I removed my entire gage luster hoping to test the fuel and volt gauge. I've tried using a 9 volt battery on the pins but no luck. does anybody have a suggestion as to how to test these directly?

 

i believe the fuel level sensor is just a resistor.

 

The FSM has procedures for testing the gauges. I think the section is BODY ELECTRICAL.

Just what is wrong with the gauges right now?

For the gauge they just install a resistor of a fixed value in a given pin at the fuel pump connector and read the gauge. They use a Mazda tester but you don't need that. Just look at the picture they give which shows what the gauge should read using different resistors.

All they do with the voltmeter is put a meter on the batt posts and start the engine. They compare the gauge in the car with the meter on the batt posts. They recommend r square the sucker if it does not agree with the meter reading on the batt posts. A little radical imho.

 

I belie the gauge itself is at fault cause it is not moving at all if I ground the fuel level sensor. I've seen that page from the FSM but I would like to test the movement of the gauge.

 

Well I don't have a spare cluster to work on, but it seems that if you look at the jpg attached you could put batt voltage on what is referred to as A2 and put the ground to A1 and the meter should read whatever the batt voltage is. I'd use the car battery as the power source.

Some threads on this site mention the screws on the back of the meter/cluster as being the problem. If memory serves the screws are what make contact b/t the meter and the circuit board traces.

Seems fuel would be A2 for pos and B3 for the gnd for the fuel. Sort of a momentary touch of the neg to see if the gauge needle will move at all. I wouldn't want to peg the needle.

That's for a series four car. Series five might differ. The wire colors should match what is shown on the second jpg. Like A2 is black/yellow or B/Y to get you started. Powers all the gauges I believe. A1 should be black but on early 86-86 might be brown/black.

 

I appreciate the help.
I did tare the cluster apart and noticed exactly what you were saying above, the screws holding the gages while at the same time providing connection had rusted heads. I wonder if moisture is to blame. When I get home I will try using the car battery for testing, so far I've been using a 9 volt battery and I tried a 12 V power adapter without any luck.