not an LED

25

Yes and yes. Bulb is an original GE unit and lights up just fine if I unplug the wire from the ‘I’ terminal of the regulator and ground it. At this stage I’ve pretty much eliminated the bulb and wiring as potential causes. All that leaves is the the alternator (not likely) and the regulator.

A replacement regulator was only $15 so I’ve ordered one and we’ll see if that fixes it. If not, I’m prepared to live without the warning light as I’m not going to chuck out a perfectly serviceable alternator…

26

Installed the new regulator this morning and the AMPS light now comes on with the key in RUN or ACC, so job done!

Good to see the world is still round…