4 replies to this topic

[80sMiniCity]

Hi All,

 

I upgraded my stock Lucas A115 to an A127 after the original stopped working.  Since I never had an A127 before, I’m not sure if it’s working correctly or there might be a problem. I just assumed it was a direct replacement.

 

The A127 will not charge if the IND (warning light) terminal is connected.  The warning light on the spedo will light and stay on and no charge.  the only way I can get it to charge is to connect 12 volts to the IND terminal without the light.  It doesn’t need a constant 12 volts, just when it starts.  If there’s a load on the wire, like the warning light, it won’t charge. If I connect the warning light wire after it starts charging, the warning light on the spedo stays on even when the alternator is charging.

 

Could it be a bad regulator or is this normal for this alternator?

 

Thanks...

[MikeRotherham]

I was told that you needed the warning light to be present to start the alternator charging otherwise it wouldn't.

 

The warning light hasn't been swapped for an LED has it?

[80sMiniCity]

Let me try and explain the problem again. I think my original post is confusing.

 

Alternator in the car…

• Turn the ignition on…the original Incandescent bulb lights up, no LED lights used.
• Start the car and the light stays on.  No voltage coming out of the Alternator. Looks like a DOA replacement alternator.

Alternator on the bench…I read the on a higher AMP replacement alternator you need to put a 10 ohm resister in series with the bulb to trigger the regular.

• I added a 10 ohm resister, in series to the wire with an 5 watt bulb to the IND terminal.
• B+ terminal back to the positive 12v car battery, negative battery terminal to the alternator metal housing
• The multimeter shows 12.6 volts at the battery
• The bulb is on
• I turned the pulley nut with my trusty drill and the same as in the car, voltage at the battery stayed at 12.6 volts and the alt light stayed on.

I tried connecting a wire from the battery directly to the alternator IND terminal, no light or resistor.

• Turned the pulley nut again and 14 volts at the battery.
• I disconnected the IND wire while the alternator was spinning and the voltage stayed at 14 volts.
• I reconnected the light to the IND terminal while the alternator was spinning; the light was on and 14 volts at the battery.

Conclusion…(is this normal?)

1. The A127 need to see 12 volts on the IND terminal, with no load, when the alternator stars to turn.
2. The 12 volts at the IND terminal is not required once the alternator is running.

 

Note: The terminal on top of the B+ post is used for the noise suppression capacitor, not in the image.

 

 A127_b.jpg   27.45K   1 downloads  A127_b.jpg   29.88K   1 downloads

[MikeRotherham]

I used to have a TR7 on which the alternator, which had been replaced by a previous owner, would only kick in and the warning light go off when the engine was revved much much higher than the idle speed.

 

Is it something like that?

 

Re reading your original post my symptoms above only match the first bit of your explanation.

 

I think i would check, with a decent auto electrical shop ( and good luck with that one) to see if the replacement is a direct swap for the alternator that failed.

Edited by MikeRotherham, 01 May 2019 - 07:23 AM.

[nicklouse]

Sounds like an issue with the bulb or the wiring. As the bulb is on it should be giving 12v to the alternator. Is it?