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I have a strange little problem with my '67 OTS. For a long time, I have driven the car without a functioning ignition light on the dash, as the light bulb was dead. A few days ago, I was doing some work under the dash, so I decided to finally replace it.
With the new bulb, the red light regularly turns on as soon as I turn the ignition key, but to my surprise, when I start the engine the light doesn't turn off, it just says solid red. Everything else seems to work fine, the battery charges normally, all other electric functions are OK. Any idea of what might be the cause?
I found the 6RA relay mentioned in the troubleshooting, but I can't locate the 3AW.
Other than the regulator, I don't see anything under the air heater box. What am I doing wrong?
Quick update: I think I just made a disturbing discovery. I reached with my hand behind the bracket the holds the regulator and I found 3 lose wires, protected with a plastic cap.
I strongly suspect that the 3AW relay in my car is not faulty, it's completely missing! I will order a new one and see what happen, but the challenge now is to correctly connect the three wires with the relay. One is ground and should be easy to find.
Anyone wants to take a guess on the remaining 2?
I have a strange little problem with my '67 OTS. For a long time, I have driven the car without a functioning ignition light on the dash, as the light bulb was dead. A few days ago, I was doing some work under the dash, so I decided to finally replace it.
With the new bulb, the red light regularly turns on as soon as I turn the ignition key, but to my surprise, when I start the engine the light doesn't turn off, it just says solid red. Everything else seems to work fine, the battery charges normally, all other electric functions are OK. Any idea of what might be the cause?
First tip: It's not really an ignition light. The light is intended to tell you that the key is in the on position, but the engine isn't running.
In 1967, it was probably still controlled by an oil pressure switch, which would be in one of the gallery ports on the right side of the block. But later cars had an electrically controlled light. In this case, the culprit would be a 3AW relay, which is a silver can just below the heater box. It would look like a turn signal flasher.
... it was probably still controlled by an oil pressure switch, which would be in one of the gallery ports on the right side of the block.
Can you please be more specific about location of this oil pressure switch? Turns out the the problem still persist also with the new 3AW, so I wonder if your theory is the correct one. I don't understand what you mean by "gallery ports" though. Any chance you could post a picture?
If your car is wired for a 3AW, it won't have a pressure switch. But something is strange here...If the three wires were completely disconnected, then the light wouldn't be lit, ever. So let's get some basic info:
1) Does your car have an original Lucas alternator?
2) If so, is there a wire connected to the AL terminal?
3) If the light comes on when the 3AW wires are disconnected, it means there's a short to ground somewhere.
This is the illustration of the OP switch from the parts manual. It would be on the right side of the block if you have it:
Thanks much for the additional info. I am quite sure that I don't have the oil pressure switch.
I have an original Lucas alternator and yes, one of the 3 loose wires is connected to it. As it stands, there is no 3AW connected to the car. Only the 3 loose wires, ending in the exact location where the 3AW should be. This makes me think that the 3AW was there and at some point and it was removed by the previous owner. The red light turns on when I turn the key, but it doesn't turn off as it should when I turn on the engine. The battery charges regularly and there are no electrical failures in the car.
With the ignition off, I used a multimeter tester to check the resistance between each of the 3 wires and the ground. As expected, the black wire reads near zero ohms. Then with the ignition on, I checked the voltage of the wires. Also in this case, as expected, the brown/black reads near 12V. and the other two both read zero V. This matches exactly with the testing instructions from Coolcat Corp. that RM9700 kindly shared above. I ordered a new 3AW from SNG Barrett and when I installed there were absolutely no changes to the scenario described above. I also have a modern solid state 3AW from Coolcat Corp. on its way and will try that as soon as it arrives, but I am not too confident that it will make any difference. This is driving me nuts!
I'll tell you now that the new 3AW won't fix the problem. The reason I say this is that with the 3-wire bundle disconnected, the system has no path to ground. The light shouldn't light at all. Somewhere, there's a short, and that needs to be fixed first.
I'll tell you now that the new 3AW won't fix the problem. The reason I say this is that with the 3-wire bundle disconnected, the system has no path to ground. The light shouldn't light at all. Somewhere, there's a short, and that needs to be fixed first.
I don't doubt what you are stating, in fact, I am sure you are correct.
Not easy to locate a short when everything is working correctly, though. Moreover, if there's a short, shouldn't I be blowing fuses all the time? All fuses are intact, so I don't have a clue of where to start here.
Your short is between the indicator light and the 3AW, on the ground side of the bulb. In fact, the first thing to check is the bulb socket itself, as it's possible that the ground wire is shorted to the case of the instrument. Another point: this circuit isn't fused.
I think you are onto something here. If you don't mind staying with me a little longer as I try a few things, I think I can solve this.
When you say "as it's possible that the ground wire is shorted to the case of the instrument", there is one important detail that makes me think you are on the right track: With no 3AW and the 3 loose wires, when I turn the key, the light turns on ONLY if I ground it manually with an extra wire, as if the bulb socket inserted in the instrument case was not grounded.
If your theory is right -- as I believe it is --I should see no continuity on the ground wire with the multimeter. Correct?
Ok, now I'm confused. In your original post, you said the light stays on when the engine is running. Now you say that the light is on only if you ground it. The bulb isn't supposed to ground at the socket, it only grounds through the 3AW. You can make the bulb light all the time by shorting the NB wire to ground. So exactly what is the symptom?
Your short is between the indicator light and the 3AW, on the ground side of the bulb. In fact, the first thing to check is the bulb socket itself, as it's possible that the ground wire is shorted to the case of the instrument. Another point: this circuit isn't fused.
Originally Posted by mxfrank
Ok, now I'm confused. In your original post, you said the light stays on when the engine is running. Now you say that the light is on only if you ground it. The bulb isn't supposed to ground at the socket, it only grounds through the 3AW. You can make the bulb light all the time by shorting the NB wire to ground. So exactly what is the symptom?
Fair. Let me try to clarify. 1. The light never worked on this car since I bought it. I thought the bulb was gone, so I checked and replaced. Even with the new bulb, the light was still not working. 2.I thought (perhaps mistakenly) that the socket was not correctly grounded when attached to the case. I have noticed that if I run an extra wire from the socket and ground it, the light turns on, however it continue to stay on even when the engine is running. 3. At this point I wrote my first post and through this thread, I learned about the existence of the 3AW relay. Subsequently, I discovered that my car has no 3AW at all, just the 3 loose wires. I though (probably mistakenly again) that I was dealing with 2 separate issues: needing a new 3AW while also had a bulb socket that did not ground correctly to the case. Then you and I started the conversation.
Fair. Let me try to clarify. 1. The light never worked on this car since I bought it. I thought the bulb was gone, so I checked and replaced. Even with the new bulb, the light was still not working. 2.I thought (perhaps mistakenly) that the socket was not correctly grounded when attached to the case. I have noticed that if I run an extra wire from the socket and ground it, the light turns on, however it continue to stay on even when the engine is running. 3. At this point I wrote my first post and through this thread, I learned about the existence of the 3AW relay. Subsequently, I discovered that my car has no 3AW at all, just the 3 loose wires. I though (probably mistakenly again) that I was dealing with 2 separate issues: needing a new 3AW while also had a bulb socket that did not ground correctly to the case. Then you and I started the conversation.
No, but I think your solution is now clear: reinstall the 3AW, and remove your ground wire.
It’s the very first thing that I tried. Did not work. The light doesn’t turn on at all.
no worries. I’ll keep trying and if I succeed I’ll post the solution, so it’s documented for others to use. Thanks much for all the support and suggestions.
Ignition Red Light
