Classic cars forum & vehicle restoration.

[Ray White]

Despite much head scratching, I am not yet able to get the ignition warning lamp to illuminate.

Having followed the advice from 'Stealth' with regard to fitting a relay with their Dynamator for positive earth cars, and wired in accordance with the diagrams, it is disappointing that I don't seem to be getting anywhere.

Note:
1) this relay does not have a diode
2) there is power getting to terminal 85 via the ignition switch.
3) As an alternator is now installed, the RF 95 control box has had the voltage regulation function disabled.

If my diagram needs alteration I would be glad of assistance. Please make suggestions that might help.

[ukdave2002]

Is the relay operating correctly? i.e. the bulb is earthed when the ignition is on.

[Ray White]

[Penguin45]

I don't see how the diagram can let the lamp work. Have a look at your thread from 2022 - HERE - which has an excellent description of what is meant to happen.

Chris.
_________________
'67 Wolseley MkI 18/85, '70 Austin MkII 1800 The Landcrab Forum.

[Ray White]

I would very much appreciate any advice as to how I can overcome what seems like an impossible hurdle for me.

For example, how is it I am getting 12 volts at BOTH dynamator terminals yet nothing at the lamp?

[ukdave2002]

Hi Ray, just a thought, if you are using the ignition lamp with the resistive winding, this could be problematic with an alternator?
If you have output from the 2 alternator terminals and the relay is grounding the lamp, there has to be 12v across the lamp unless there is a break in the wiring.

Dave

[Ray White]

Thanks Dave. I had another look at it and have identified a blown fuse. I have a wire from the ignition switch that goes to relay terminal 85 via terminal 3 on the disabled control box. It is there that a 25 amp fuse has blown.

I suspect I have messed up in this area.

[peter scott]

Hello Ray,

If the fuse doesn't blow with the 30 terminal disconnected from the relay then I would suspect that the lamp holder of your ignition warning lamp has a short circuit in it.

HTH

Peter
_________________
http://www.nostalgiatech.co.uk
1939 SS Jaguar 2 1/2 litre saloon

[Ray White]

[ukdave2002]

[Ray White]

[Ray White]

So, I have now isolated the circuit by removing other wires from the RF 95 control box and with just one wire from the ignition switch to the fuse and two wires from the other side of the fuse to the relay (30 & 85) I connected the battery and a 25 amp fuse blew again.

As the fuse blew when I connected the battery - and before I switched on the ignition - I assume the only route for power from the battery is via the starter solenoid through the alternator and into the relay.

I thought perhaps the relay might be at fault so I tested it with my multimeter. I got a reading of 95 OHMs - so assume O.K. There is no continuity between 30 and 87 so assume that's O.K. too.

One extra thing concerns the RF95 control box.
As mentioned, I have disabled the voltage regulation facility as it is included in the alternator. The TC wiring diagram shows an earth terminal between A3 and A4 . However, there is continuity between this earth and those two terminals. I assumed this was wrong and removed the earth wires and grounded them to the body. This time when I connected the battery the fuse held...but as soo as I turned on the ignition it blew again.

That was the last of my 25 amp fuses so I have ordered some more.

[Ray White]

I had difficulty in removing the large spade terminal from the dynamator such was the degree of corrosion. When it was removed and the battery connected, a 15 amp fuse held...even when the ignition was switched on.

I have been trying to remove the rust from the spade terminal... hoping that it will made a difference.





(I can't imagine what slitty eyed, dim witted prat thought is would be a good idea to make the spade terminals out of mild steel...saved a few pennies by not using brass did they?)

[ukdave2002]

Rust is conductive, was there any chance that the corrosion was shorting the output terminal to the alternator casing?

Failing that just perform a polarity (diode) test; set your multimeter to the lowest resistance range, check for conductivity between the alternator output terminal and the case, then reverse the meter leads and test again. It should conduct one way round but not the other, this will also indicate if the alternator is + or -ve earth.
If you get conductivity with both tests, then its lightly that either the surge protection diode that has shorted, or the internal regulator has failed, both repairable but will involve stripping the alternator down.

[Ray White]