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Ignition lite on

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roofman

roofman

Jedi Knight
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Just installed my newly rebuilt lucas alternator and now my ignition light stays on. Any ideas ?
 
I'd suspect a bad diode.

Make sure the wire connectors are tight, belt tightened. If the light still stays on, then stop by a shop who has one of the later(last twenty years or so)VAT(voltage amperage testers) that can test the charging system in the car. Almost all of the later units can test the diodes while the car is running, and most of them give you a printout for sending in with the failed alternator. If failed, I'd be asking for testing recompense and labor for r&r of a faulty alternator.
 
Roofman:

Is the ignition light on at idle speed and then
turn off at higher rpms? My light comes on at rpms
less than about 1000.

d
 
I simply hooked the unit up and when I went to start it the ignition light was on as I got in the car before even attempting to start it. Belt is tight, and battery charged, connection is tight for the wiring hookup.
What is a diod, and wouldn't that have been part of the rebuild?
 
Hello Roofman,

are you saying that the ignition light was on before you turned the ignition switch on?
A diode is an electronic one way valve. Typically there are six to rectify the alternating current (hence alternator) to D.C.. Yes they would be replaced in a rebuild.

Alec
 
Roofman-

I have no idea what is a diode. Probably something
inside the alternator.

My ignition light comes on as soon as I turn the key.
It does not go off until I get over 1,000 rpms.

My entire system is brand new and it has always been
this way. As soon as I top 1,000 rpms, the light goes off.
My fan belt is very tight and it makes no difference.

Does your light EVER go off? Or stays on all the time?

d
 
Well at least its working. However, the alternator should charge <Extinguish the light> at idle speed it is one of the principle advantages over the Generator. Perhaps you do not have the correct pulley on the alternator.--Fwiw---Keoke-??
 
roofman said:
I simply hooked the unit up and when I went to start it the ignition light was on as I got in the car before even attempting to start it. Belt is tight, and battery charged, connection is tight for the wiring hookup.
What is a diod, and wouldn't that have been part of the rebuild?
Click to expand...
Are you sure the connections to the alternator are correct ? I believe a 72 TR6 would have originally had the "5 pin" alternator, but your rebuilt is very likely a "3 pin". If the small brown/yellow wire somehow got shorted to the brown wire (right next to it in the later alternator connector), that would cause the light to stay on all the time when the key is off. Or of course if it's connected to the 'brown' terminal rather than the 'brown/yellow' terminal on the alternator.

Otherwise, you have a defective alternator and should return it. Happens distressingly often these days, apparently the new regulators (inside the alternator) are bad right out of the box. And most testers don't test the circuit for the warning lamp (since some alternators don't have it).
 
They rebuilt the alternator that was on the car so it is not the pully, as that was not changed.
This is what I have:
As soon as I plug in the harness to the alternator the ignition light goes on. When I start the car it goes off, and when I turn it off, the ignition light stays on unless I diconnect battery or the alternator harness.
When I start the car, the amp guage shows slight discharge with the needle in the "-" area about 1/8 inch or so to the right of bottom.
Battery is fully charged newer Optima gel battery, and belt is tight and good condition ( newer ).
My Alternator has 2 connectors, one has 3 large spades it connects to, and the other has 3 smaller spades that are in an "L" shaped connector. The connections appear to be good.
I called the guy who rebiult it today and he said to bring it over and he will retest on his "$20,000 test machine" .
 
Well, bring the alternator back and have him re-test it. On those Lucas alternators, it is possible to have one of the internal wires going to the wrong place and cause the symptoms you're having. As far as the $20,000 alternator tester, that's about what a fairly decent one costs. We've spent as much as $40,000 on alternator testers. Our shop has ten testers altogether, and, as information for TR3driver, everyone of them tests the light circuit. Virtually every car since the mid fifties has had a lamp circuit, and it is always part of the test procedure. Even the small jobber testers that we supply for the warehouses and large jobbers test the lamp circuit.

Now, having said that, it's quite possible to miss the fact that the lamp is on without the ignition switch on, as I haven't seen an alternator tester with an "ignition switch". The procedure is to hook up the battery cable and then plug in the the adaptor harness. The lamp circuit light will be on at this point. Start the test procedure. Motor turns off, lamp comes back on. Unhook the alternator and test the next one.

Normally, this is never a problem, but as I mentioned, there are some alternators because of there design, can be wired incorrectly inside...Lucas is one of them.
 
martx-5 said:
Our shop has ten testers altogether, and, as information for TR3driver, everyone of them tests the light circuit.
Click to expand...

My mistake then. My local FLAPS must have the only one in existence that doesn't pay attention to power being supplied into the lamp circuit. It doesn't even have a lamp, just a computer printout showing current and voltage.
 
If it were a diode, I think that it would be on all of the time. They are either good or bad.

I would take it back before you end up with a dead battery after driving it with the lights on one night.
 
I am taking it Monday, and will let you all know what goes on with the test.
 
TR3driver said:
martx-5 said:
Our shop has ten testers altogether, and, as information for TR3driver, everyone of them tests the light circuit.
Click to expand...

My mistake then. My local FLAPS must have the only one in existence that doesn't pay attention to power being supplied into the lamp circuit. It doesn't even have a lamp, just a computer printout showing current and voltage.
Click to expand...

Well, it's possible that the tester is actually checking the lamp circuit, but will only report if there is a problem. An actual lamp isn't neccessary. We only have one tester here where the operator has to actually look at the readings and info on the tester to determine if the unit is good or bad. The rest of them are programed as a "PASS" or "FAIL".
 
martx-5 said:
Well, it's possible that the tester is actually checking the lamp circuit, but will only report if there is a problem.
Click to expand...
Except that a friend of mine took back an alternator with this problem, and they said it was "fine". When he asked me to look at it, I found 12v on the lamp output. Of course, it's possible they just never put it on the machine and gave him the printout from another unit ...

This also isn't the first report I've heard of rebuilt alternators having this problem right out of the box, so at least someone/thing isn't testing for it.

Come to think of it, the battery machine at that same store also said my battery with the broken conductor "needed charged" even though it had just been charged ... I don't go to them for service work anymore.
 
Following up, this has turned into an ordeal. We have a local alternator shop and there is no doubt this guy knows what he is doing BUT....
Brought the alternator back to him and sure enough, a bad diode. He fixed that and, and rechecked the unit and tested for the ignition lite. I bring it home, put it in and same thing, ignition lite on, and amp guage shows slight discharge. Took it back again, says to change the jumper wire to a different spade on the alternator. So I did now have the previous problem plus the brake failure lite is now on. He seems honestly perplexed and has agreed to come over to my house and investigate further for me tonite or tommarrow nite after work. Maybe a happy ending soon. My question to the LBC braintrust is this: I have a 72 TR6 and the alternator is a Lucas 15 ACR. Was this the original model for my car?
 
Roofman,

I think the 15ACR was used until 1971, then they went to the 17ACR for a little more output. Some '72s used a Delco-Remy unit. There may be subtle differences in your harness for the alternator hook-up.

The 15ACR has two large blade connections and a separate plug with three small ones. If your car was made for a Delco-Remy unit it may not have the wires in the right place for a 15ACR. What kind of hookup do you have?

Jeff
1974 TR6 CF13816U
 
The plug in's I have are correct for the 15 ACR. There is one large black plastic plug in with a heavy brown / yellow wire that fits right into the opening on the alternator perfect. There is a 2nd grey "L" shaped connector that has 3 spades in it and it too fits perfectly. This is what was on the car when I got it and the wiring appears original.
When I plug them into the original 15Acr alternator I get the symptoms listed above. Had no problem before the rebuild with this wiring set up.
Anyone know what the 17acr hookups are like?
 
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