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Ignition Warning Light stays on


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Having followed a thread on the 4a Forum re alternator options, I thought I would move my latest chapter to a more general area. I have a Lucas LR101 alternator fitted to a 4a with the thin belt conversion. New wiring loom with no Control Box. When engine first run last year, the ignition warning light extinguished when the engine started and the voltmeter indicated a charge when revs increased (also checked with multimeter). Then recently the ignition warning light stayed on; I did a number of checks (fan belt tight, no charge indicated when revs increased, connections checked for tightness). I replaced the alternator with same model, initially ran fine, light went out, all looked good. Started engine this morning to continue tuning set-up and warning light stayed on again! Any suggestions ? I find it hard to believe that 15 mins running would be enough to cook the diodes/voltage regulator on a new alternator (exhaust manifold heat shield fitted), but I can't think what else to blame

Many thanks

David

 

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Unfortunately not all the Lucas look-alikes are built to the same standard David.  Of course It may not be heat causing the problem -  it could be vibration breaking a connection internally. 

If it is new the seller should replace it of course but if not It would be worth opening it up if you can, and taking a look at the connections and the slip-ring brushes.  Replacement parts are cheaper than a whole new alternator. 

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If the ignition warning light holder insulation has failed it will stay on and also cut off the alternator. Try pulling the holder out of the speedo housing and see if the light (now yellow bulb) stays on or acts as it should. This may not be your problem but well worth trying. Brings back painful memories!! If you replace the ammenter with a voltmeter it is easier to see what's happening.

Best of luck.

Peter

 

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Hi David,

did you change to a LED bulb for the warning light?

I’ve been told with this the current is too low to start the alternator charging.

Ciao, Marco 

Edited by Z320
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48 minutes ago, petertrs said:

If the ignition warning light holder insulation has failed it will stay on and also cut off the alternator. Try pulling the holder out of the speedo housing and see if the light (now yellow bulb) stays on or acts as it should. This may not be your problem but well worth trying. Brings back painful memories!! If you replace the ammenter with a voltmeter it is easier to see what's happening.

Best of luck.

Peter

 

Thanks Peter, the ignition warning light is in a separate holder on the 4a and yes I tried that, no change. I have a voltmeter fitted vice the ammeter, but thank for your thoughts

David

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37 minutes ago, Z320 said:

Hi David,

did you change to a LED bulb for the warning light?

I’ve been told with this the current is too low to start the alternator charging.

Ciao, Marco 

Hi Marco, the warning light has remained as an incandescent lamp as advised by Duncan Rickards at Classic Car LEDs, but thank you

David

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3 hours ago, RobH said:

Unfortunately not all the Lucas look-alikes are built to the same standard David.  Of course It may not be heat causing the problem -  it could be vibration breaking a connection internally. 

If it is new the seller should replace it of course but if not It would be worth opening it up if you can, and taking a look at the connections and the slip-ring brushes.  Replacement parts are cheaper than a whole new alternator. 

Thanks Rob, I am going back to H Bowers to see if I can get this unit replaced

David

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Hi 

As already mentioned above some "new" alternators on the market are not very good quality you can if you use Euro car parts drop down car finder menu get a exchange alternator for a ford cortina/escort that will fit (there list just goes back far enough)  

Chris

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so the alternator has been bench tested by H Bowers and found to be all ok. My ignition warning light remains on however the voltmeter is showing a charge, so I'm a bit stumped as to what to try next. Warning light remains on when holder pulled out of the dash rear

David

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^ +1  

When I rewired my 3A by using a 4 way block and installing two fuse boxes I could not see where the cable feeding the ignition warning light connected to the alternator and had to do t by feel. I pushed the insulated Lucas clip under the prong so no connection and warning light on all the time.

An alternative might be that you have a partial break in the cable(s) from the alternator to the warning light which physically breaks completely with the vibration of driving. 

One for the experts - would a short in the cable from alternator to lamp cause the lamp to stay on?

Can you run a temporary cable from the alternator to the warning light to test the theory?

Miles

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30 minutes ago, Lebro said:

Maybe your warning lamp is not wired into the right place ?

Bob

Thanks Bob, thing is it was working previously and I haven't changed anything in the interim other than pulling alternators for replacement

Rgds

David

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9 minutes ago, MilesA said:

^ +1  

When I rewired my 3A by using a 4 way block and installing two fuse boxes I could not see where the cable feeding the ignition warning light connected to the alternator and had to do t by feel. I pushed the insulated Lucas clip under the prong so no connection and warning light on all the time.

An alternative might be that you have a partial break in the cable(s) from the alternator to the warning light which physically breaks completely with the vibration of driving. 

One for the experts - would a short in the cable from alternator to lamp cause the lamp to stay on?

Can you run a temporary cable from the alternator to the warning light to test the theory?

Miles

That's a good thought Miles, I'll try that. I'm wondering whether the cable to the warning lamp has been touching the exhaust downpipe at some point and damaged the cable

Rgds

David

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If the alternator has checked out OK, the only way the lamp will stay on is if the brown/yellow wire to the alternator has somehow become earthed instead of making to the connector.   If the wire is open circuit the lamp cannot light.  

If the wire is properly connected but has also become earthed,  that will damage the alternator because the diode 'triple', which feeds the alternator regulator and the ignition lamp, would be shorted and burn out. Since the alt is working I doubt that has happened. 

The only other thing that may have happened is that the feed end of the lamp from the ignition switch has become earthed. In that case the lamp would be off until the engine was running. If it comes on as normal, as soon as the ignition is switched on, it cannot be this. 

 

ignlampcct.jpg.a2687741f9ad8848e76296468d3261ef.jpg

 

Edited by RobH
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The lamp gets power from the ignition side of the wiring, and earth's through the alternator. So you switch on ignition, bulb ignites, you start the car and the alternator now pushes 12v back up the cable that was providing the earth thereby extinguishing the light. 

So if it stays on when engine is running it must be going to earth somewhere, either the alternator isn't supplying its 12v or that same wire is going to earth through a damaged wire. 

Gareth

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13 minutes ago, Mk2 Chopper said:

The lamp gets power from the ignition side of the wiring, and earth's through the alternator. So you switch on ignition, bulb ignites, you start the car and the alternator now pushes 12v back up the cable that was providing the earth thereby extinguishing the light. 

So if it stays on when engine is running it must be going to earth somewhere, either the alternator isn't supplying its 12v or that same wire is going to earth through a damaged wire. 

Gareth

I would also suggest an earth fault as Gareth has already. 

Keith

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  • 2 weeks later...
On 6/30/2022 at 12:34 AM, trchris said:

Hi 

As already mentioned above some "new" alternators on the market are not very good quality you can if you use Euro car parts drop down car finder menu get a exchange alternator for a ford cortina/escort that will fit (there list just goes back far enough)  

Chris

We may need to replace the alternator on my friend's new TR4A project. The owner mentioned the alternator was replaced late last year and it has been acting weird last couple of weeks. We'll take a closer look this weekend after we finished installing the suspension and mud tires on the Wrangler. I'll tip him about getting a ford alternator.

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4 hours ago, CarreyRT said:

if you use Euro car parts drop down car finder menu get a exchange alternator for a ford cortina/escort that will fit

A after-market alternator for a Ford isn't going to be any different- there's nothing special about them, they probably all come from the same far-east factories.  Just buy a decent one from a reputable supplier - not an e-bay cheapie. 

 

 

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Ok so having got the car running and been for a 10 mile drive, everything seems ok...but the ignition warning light stays on. I've tried the suggestion of running a separate temporary wire direct from the back of the alternator (brown/yellow connector) to the warning light - no difference, stays on when engine running. I also hooked up a volt tester to the battery  +ve and -ve whilst the engine was running, when I blip the throttle the voltage stayed steady at 12.4V so I don't think that's charging...so back to the suspect alternator (I can't explain why the one I sent back to H Bowers tested ok on their testing rig...)

Any bright ideas?

David

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Definitely not charging David, as you say.  How are you keeping the battery charged?  Do you use a battery conditioner?  

(I'm wondering if there is anything that is connected that could be killing the alternators........)

That wouldn't explain why it tested OK at Bowers though.  Some alternators might not start-up if the lamp current is too small,( hence the question above about LED bulbs). It might just possibly be something like that if the Bowers tester uses a beefier bulb than yours but it's very unlikely. 

There's no way a bad connection can be doing this.  There must be an earth because the lamp is on. The lamp connection must be good because ditto.   A bad output connection won't affect the ignition lamp and the alternator will generate regardless. 

It's a mystery. 

 

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Thanks Rob, that's kinda where I'm at. I'm going to order a remanufactured original Lucas unit from Powerlite, I got a starter motor from them and very happy with that and I've chatted to them at a couple of shows, they seem fairly decent guys. Any better suggestions?

I might in due course change it out for a ND unit, but not fully convinced yet and I want to get this sorted asap

Regards

David

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8 minutes ago, RobH said:

Definitely not charging David, as you say.  How are you keeping the battery charged?  Do you use a battery conditioner?  

(I'm wondering if there is anything that is connected that could be killing the alternators........)

That wouldn't explain why it tested OK at Bowers though.  Some alternators might not start-up if the lamp current is too small,( hence the question above about LED bulbs). It might just possibly be something like that if the Bowers tester uses a beefier bulb than yours but it's very unlikely. 

There's no way a bad connection can be doing this.  There must be an earth because the lamp is on. The lamp connection must be good because ditto.   A bad output connection won't affect the ignition lamp and the alternator will generate regardless. 

It's a mystery. 

 

and yes I use a conditioning charger on the battery, CTECK 3600

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+1 for your experience with Powerlite, in my case a damaged starter motor (my fault not theirs). 
It was maintained to me that everything is built in-house at Brierley Hill. Or was that assembly only!

james

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          I had the same problem as David, the ignition light would not got out but a good charge was showing on the ammeter so I disconnected the ignition light and everything continued to work as normal. Inspired by this thread and the wiring diagrams shown I have had another go a the problem first using a remote light and this worked so I wired in the ignition light and that now works, its a mystery. Thanks for the inspiration and advice.

          Cheers

          Richard

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