Ignition light stays on and slowly pulses

Engine has been difficult to start and running unevenly. I found a broken spark plug lead connector (the end that pushes in to the distributor cap) that made for a bad/loose connection. As a precaution I have fitted new leads to all the plugs. I also fitted new spark plugs, a new distributor cap, and a new 3 ohm Flame Thrower coil. The car now starts first time and seems to run just fine (though I have not driven it yet). But now the ignition light stays on (and steadily pulses) when running the engine above idle speed. It went out just fine before I made these changes. I have not touched the timing. Battery is fully charged. Any idea why any of the things I’ve listed here may have caused the warning light to stay on?

S1, S2, S3, or Chevelle?

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E-Type S2 1970

Your problem is corrosion causing resistance in one or more electrical contacts.

I suggest you (with engine off) go to the voltage regulator and pull off the connector and put it on a few times. If you have electrical contact spray, use it also
Then go to the alternator field relay and pull off and push back on each connector a few times. Should there be connectors that do not have a lot of physical resistance to pulling them off, give them a little crimp with needle nose pliers to tight them up.
The alternator relay has a connector that goes to ground. Do check it also and make sure the actual ground connection is good

69 OTS

Thanks Dennis I’ll give that a try.

I had the same problem.
I did the fix and 9 months later it came back.
I then took off each female connector and crimped each a bit with needle nose pliers.
It has lasted 2 years.
The connector to the voltage regulator has three female connectors in it. They can be released by pressing a metal tag for each through a little hole in the connector. If you can’t see how to do it, private message me.
One of the relay connectors goes to ground. you may want to trace and find the ground and clean it up.


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Hopefully, the above magic works for you. If not, probable causes:

1 Blown 3AW
2) Bad alternator diode
3) Bad voltage regulator
4) Bad brushes
5) Carboned or burned alternator relay contacts

Thank you.

Actually, I should have given you some trouble shooting tips:

  1. With the car running, what voltage do you measure across the battery terminals? It should be at least 13.5. If it’s 12-12.5, it’s because the alternator isn’t charging. VR problem, alternator relay, brushes or the alternator itself.
  2. If the alternator is charging, the problem is in the 3AW circuit. Measure the voltage between the AL lead and ground (with the car running), using the AC scale of your DVM. it should be 7-9VAC. If not, the AL wire is disconnected somewhere. If the voltage is there, remove the 3AW and check for continuity between the AL and earth terminals. If it’s open circuit, the 3AW is bad.

Thanks, I’ll check the voltage. I guess my ‘puzzle’ is that the ignition light was fine before I put in the new plugs/leads/dist cap/coil. Is there anything about making these changes that could cause the light to stay on, or is it just a coincidence.

Most likely a coincidence.

But it would make sense to check the connections at the alternator, in case you accidentally disconnected something.

I bookmarked the following thread a while ago.
(I was particularly surprised by the possible problem caused by AGM batteries.)

Anyway, it provides a lot of details for the suggestions posted above.

I hope it helps!

- Tom -

For what it is worth, the solution to my on again, off again, ignition light was a new voltage regulator.

Looks relevant. Thanks.

I’ll try that if cleaning and checking connections doesn’t work.

Well that did the trick. Cleaned the voltage regulator connections and bingo! Ignition waring light behaving normally. Thanks for the tip.

Great to hear