HELP!!! 1975 Dash Problem.
Thread Starter
|
New User
Joined: Sep 2009
Posts: 3
Likes: 0
HELP!!! 1975 Dash Problem.
Anyone know why my fuel gauge and temp Gauges would be reading to the left? I have been chasing this electrical monster for over two weeks now and am going crazy. Just got my turn signals and alt and high beam lights to work today and I have traced all the wires and have checked them all. I have replaced the voltage reg now also. Driving me crazy. Need some help please.
New User
Joined: Jun 2007
Posts: 12
Likes: 0
From: Cut Bank, Montana
Probably the oil pressure gauge as well. There is a voltage regulator on the back of the instrument panel that these three gauges use. It is small and rectangular, plugs in like a 9V battery. That is the most likely culprit.
New User
Joined: Jun 2007
Posts: 12
Likes: 0
From: Cut Bank, Montana
Not sure on the main regulator. Did you use a new or used one on the instument panel? I've had lots of used ones from parts yards that were inaccurate as well. If you know someone with a similar truck, see if you can try theirs. Never bought a new one, so don't know if some are junk or not.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
The charging system voltage regulator (on the inner fender) has nothing to do with it. It just happens to have the same name.
These gauges read resistance. Take the fuel gauge for example - the sending unit in the tank is a variable resistor. As the fuel level goes down, the resistance in the sending unit increases, which makes the current through the fuel gauge decrease. This causes the needle to point toward the left. The temperature gauge operates on the same principle (the sending unit is also a variable resistor).
If the gauges are pointing all the way to the left, then no current is flowing through them. This can happen because they're not receiving power. I know you said you replaced the instrument cluster voltage regulator, but make sure it's actually providing power. Check the output and you should see on the order of 5 volts. The other reason this can happen is because the sending units are not properly connected to the gauges, which will open-circuit the gauges and make them read all the way to the left. Double check the wiring and that the sending units are connected. The temperature sending unit grounds by threading into the engine block, and the fuel gauge grounds near the tank.
These gauges read resistance. Take the fuel gauge for example - the sending unit in the tank is a variable resistor. As the fuel level goes down, the resistance in the sending unit increases, which makes the current through the fuel gauge decrease. This causes the needle to point toward the left. The temperature gauge operates on the same principle (the sending unit is also a variable resistor).
If the gauges are pointing all the way to the left, then no current is flowing through them. This can happen because they're not receiving power. I know you said you replaced the instrument cluster voltage regulator, but make sure it's actually providing power. Check the output and you should see on the order of 5 volts. The other reason this can happen is because the sending units are not properly connected to the gauges, which will open-circuit the gauges and make them read all the way to the left. Double check the wiring and that the sending units are connected. The temperature sending unit grounds by threading into the engine block, and the fuel gauge grounds near the tank.
Trending Topics
New User
Joined: Jun 2007
Posts: 12
Likes: 0
From: Cut Bank, Montana
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
Posting Guru
Joined: Mar 2009
Posts: 1,427
Likes: 1
From: Huntington WV
are there any lights or anything else acting up on the dash besides these gauges? An what was you doing when it started acting up? Did you change anything out on the truck before the problem started?
Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
Best bet, is to get a used "Factory" one out of the wrecking yard, or bite the bullit and buy one from Ford if you still can do so.
The ICVR has to have a good ground connection. The ICVR is bolted to the printed circut using a bolt headed screw. You can add a ground wire to this mounting bolt, and ground the other end to clean dash metal to insure a good ground.
The ICVR also has a place where you can adjust them to regulate how high or low the gauges read by turning the adjustment. I do not recommend using the adjustment unless you know what you are doing, as this can totally make your gauges read out of whack if you do it wrong. Do a search on the website for ICVR adjustment.
Senior User
Joined: Jan 2010
Posts: 267
Likes: 0
From: Western Kentucky
have you tried changing the temperature switch and the fuel sending unit?
I believe they could be the culprit.... if the temperature switch is bad the vehicle may experience inaccurate temperature gauge function, overheating engine, internal engine damage and/or excessive fuel consumption. About $7.00 at Auto Zone
And if the fuel sending unit is bad, the fuel gauge may not work properly, and this is a problem Ive dealt with recently. Even though I got one off my dad he had saved just in case his truck needed it, at Auto Zone about $65.00
I believe they could be the culprit.... if the temperature switch is bad the vehicle may experience inaccurate temperature gauge function, overheating engine, internal engine damage and/or excessive fuel consumption. About $7.00 at Auto Zone
And if the fuel sending unit is bad, the fuel gauge may not work properly, and this is a problem Ive dealt with recently. Even though I got one off my dad he had saved just in case his truck needed it, at Auto Zone about $65.00
Thread
Thread Starter
Forum
Replies
Last Post
tnwalker01
1997 - 2006 Expedition & Navigator
3
Jul 16, 2012 02:12 PM
