Testing Settings of a Bulb Failure Module
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Testing Settings of a Bulb Failure Module
Hi All,
I wondered if those with a good appreciation of electrics could give me a bit of advice.
As part of my project to work out how to fit LED bulbs whilst keeping as much of the bulb failure systems intact as possible, I've been playing around with the tail light bulb failure modules.
Basically these modules seem to use a bimetallic strip which heats up and deflects when the tail light circuit is activated. With sufficient current draw, deflection is achieved and it turns off the bulb failure light.
The module uses 3 wires. It seems to take a voltage input on one wire, passes that through via an output wire to the bulb. And uses a third wire as the voltage output to the bulb failure light. This wire (White and Slate, shows 12+v when the light switch is activated and the bulb failure light illuminated as it enters test mode (which actually just means the bimetallic strip is heating up) As the strip deflects and makes contact, the voltage drops out on that wire (or seems to register about .15v by my measurement) and the warning light extinguishes.
My approach to allow LED bulbs to function has been to adjust the bi-metallic strip so that it needs less current draw to sufficiently deflect and still turn out the warning light. That's been a bit of a trial and error routine. But I seem to have achieved it.
Ideally, what I want to do is measure how much current it needed originally and then work out how much I've changed it by to allow the LEDs to work. I can then publish a more definitive process than "turn it about an 1/8 of a turn". And actually quote a resistance (?) figure so that owners can adjust the module accurately.
So, what and I how should I be measuring?
Can / Should I measure the resistance between of the circuit from the input voltage terminal to the bulb failure output terminal (the W/S) wire as originally setup? And then compare that to the resistance that seems to exist when I've adjusted the module to get the LEDs working? Or is that not possible / valid?
I hope that all makes sense!
Grateful for any feedback.
Tks
Paul
I wondered if those with a good appreciation of electrics could give me a bit of advice.
As part of my project to work out how to fit LED bulbs whilst keeping as much of the bulb failure systems intact as possible, I've been playing around with the tail light bulb failure modules.
Basically these modules seem to use a bimetallic strip which heats up and deflects when the tail light circuit is activated. With sufficient current draw, deflection is achieved and it turns off the bulb failure light.
The module uses 3 wires. It seems to take a voltage input on one wire, passes that through via an output wire to the bulb. And uses a third wire as the voltage output to the bulb failure light. This wire (White and Slate, shows 12+v when the light switch is activated and the bulb failure light illuminated as it enters test mode (which actually just means the bimetallic strip is heating up) As the strip deflects and makes contact, the voltage drops out on that wire (or seems to register about .15v by my measurement) and the warning light extinguishes.
My approach to allow LED bulbs to function has been to adjust the bi-metallic strip so that it needs less current draw to sufficiently deflect and still turn out the warning light. That's been a bit of a trial and error routine. But I seem to have achieved it.
Ideally, what I want to do is measure how much current it needed originally and then work out how much I've changed it by to allow the LEDs to work. I can then publish a more definitive process than "turn it about an 1/8 of a turn". And actually quote a resistance (?) figure so that owners can adjust the module accurately.
So, what and I how should I be measuring?
Can / Should I measure the resistance between of the circuit from the input voltage terminal to the bulb failure output terminal (the W/S) wire as originally setup? And then compare that to the resistance that seems to exist when I've adjusted the module to get the LEDs working? Or is that not possible / valid?
I hope that all makes sense!
Grateful for any feedback.
Tks
Paul
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