Hi Everyone!!

I have a 1983 Ford half ton truck 2wd and I've been having problems with my instrument panel gauges? All my gauges are needle gauges and not warning lights. The fuel gauge and sometimes the battery amp gauge will all of a sudden move irradically to one side(right)then return to its normal position?? Could the instrument voltage regulator/voltage stabilizer be the cause of all this and if so where is it located?? In regards to my fuel gauge could the float in the gas tank be at fault and causing false readings?? Are there websites that show a diagram of the location of this unit(instrument voltage regulator) and how to replace it with a new one? Thank-you!!

 

Instrument Voltage Regulator is mounted on the back of the instrument cluster; you have to pull the Bezel (trim) and the cluster to get at it. It's a little rectangular metal box looking thing with two electrical terminals that mate with the Printed Wiring and mounts with one screw (also the ground connection). The regulator provides a regulated 5 Volts (pulsating) for operation of the Oil, Temperature and Fuel gauge circuits (gauges and sending units). Usually, if the regulator is at fault, all three gauge circuits will show the same symptoms (i.e., too low, too high, erratic, etc.). The Ammeter circuit is completely seperate and is not connected to the regulator. Fuel sending units quite often wear out, they are resistance wire wound on a form with a sliding contact actuated by the float. Bad Sending Units can cause a variety of symptoms including Empty or erratic readings. Floats are sealed metallic cans (in most cases) and can rust/corrode to the point they get holes and fill (or partially fill) with fuel causing empty or low readings.

 

it could be that the guage is working fine, and that you have a fault in the charging circut, Voltage regulator or altenator.

 

Here's one off a 70's truck.



the common problem is corrosion.

The system is being outright grounded and un-grounded rapidly.

a direct positive "Ground Out" causes Gauges "To PIN".

It is the sending units of these systems that has a 'controlled grounding' feature that regulates the measurement of the gauge.

Removal and a thorough cleaning of all connections of the cluster and verifying a secure ground will usually eliminate the problem you are having.

There is also a spray on corrosion preventative for electrical units that is available at marine shops.

It is called: Corrblock

 

The 80's trucks look identical. Infact the engineering behind the instrument cluster is exactly the same as the 70's. Just they have been redesigned and circuts moved about a bit.


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The ammeter on my truck is defective in a certain way.

Every time I hit a bump, the ammeter will bounce to the right or to the left, before actually reading acurate. There is a little stabliser spring that is broke in my ammeter. It reads accurate untill I hit a bump. Need to replace that one day.

You didn't hit a large hole just before the ammeter went wacky did you?

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And piffery1 is correct, the ammeter isn't connected to the instrument cluster voltage regulator.

The ammeter isn't grounded either.

The D side is hooked closer to the altenator, and the C side is hooked closer to the battery in the same wire the altenator uses to charge the battery, and for battery power to feed back through when needed. The two wires from the ammeter are seperated with a shunt inbetween them.

When the altenator is charging a lot. the ammeter will read farther to the C side.

If you are using more battery power than you are charging, the ammeter will read over to the D side.

If your voltage regulator is having problems keeping up with the constant changing demands and voltage differences it could manifest itself as a fluctuation on your ammeter.


You should always see a slight fluctuation on the ammeter due to idling, or to crusing etc, or power demand. At Idle the ammeter should read up and down, or a little bit to the D side depending on what accessories are being used at the time. If your turn signal is on, you should see the needle move as it blinks. While crusing the needle should be just right of the up or down position on the C side. Air conditioning, or heater on will move the needle even more right etc..

If your battery is dead, with the engine is running, the guage should move over to the C side. On my ammeter it would go inbetween the half mark and the C mark. A very high charge reading.

If your voltage regulator, or altenator quits working, the guage should move over to the D side. On mine it will read between the half mark and the D mark.


edit: If both your Fuel guage and ammeter are showing simular problems, I would guess you have a crossed circut between your fuel and ammeter guages, in the harness somewhere. They should not be connected, or have a common problem between them.


Hope this rambling helps.

 

There is a big ground wire that grounds the cab frame to the engine block. It is located close to where the accellerator cable comes thru the firewall. It often corrodes, and/or gets loose at either the firewall or the engine block... This wire will easily cause your gauges to read excessively high, or low. My 83 plagued its previous owner for years and had him thinking it was overheating constantly. When I got it, it came with a new radiator, water pump, thermostat, and temp sending unit. It still showed overheating. I fixed the ground, and the problem was cured.

 

The link wasn;t worling when I posted earlier.

here it is now.

http://www.corrosion-control.com/corrblock.html

I would recommend all DIY'ers get a can of this for clusters & loosening up a corroded distributor.