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John Culham

Ignition light on when ignition is off

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I am in the process of rewiring my TR250 with new RHD loom now that i have converted ithe car to RHD.

Lucas 16AC, alternator

When ignition is off ignition is on ( only 4 volts from ignition switch ), turn on ignition and ignition goes out and oil light comes on.

Replaced 4TR regulator ( 4 terminals ) but still the same.

Disconnect alternator still the same.

Remove the brown and red wire from the 4TR reg and ignition light never comes.

All wires removed from alternator its still the same

 

4TR black wire to - terminal, Brown and green wire to B+. 2 brown / yellow wires to + connection. Green / yellow to F

 

Every thing else work correctly.

 

 

As yet have not started the car as no exhaust or carbs fitted.

 

Any ideas ?

 

 

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John your description is a little unclear. Do we take it that with the ignition key switched off, the ignition warning lamp is on? Where are you measuring the 4 volts?

 

Your connections to the 4TR regulator do not tally with the published diagrams, which show:

 

Brown/red to B+

2 x Brown/yellow to +

Brown/green to F

Earth to -

 

 

There doesn't seem to be a green/yellow associated with the ignition - they go to the heater fan.

 

http://www.advanceautowire.com/tr2506.pdf

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You are correct brown/green is connected to F , typing error

4 volts to ignition warning lamp when ignition key switched off, light go off when ignition key switched is switched on,

 

The wiring drawing as you suggest is the one i have been using.

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Which end of the warning lamp is the 4V, the switch end (white) or the regulator end (brown/yellow) ? If you disconnect the lamp brown/yellow from the regulator does the light go off ?

 

Is it an original incandescent bulb or have you replaced it with an LED type?

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check the polarity positions on the regulator box , some reproduction regulators have the 4 terminals in a different order to the original ones.

graham

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Rob H


disconnect the lamp brown/yellow from the regulator and the light go off and does not come on when ignition is turned on.


original incandescent bulb fitted.


4 volt measured at white wire on ignition switch with key removed.



tr graham


You are correct the the F and neg terminals wire had to be swopped around for the new reg



Regards


John

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OK John - It looks as though the ignition bulb is getting a backwards voltage feed from the regulator (which should not be there), and is 'earthing' through something else which is also connected to the ignition switch - possibly the coil primary or the gauge voltage stabilizer and the oil pressure bulb ( which is why you see 4v there - the ignition bulb is dropping the rest ). The bulb goes out when you switch on the ignition because it now has +v on both sides.

 

First of all check that the black wire to the regulator '- ' terminal is a good solid earth.

Then I suggest you measure the voltage on the B+ terminal with everything connected and the ignition off. There should be no reading but I guess you will see 12v.

 

If there is an appreciable voltage then disconnect in turn the wires from the B+ terminal , F terminal and the alternator wire from the + terminal to see which one the feed is coming from.

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Rob

 

Run new earth from battery to reg with loom earth disconnected - terminal, no change.

No change with the following disconnected :- Coil, oil pressure switch, petrol pump, reverse light switch,windscreen washer pump, stop light switch, flasher unit, and wiper motor wires

Both the ignition and oil light work correctly with the brown and red wire removed from the reg

Ignition light stays with the brown and yellow wire removed from the alternator, goes out when removed from reg.

B+ at reg is always live ( brown and red wire ) as connected battery live at starter solenoid

 

Just notice oil light glows now that it has been removed from rev counter

 

Regards

John

 

Regards

 

John

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I think that just confirms what I said that the 'earth' for the ignition lamp is coming through the oil light (but that is not a fault - its a symptom). It also looks as though the stray voltage is coming through the regulator from the 'B+' connection. That should not happen as the B+ terminal is just there to monitor the battery voltage and there are resistors and other components in the way inside the regulator which should prevent enough current getting to the '+' terminal to light the bulb. The other possible route is from the brown/green wire to the F terminal - did you try removing just that one?

 

I hate to say this but its beginning to look possible that you have a duff regulator. I know you said you tried another and the fault stayed, so perhaps two duff regulators.........

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Rob

 

Ignition light stays on when brown and green wire removed from reg.

 

Will send reg back to Rimmers and ask for a replacement.

 

Thanks for your help.

 

Is there any way the reg can be bench tested using a multi meter ?

 

Regards

John

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This is the diagram of what is (should be ) inside the regulator. Short of making a test rig to simulate the alternator I don't think there is much you can do with a simple meter. (Note the + terminal is shown as B on this diagram). There should be a resistance of at least 1.34k Ohms between the B+ and + terminals measured in either direction.

 

 

post-7865-0-07348600-1471128969_thumb.jpg

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There are two types of 4TR- a three-terminal one and a four-terminal one The one you have looks like a three-pin one which has been made to look like an older four-pin by the addition of an extra functionless terminal.

The internal drawing I posted is supposed to be the original Lucas arrangement for four-terminal regulator- aftermarket ones will probably be different in the components used and the layout BUT the two terminals must not be shorted together if it is to function as per the drawing you are following.

 

 

Making the right connections depends on what alternator you have. Assuming your alternator has the field diode 'trio' fitted, I think the 4TR you have should work as a three-terminal one if you just leave the brown/red wire disconnected at both ends. i.e. no connection to the B+ terminal.

 

post-7865-0-57225900-1471190428_thumb.jpg

Edited by RobH

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Rod

 

I agree.

 

took many hours of checking / testing but all work as it should, I just hope it work correctly when the engine is running.

I am going to have the alternator checked just to make sure is is not faulty.

 

Thank you very much of your time and help.

 

Regards

John

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