Help with how circuit board works

[keith88]

My gas gauge worked on occasion when i didn't i would pound on the face of it and it work for a while. When i took out my dash i found lose pins on the board that made them work,I have a mechanical temp and oil gauge so that's not a big issue but my gas is. I tried to bypass the pins by splicing into the wire for the gas and going directly to the gas gauge but it did not work I also tried to solder the pins that didn't work so I tried to glue them in place that didn't work. So it looks like i will need another board. That being said i noticed since that nothing attached to that board is working now not even the lights can any tell me how the board is set up or how it works thinking one cant by pass those at all.

[BLK 68 R/T]

When you spliced the wire. How did you do it exactly? Possible you backfed with a full 12 volts and fried the voltage limiter and damaged the other gauges. The gauges work on a 0 to 5 volts scale.

[keith88]

I used a splice connector that went though the wire than connected the other end to the post on the gas gauge that the pin went to.

[keith88]

Where the pin goes on the board ,is that the positive or the negative side ? you can see a connection going from the pin to one side of the gauge connection on the board its self the other side seems to come out of the regulator that goes all the other gauges and lights.

[BLK 68 R/T]

I will have to check in the fsm to get exactly how the gas gauge wiring is routed. That being said, it sounds like you need to pull the instrument voltage limiter out and see if it is still good. Will try and look tonight at the wiring diagrams to check what goes where.

[BLK 68 R/T]

Okay, so on the pin connections, 2nd one in, black, that is the 12 volt feed to the voltage limiter. Dark blue wire goes to the fuel tank sending unit. With everything connected you should be able to measure for the 12 volts incoming on the black wire which goes to the vertical position tab on the voltage limiter. You should have roughly 5 volts coming out of the bottom horizontal position tab. Report back with what you find.

[keith88]

At the moment the dash is back in so i still can drive it but I have found a picture of the board and have marked in black the pin and connection that i by passed to. Would you know if that would be the pos or neg side of the gauge that the  gas gauge side attaches to, might of feed the wrong side to start with so i might not of killed the limiter.

[Charge_her]

Any chance you guys could post the diagram and or picture of the board / pins? My gas gauge is inconsistent too.

[keith88]

The picture of the board with pins is above the black line is to the pin that goes to the gas the one to the left is temp and left of that is oil. To the right of the gas pin is apparently power to the limiter and right of that would be the lights.

[BLK 68 R/T]

At the moment the dash is back in so i still can drive it but I have found a picture of the board and have marked in black the pin and connection that i by passed to. Would you know if that would be the pos or neg side of the gauge that the  gas gauge side attaches to, might of feed the wrong side to start with so i might not of killed the limiter.

By re-reading your first post and looking at the pictures some more. I don't believe you bypassed the pins in a way that would damage anything. By you having to bang on the dash to make stuff work tells me a few things, either you have a loose connection, bad ground on the gauge cluster or a combination of both. I would start by verifying the voltage limiter is good, make sure it fits snug into the circuit board - bend the tabs a little if needed, verify you have a good ground connection from the gauge cluster housing to dash frame and that your dash frame has a good ground to the body. You have already soldered the pins correct? just need to make sure that the solder is not excessive either which could cause stuff to be shorted together.

[keith88]

No the solder didn't not work it would not take so I tried to glue the pins with JB weld... don't think that worked either. My plan is to buy another circuit board but i have to wait a bit seeing my wife just lost her job until things work there way out. I was wounding which side is which on the board  is the pos and neg I know the pins were lose and that's why it would work when i hit it. More than likely i glued it not making a connection but the lights in the board also now don't work so i messed something up.

[BLK 68 R/T]

Sorry to hear about your wife loosing her job. Hopefully thing work out well and you will be able to purchase a new circuit board.