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Aother question tonight

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JPSmit

JPSmit

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I have a lighting issue.

Again, having the Bentley 1500 book open to page 330 is helpful.

When I connect the battery, light #50, the ignition warning light goes on. When I start the car it goes out.

According the the owners Manual - same Bentley book - page 6 I think. this light exists to both remind me that the key is in the ignition and tell me that the engine is not charging. Thus, it should light up at low idle and go off when I accelerate AND it should tell me to turn off the key when the engine is not running.

The obvious solution is to take out the bulb - problem solved. The only problem is that I want it to be right. Any ideas? I tried getting continuity from the alternator but couldn't - I presume because of resistance from the bulb.

any thoughts?

thanks all
 
I am confused. Is the light on when the key is not in the ignition switch?
 
don't pull the bulb... My understanding is that the bulb is in series with the charging circuit. No bulb, no charge.

Mine flickers all the time. I just live with it.
 
The "ignition" light will go out if the generator or alternator is doing anything useful at all. Even if the battery is discharging heavily, as long as the generator is working, it'll go out. Maybe, under heavy electrical load and very slow idling, you might see it start to light up, but don't expect it to go on just because the car is idling.

Yes, don't remove the bulb. Some alternators need it to leak power the field coils before the generator output ramps up. Really shouldn't be necessary, but sometimes it is.

Beyond that--I'm not directly familiar with the operation of the later midgets, but usually the light will go on as soon as you turn on the ignition switch, and go off when the switch is off or the engine is running. I've never seen a car where it goes on just because the key is in the ignition, with the ignition off, but it certainly could be done.
 
Morris said:
I am confused. Is the light on when the key is not in the ignition switch?
Click to expand...

yes - and that is the problem - if the battery is conected, the light is on key in or key out
 
You could still be getting some current leak from that brake warning light circuit or possibly the buzzer circuit. Also, it could be a bad ignition switch.

If you take out the bulb, your alternator will not charge.
 
texas_bugeye said:
regulator cut in problem ?
Click to expand...

not sure what that is?
 
A 1500 doesn't have an external voltage regulator; it's inside the alternator. It sounds like a short to me: the light thinks the ignition is on when it isn't. From what I understand (correct me if I'm wrong, somebody!) the ignition light on a 1500 acts like a push-me-pull-you, electrically. The light gets juice from the battery and grounds to the alternator, when the ignition is on, and turns the light on. When the alternator's running, it sends power back up the ground to the light. The voltages cancel and the light goes out. If your battery's bad, the push from the alternator is greater, and the light goes on. If the alternator's bad, the push from the battery is greater, and the light goes on. The alternator needs the light in the circuit to read the voltage from the battery. No light, no juice, no charge.
 
sounds like I need to pull the alternator since that seems the most logical
 
Yeah, no cut-out relay in a 1500. Duh!

The light is turned completely off through the normal channels when the ignition is off, so it seems that, if everything is wired correctly, the only way it could get powered is from some unintended path through the regulator. So, my best guess is that (1) something is miswired (most likely) or (2) something wrong with the regulator. This would not necessarily prevent alternator output, but it would probably show up as system voltage that wanders all over the place. You can check this with a voltmeter, but be sure to use a moving-coil (analog) voltmeter, not a digital one, since the digital one can be upset by electrical noise in the system.
 
am I correct that with the motor running I should be able to measure the alternator voltage output across the battery terminals?
 
Yep. When you rev the engine it should go up to about 14.5 volts. If it spikes way higher the internal regulator's bad; if it doesn't change at all it's either the alternator or something in the charging circuit.
 
Thanks - I think it is the later
 
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