No ignition light today - yesterday yes. Go figure

The ign light had been working fine all the while, but today, not.
With the key in the on position without engine running, no light.
The bulb is good, I have 12 + a bit vdc at the bulb socket, all connections are good, clean and tight.
I ran a jumper and grounded the socket base thinking the socket may not be seeing ground. N/G
With the engine running, the charge rate is ~13.5 vdc. Same as when the ign light was working.
May I ask what my next step would be?
Thank you
Carlo

Check the 3AW relay.

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Like Marco sez…

Most likely the 3AW relay, left side under the bonnet right of the battery on the firewall.

SNG has them:

3AW solid state upgrade relay

To test the existing, disconnect the relay from the car. there should be a resistance between the AL lead and the E lead, between 16 and 20 ohms. If no conductivity between AL and E, the relay is defective.
measure the resistance between WL and E. should be close to zero.

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The 3AW failed on my S2. I replaced it with the electronic version Mike sells:

https://www.coolcatcorp.com/Merchant5/merchant.mvc?Screen=PROD&Store_Code=CEC&Product_Code=SS3AW&Category_Code=EL

To make it a bit stealthy I opened up the old unit, removed the innards & wired the electronic thingy to piggyback on it:

You’d have to be fairly nosy to see the little black box:

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I had same problem. I opened up the relay and very lightly filed the contact that it makes when there is no voltage. Problem solved.

Dennis 69 OTS

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Dana, thanks I’ll test it in the morning.

Thanks for the coolcat suggestion and idea, Geo

Dennis
But I do have voltage at the bulb socket! Is that the location you mean?

IIRC the switch opens the ground circuit

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Voltage goes from Battery, to the warning bulb, then to the warning relay. So you will see voltage as you do.

The warning relay, with engine off, has a contact that is closed and thus connects this voltage from the bulb to ground. This completes the circuit and the bulb glows

When the alternator generates enough voltage, the contact inside the warning relay is pulled open and the circuit is broken (no more path to ground) so the light goes off.

So your problem may be that the contact in the warning relay has some oxidation on it and is not completing the circuit to ground when the engine is off.

The place to start is to check all the connections etc. Someone posted a checking procedure some time back.

If that reveals nothing, you may decide to open up the relay. If you do so, I can show you the contact part that can be cleaned with a very small file!

Dennis 69 OTS

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Mine failed because the bimetallic had lost tension after 50 years, a little adjustment and it worked fine.

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All good info. I’ll check things today and post the results.
Thank you, gentlemen.
Carlo

Here’s a local thread on the 3AW that covers it pretty well, from angles you aren’t even worried about…

Everything 3AW that matters

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I testing the relay and it’s a dead thing. I opened it up, and found little pieces of tiny wire that were at one time connected to something else inside. No wonder this wasn’t working. Before this I jumped the wire leading to the bulb and the bulb lit.

I’m going the coolcat route for Mike’s ss relay

Thank you
Carlo

Mine failed when the nichrome wire broke - sounds like yours may have gone that way too.

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Not obvious in the pic, but seems to be the same here

Carlo it can be two things. If you have a diode failure in your alternator it will not complete the circuit to the warning light. It could also be the 3aw warning light module has failed. With the engine running check the voltage at the ALT terminal. If it is greater than 7.5volts you have a diode failed which will normally burn out the 3aw as well. An easy check is to remove the NB (Brown/black) wire from the 3aw and ground the wire to the chassis (somewhere). With the ignition on the light should illuminate. If not you need to check the fuse in the number # fuse block. If it is ok you have a bad bulb. I developed a change of the alternator to a GM AC Delco which is very easy and inexpensive to perform. A complete new installation will be less then $75.00
and literally trouble free. Send me a email and I will send you the instructions. dickathometwo@yahoo.com

Yes, Dick- exactly what I did, and the light illuminated. Then I opened the relay and found a broken connection and bits of wire in the relay.

I’m going to run a voltage check on the alternator as you suggest to make sure my new relay isn’t in jeopardy.

Thank you
Carlo

P.S. Email on the way

Normally that is caused by a diode failure. Like I said, if you have more than 7.5 volts at the ALT terminal on the alternator you will fry a new 3aw which sounds like what has happened. The alternator I call for is without air conditioning. If you have air you will have to use a similar alternator but with two mounting ears, still at least 63 amp.

Dick

CarloM
Carlo 1970 E 2+2

    November 29

TrickyDicky:
An easy check is to remove the NB (Brown/black) wire from the 3aw and ground the wire to the chassis (somewhere).

Yes, Dick- exactly what I did, and the light illuminated. Then I opened the relay and found a broken connection and bits of wire in the relay.

I’m going to run a voltage check on the alternator as you suggest to make sure my new relay isn’t in jeopardy.

Thank you
Carlo

P.S. Email on the way

Question, When I replaced my original 11AC alternator with a new Lucas clone with built in regulator the red ignition light stopped working. Did I fry the 3AW somehow? Do I even need the 3AW? If I replace with a new 3AW any precautions on hook up?
I do not recall if the red light stopped working after my original 11 AC failed (one wire shorted to case)
FWIW my original 60 amp alternator often ran in discharge where my new 55 amp alternator never gets anywhere near discharge. This is a A/C car.
Glenn

Glenn, with the engine running at 1200-1500 RPM check to see what the voltage reading is at the ALT Terminal on the alternator. If it is above 7.5 Volts you have fried the 3aw. On the other hand, may I suggest a small test. Disconnect the brown/black wire from the 3aw. Turn on your ignition switch to the run position and ground the wire removed from the 3aw. The ignition light should be illuminated. If not, you have a bulb burned out or the fuse at #6 fuse block is blown. I don’t know how your new alternator is internally wired but since it is internally regulated I need you to verify the brown/yellow wire on the 3aw goes to the ALT/#1 terminal on the alternator. If it does and you verified the ign. light illuminated when you grounded the Brown/black wire, then by connecting the two wires NY and NB together (at the 3aw) the ign. light should go out when the engine is running above 1200 RPM. The 3aw was just to show you the alternator was on line and functioning properly. Primarily all three diodes working (converting AC to DC at approx. 14.1-14.3 volts which you read on the battery posts when engine is above 1200 RPM.

Please let me know what you come up with after you do the above test.

Dick

Is looking for < 7.5 volts ( AC or DC ? )performed with key on and engine off? And how much below 7.5 are we looking for?