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03-03-2007, 06:09 PM
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#1 |
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Junior Member
Join Date: Feb 2005
Location: topeka, kansas
Posts: 258
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Gas Gauge - Constant 12v?
Is the gas gauge supposed to be connected to a constant 12v source, or is it supposed to be only hot when the key is on? Something is running my battery down on a regular basis. I've disconnected everything I can find, but the primary drain seems to be the gas gauge. Should it only be on when the key is on?
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_______________________________________ 62 SWB BBW (under construction) 86 Vette Convertible |
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03-03-2007, 08:14 PM
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#2 |
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Senior Member
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
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Re: Gas Gauge - Constant 12v?
The gas gauge is only powered when the ignition switch is on. I would suspect the alternator or regulator.
Jim
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1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC |
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03-03-2007, 08:18 PM
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#3 |
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Is a bullfrog waterproof?
Join Date: Nov 2000
Location: OLATHE, KANSAS
Posts: 1,130
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Re: Gas Gauge - Constant 12v?
 
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"It is better to remain silent and be thought a fool, than to open one's mouth and remove all doubt." Ben Franklin __________________ 1970 Chevy shortbed 2002 Harley Custom Chopper (Long sucker) 1998 K2500 5.7L 5-speed Longbed 1st two are My son's toys...they just live in my garage! 1997 GMC K1500 Suburban 1993 S-10 Blazer 4D (youngest son's daily driver) 2000 Dodge Ram 4WD Ext. Cab (5.9L) Wife is a late year 1951 |
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03-03-2007, 09:21 PM
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#4 |
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Junior Member
Join Date: Feb 2005
Location: topeka, kansas
Posts: 258
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Re: Gas Gauge - Constant 12v?
right but.. the battery only runs down when it's sitting for several days. As long as I drive it daily, no problem so the battery is getting charged. Battery is new, alternator is new. Voltage reg is old.
When I pull the battery cable off there's a spark, so something is drawing power. I started pulling fusses and it finally quit sparking when I disconnected the fuel gauge.
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_______________________________________ 62 SWB BBW (under construction) 86 Vette Convertible Last edited by 53lowdown; 03-03-2007 at 09:23 PM. |
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03-03-2007, 10:05 PM
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#5 |
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Registered User
Join Date: May 2003
Location: Englewood, CO
Posts: 146
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Re: Gas Gauge - Constant 12v?
fuel gauge should be ignition on power.
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03-04-2007, 06:39 AM
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#6 |
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Senior Member
Join Date: Jul 2001
Location: Muskegon,MI,USA
Posts: 6,026
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Re: Gas Gauge - Constant 12v?
Where are you disconnecting the fuel gauge at?
Is there any chance that the brown wire from the tank sending unit is plugged into the wrong terminal on the fuse panel? The gas gauge is powered off of the ignition so there must be a wiring problem. Here is a picture of the labeled fuse panel just in case yours is not readable. Jim
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1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC |
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03-04-2007, 11:11 AM
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#7 |
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Junior Member
Join Date: Feb 2005
Location: topeka, kansas
Posts: 258
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Re: Gas Gauge - Constant 12v?
When I test the voltage on the fuse panel on the post that says 'Fuel Gauge' it reads bout 8 volts - probably because the tank is ~3/4 full? With all the fuses out, the battery still sparks on disconnect. When I disconect that Fuel Gauge post, it quits sparking. I guess I'll pull the instrument cluster out and connect the gauge to ingition source.
One last question though - Is the fuel gauge supposed to move when the key is switched off/on? Mine stays constant so it must be attached to a constant source.
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_______________________________________ 62 SWB BBW (under construction) 86 Vette Convertible |
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03-04-2007, 01:30 PM
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#8 | |||
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Union Electrician
Join Date: Feb 2005
Location: Louisville, Ky.
Posts: 3,356
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Re: Gas Gauge - Constant 12v?
The fuel gauge should only move with the ignition on, although they generally hold their position unlike the temp and ammeter.
I do not think you should have voltage on that plug, is the wire you are unhooking light brown or beige? That is the sending unit wire and all it does is relay a signal to the gauge, and should olny have a resistance reading. I think you have a short in the cluster harness and it is appling power to the signal side of the gauge and causing the draw, but it is just a guess. Good luck and let us know what you find.
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 69 Custom-10 SWB FLEETSIDE  350/350 TH Dropped 3.5/5.5"Help support the board->HERE Board vendors -> Vendors list Zip:40272 Big Sandy Survivor... Quote:
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03-04-2007, 09:53 PM
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#9 |
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Registered User
Join Date: Dec 2006
Location: Rhode Island
Posts: 602
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Re: Gas Gauge - Constant 12v?
If the battery runs down after a few days and it turns out not to be an appliance that's left on, I'd suspect one of the diodes is gone in the alternator's bridge rectifier, allowing current to seep back through it.
Testing the diode pack with an ohmmeter or taking the alternator to have it tested is my recommendation.
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69 C-10 SWB Fleetside 454/TH400 (For Sale) http://67-72chevytrucks.com/vboard/c...ct=1299&cat=12 70 El Camino 454 TH700 29 Model A 4-DR Sedan Deluxe |
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