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Discussion Starter · #1 ·
Several questions. I replaced my seat belt warning light relay with a NOS replacement tonight. (as usual, that was problematic itself. Assy manual says that it should be assembled with the screw tab UP, this was put in with the tab FOREWARD. But I digress.) Seat belt light bulb is known to be good.

It's too late to start the car without waking up the boy, but I did put the car into Acc. Nothing on the light.

1) Does the car need to be started to activate the relay/light?

If the answer to 1) is no, the wiring could be bad, or both relays could be burned out. Or, I suppose, both may be good if it's the wiring.

2) Can I test the relay for operation out of the car?

3) If either are burned, can someone give me instructions on how to repair it? I'm pretty handy with a soldering gun. It'd be nice to have a repaired backup.

As always, thanks for your knowledge,

Steve
 

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Steve do you have a wiring diagram for this? I just bought a seat belt light and am curious how it hooks up now.
 

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Discussion Starter · #3 ·
There's one in the Electrical Assembly Manual, and in the wiring diagram "book". It basically runs off the same fuse as the radio, running through a relay.

If you only bought the light, you'll need to locate a relay as well. It's a non-repro'd part.

Steve
 

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The answer to number one is no, the car does not need to be running. However once you turn the ignition on, and trip the light, you have to turn the ignition off and wait a few minutes before you can trip it again. Sorry, I don't have the answers to the other questions.
 

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Discussion Starter · #5 ·
Whiz (or any other electrical guru),

- I would think I could apply some small voltage to the contacts to cause the relay to close, yes? That would allow me to test the relay outside of the car. So this is the same as asking:

- What SHOULD the voltage through the relay contacts be?

My wiring is so messed up. (Or at least out of spec). There's this strange red wire wrapped around the bottom of the steering column. I finally traced it through, and a PO spliced the seat belt warning light wire and connected the A/C to it. My wiring diagrams say that this should be a wire running off the back of the ignition switch. I have to wonder what else is f*cked up in there. It's almost enough to make me buy a whole new harness and rewire everything from scratch.

Blech.

Steve
 

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Here's how I think it works (couldn't find it on schematic I have). The relay is a thermal, normally closed time delay relay. After turning on the ignition switch, power is applied to the accessory circuits including the seat belt warning relay. Power passes through the normally closed contacts of the relay and illuminates the warning light. At the same time power is applied to the relay, a thermal bimetallic element is heated inside the relay. After a predetermined time period, the heater causes the bimetallic to bend and open the contacts in the relay that feed power to the warning light.

Hence power should be on all the relay contacts the minute you turn on the key. Power should disappear on the contact feeding the warning light after the predetermined time period. Use a 12 volt test light or multimeter to test what's going on at the relay contacts. The relay case itself may have to be grounded for it to work.
 

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Discussion Starter · #7 ·
So, on a cold, working relay, I should see continuity between the contacts, yes? And in any case, shorting the "L" shaped connector from the lightbulb should cause it to be constantly on, right?

Steve
 
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I just replaced the carpet in our 66 Mustang. I did not see any wire connections to either side of the seatbelts. I do see the seatbelt warning light under the dash but I have never seen it on.
When should this light come on?

We just bought this car and I am not sure as how it should operate.
 

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Discussion Starter · #9 ·
The seat belt warning light is not connected in any way to the actual seat belts. It's more of a reminder light. It's simply connected via a relay, which should make the light illuminate for about seven seconds when power is first applied.

It is very common for the relays to be burned out, however.

Steve
 

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I was reading a post regarding the seat belt reminder light bulb 1895 could heat up and cause melting of the red lens. It showed an equivalent bulb that had about 1/2 the wattage. I cant find that post. Could someone give me an equivalent bulb number to use in that socket. I just replaced the relay with a NOS relay I bought on Ebay and its now working fine.
 

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The lens melts when the OEM relay dies, closed (on) and the warning runs forever instead of a few seconds seconds. In normal operation, the lens would last indefinitely.

If you only bought the light, you'll need to locate a relay as well. It's a non-repro'd part.
There is a replacement, though.

Warning Lamp Relay, replacement type

You can also get a replica of the whole setup-


The repro uses an LED, so even if were on full-time, it wouldn't melt the lens.
 

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This is a 12 year old post and the OP has been banned.
 

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Thanks for the info 22GT. I purchased a NOS relay off EBay and it it working fine and turning off after about 30 seconds, but I was concerned about the bulb melting the plastic lens. I guess since its is functioning as it should, the bulb shouldnt melt the lens. But I will continue to search again for the post that I saw here regarding a lower wattage bulb that would work in the socket. Again, thanks.
 

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Thanks for the info 22GT. I purchased a NOS relay off EBay and it it working fine and turning off after about 30 seconds, but I was concerned about the bulb melting the plastic lens. I guess since its is functioning as it should, the bulb shouldnt melt the lens. But I will continue to search again for the post that I saw here regarding a lower wattage bulb that would work in the socket. Again, thanks.
Just use an LED bulb. Virtually no heat at all.

Amazon.com: LED-T10-BA9S-R-1LED-10MM-WH, T10 Adapter 1895 BA9S BA9 T4W 10mm LED 12V Bright White Led Light for Interior Dome Lamp Trunk Door Panel Center Map Console Bulb: Automotive
 

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Hi, I purchased an NOS relay as well. I haven't been able to figure out how to access it to change it since it seems like its buried pretty good under the dash. Any hints on how you were able to access and change the relay?
 

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I was reading a post regarding the seat belt reminder light bulb 1895 could heat up and cause melting of the red lens. It showed an equivalent bulb that had about 1/2 the wattage. I cant find that post. Could someone give me an equivalent bulb number to use in that socket. I just replaced the relay with a NOS relay I bought on Ebay and its now working fine.
 

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Its been a few years since you installed the relay. Looks like it is tough to get to. My car is a 66 and I bought a 65a7-10B926-2 Relay assembly. I wonder if this is the right part number.
 

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Since the Seat Belt Warning Light was only available as part of the Deluxe Seat Belt Factory Option, and not as an Accessory, no separate set of Instruction Sheets were available for it.
However, as noted previously, its installation is shown in the Electrical Assembly Manual. I have attached a copy of the appropriate page, as well as two pages from the 1966 Mustang Accessories" Section of the 1966 Ford Wiring Diagram Manual.

The Relay itself is Ford Service Part Number C6AZ-10B924-A. It is usually ink stamped with the Identification Number of C6AB-10B924-A or -C. It is Tung-Sol Relay # 673.

Over the years, I have successfully repaired several of these. As was mentioned earlier, this Relay has a set of bi-metallic strips that are normally closed (touching each other). As power is applied (ignition switch turned on or to start), the heat from the electricity expands the two strips at different rates, resulting in the strips separating from each other, thus opening (turning off the power) the connection. Just like ignition points, or the points found in the self-winding electric clocks, over time, the points can become burned and rough, or become corroded from sitting for some time (even with new ones that have sat on a shelf for years). All you need to do is to carefully bend up the tabs on the underside of the Relay that hold the fiber "board" in the housing, remove it and then sand the set of points with an ignition file, cardboard nail file, or doubled over piece of 180 or so sandpaper, and smooth the points so they contact each other correctly. As with the clocks, I have found this to be the usual problem, and the "fix" I described usually corrects it. If it doesn't, then be prepared to spend about $75 to get a new Relay, assuming you can find one. Even the new one still may need cleaning.

Hope this helps.

Bob
Seat Belt Warning Light EAM E6-8575-1.jpg
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