aftermarket temp guage changes temp when lights or ac is on?
05-02-07, 01:41 AM
#1
I "lost" my emissions....
Thread Starter
aftermarket temp guage changes temp when lights or ac is on?
ok my temp guage must be wired wrong.
i have it grounded to the common ground and 12 volts is from either the cig lighter or cd player.
now my temp guage jumps 5 degrees when the ignition is truned to on from accessory, 5 degrees with my blower motor, and 7+ with my lights. so all together 12-15 deg higher than it should read when driving at night with the heater on. why is this, is there a better way to wire this guage up?
i have it grounded to the common ground and 12 volts is from either the cig lighter or cd player.
now my temp guage jumps 5 degrees when the ignition is truned to on from accessory, 5 degrees with my blower motor, and 7+ with my lights. so all together 12-15 deg higher than it should read when driving at night with the heater on. why is this, is there a better way to wire this guage up?
05-02-07, 09:43 AM
#5
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For power they're all as good as one another, as gauges draw very little current. For ground you don't tap into anything, you fix the wire to the chassis or to metal bolted to the chassis.
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05-04-07, 02:09 AM
#9
Lives on the Forum
Oh, you want the unabridged version?
Alrighty then...
Most electronic gauges use a simple thermistor as a sensor, and "reads" off voltage off the feedback.
This voltage is typically not regulated.
So, it's at the mercy of your electric and / or ground system.
You have fluctuations in either the electrical power or bad grounding, and the signal fluctuates like you seen.
My SPI water temp gauge does this - it changes up to 10F depending on electrical load.
Ensuring good grounds will minimize this phenomenon, but I doubt it will totally eliminate it.
So, short of stuffing a power regulator onto your gauges / sensors and running isolated wiring, you basically just gotta live with it.
-Ted
Alrighty then...
Most electronic gauges use a simple thermistor as a sensor, and "reads" off voltage off the feedback.
This voltage is typically not regulated.
So, it's at the mercy of your electric and / or ground system.
You have fluctuations in either the electrical power or bad grounding, and the signal fluctuates like you seen.
My SPI water temp gauge does this - it changes up to 10F depending on electrical load.
Ensuring good grounds will minimize this phenomenon, but I doubt it will totally eliminate it.
So, short of stuffing a power regulator onto your gauges / sensors and running isolated wiring, you basically just gotta live with it.
-Ted
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