Voltage gauge, Need help
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Senior User
Joined: Oct 2015
Posts: 283
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From: Franklinton, NC
Voltage gauge, Need help
So my 1984 f150 had idiot lights, I switched to a digital dash. I dont like the wiring and had fears of a fire so I am looking for Deutsch connectors. Until then I put in a dash that has gauges for all (fuel,oil,temp,batt)
The issue and I dont know if this is normal:
With the key on no cranking, my gauge pegs out at "C"
with the Key off It goes in the middle of "D" and "C"
Now with the digital guage it will read 11.9 at the battery (Fuel pump priming)
with this cluster and a volt meter it reads 12.1 at the battery
With the cluster unplugged I get 12.53 at the battery
I cannot crank it as the distributor is out.
Is it suppose to peg out to c before cranking?
Why the .43 voltage drop?
testing the cluster wires for continuity to ground (Key off) I got the following tone hits:
Black:Ground
Blue Red: Instrument Lights
Red green: Ignition switch
Red Yellow: Cigar lighter
White Blue: Right Turn signal
Green /Light green: Seat belt warning buzzer.
Can someone guide me?
Thanks
The issue and I dont know if this is normal:
With the key on no cranking, my gauge pegs out at "C"
with the Key off It goes in the middle of "D" and "C"
Now with the digital guage it will read 11.9 at the battery (Fuel pump priming)
with this cluster and a volt meter it reads 12.1 at the battery
With the cluster unplugged I get 12.53 at the battery
I cannot crank it as the distributor is out.
Is it suppose to peg out to c before cranking?
Why the .43 voltage drop?
testing the cluster wires for continuity to ground (Key off) I got the following tone hits:
Black:Ground
Blue Red: Instrument Lights
Red green: Ignition switch
Red Yellow: Cigar lighter
White Blue: Right Turn signal
Green /Light green: Seat belt warning buzzer.
Can someone guide me?
Thanks
Thread Starter
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Senior User
Joined: Oct 2015
Posts: 283
Likes: 2
From: Franklinton, NC
I have traced the drop to the following wires. The green red wire (excites the alternator) and white blue.
Key on volts read 12.1 with everything hooked up
When the green/red wire is removed (key on) the voltage is 12.32
Key off 12.55
with green red and white blue removed it reads 12.48
The alternator is a 3g alternator. Is it suppose to have that much of a drop?
How is the white blue causing the drop (faulty multifunction switch?)
Key on volts read 12.1 with everything hooked up
When the green/red wire is removed (key on) the voltage is 12.32
Key off 12.55
with green red and white blue removed it reads 12.48
The alternator is a 3g alternator. Is it suppose to have that much of a drop?
How is the white blue causing the drop (faulty multifunction switch?)
Cargo Master
Joined: Mar 2008
Posts: 2,567
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From: Washington
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The green/red to the alternator tells the alternator regulator inside it(or outside it if you have the old type) to come "online" and get ready to charge. This puts voltage on the field windings which causes a draw on the battery. That's the reason for the key-on wire to the alternator, so when you turn the key off it doesn't drain the battery with the engine off.
Those voltages you are reading are what they call a "surface charge" on the battery, over and above 12 volts. Very easy to get rid of that and have it drop down when you put a small load on the battery. Don't worry about it unless you get much below 12v.
Those voltages you are reading are what they call a "surface charge" on the battery, over and above 12 volts. Very easy to get rid of that and have it drop down when you put a small load on the battery. Don't worry about it unless you get much below 12v.
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