Testing Gauges

[Thunderscrash 10]

I recently pulled the non working (non tach :( )gauge cluster out of my car and it appears that the printed circuit board on the back is damaged. Is there anyway I can test the individual gauges to make sure they work before I try to replace the circuit board? The gauges appear to be in good shape and all but they never worked since I bought the car. Although the fuel gauge does work, that's the only one. I'd like to at least get the speedo working I plan to put in some mechanical gauges for oil pressure and water temp.

[jag 10]

What do you mean by damaged? If the copper conductors on the PCB are cut or broke you can bridge those gaps with solder (small cuts or breaks or 22 ga wire for larger breaks)

 

JAG

[Thunderscrash 10]

Te printed circuit is coming apart. Some of the wiring is coming up off the board and the wires don't appear to be broken but I'm not completely sure. Ill try to post some pictures of it later tonight.

[70mstang 11]

You can use a resistance meter to check for continuity. All of the grounds tie together and you can trace from beginning to end of each circuit. They sell replacements in all of the major parts catalogs if you find issues.

 

This link is to youtube .. Moss motors where they explain how to test guages out of the car.

 

 

There are other videos as well, but gives a good example of how to test.

[Nightowl 10]

I got voice off of that link but no video. It is just a green screen.:angry:

[Thunderscrash 10]

Thanks for that video. I took some pictures of the circuit board and ill try to post them up later. It's in really rough shape it doesn't look like the wire is broken anywhere but it's falling apart and just looks real bad. I am going to buy the replacement from cj's because it seems to be the cheapest but I am going to try to test the gauges first. I mean if the gauges are bad then I'm just going to start looking for a new cluster. I've just been real busy this past week or so I haven't had much time to do anything.

[danno 128]

The gauges themselves are almost bulletproof. I have never heard of one going bad, it is always the wires, circuit board, or something else.

 

First of all, the speedometer has nothing to do with the gauges. If it does not work, it is a mechanical issue and is completely unrelated to the gauges.

 

Second, do NOT expect the ampmeter to work. They never worked, even when brand new from the factory.

 

If you fuel gauge works, your voltage regulator on the circuit card is ok. You can test the gauges when they are out of the car. Follow the trace on the circuit card from where it goes from the voltage regulator to the 16 pin connector. Connect +12 volts up to this with a jumper wire. Connect the negative part of the screw that mounts the regulator.

 

Then follow the trace that goes from the temp gauge to the 16 pin connector. Connect a jumper wire between this trace and the minus of the 12 volt supply, and you should see the meter start moving up right away. It will only take a second or so to go to maximum. DO NOT leave this jumper connected for more than 2 or 3 seconds.

 

After you do the temp gauge, do the oil pressure gauge the same way. Follow the trace from the gauge to the connector, and jumper the trace connection at the connector to minus 12 volts. You will see the oil gauge move immediately. Again, do not make this connection for more than 2 oo3 seconds!!!!

[Thunderscrash 10]

Here is the link to my photobucket account I can't get this pictures to load on here. Let me know what you think they aren't the best shots but I think you get the point.

 

http://s1112.photobucket.com/albums/k483/thunderscrash/Mobile%20Uploads/

[MustangChuck 16]

Is it possible to bench test the gauges outside of the car? I have all of the wiring out of my car and the gauges set aside. I want to test them before I start reassembling the car to know which are bad (most of my gauges didn't work when the car ran) and which really need replacing. Some of them have been under water for a while and are most likely ruined. I just want to verify.

 

Thanks,

Chuck

[etel64 10]

Water? to be a smart a**, they dont so well that way. no really though. chances of you resurecting them and then actually working is slim. Even if they do work for a bit, they wont last long. Im figuring these are the original 43 yo gauges with regular use where there is humidty that attacks them through the years. Now submersing them is a whole nother story.

[MustangChuck 16]

Probably, but I still want to give them a test. I have two complete sets (got lucky on eBay one day and bought a complete gauge cluster with bezel for like $30 long before I knew I would need it -- just too cheap to pass up). The only problem is that I had the fuel gauge sitting in the car when the storm hit. I want to give them both a try to see if they work or if I need to start searching for a replacement (or saving for a complete set of new gauges).

 

The speedometer should work, since it's mechanical. The rest I would like to bench test to verify.

 

Thanks,

Chuck

[etel64 10]

MC, here is my story with my gauges. they didnt work after I replaced everything that powers them(VR,ribbon). so I took them out and started doing some testing. Remember, these do not get full voltage!!! they run on 5vdc. so I taped (2) "D" size batteries together and connected them to each gauge. apparently the gauges had been sitting so long they needed the max 5vdc to come off the bottom position that they where stuck on. hope this helps.

[MustangChuck 16]

Many thanks! I knew they didn't get full voltage, I just didn't know how much they got. I'll give your suggestion a try with the info from a link posted earlier in this thread.

 

Chuck

[danno 128]

Etel's idea will work fine, I think. But be careful with the polarity. If you do not start to see the meter move right away, change the plus and minus wires around. Also, do not leave it on for more than a few seconds. Even though it is only 3 volts ( from 2 batteries) it still can ruin your gauge if left on for too long.

 

And about the water and rain, I think you could be OK. It is all plastic, there is nothing to rust except a few pieces inside that should not matter. The odds are you will still need to take it all apart and clean the parts real good, but this can be done. You should be able to disassemble it all the way to the movement, it will take some patience and fine tweeking to do it. I have done it, I know it can be done.

 

And do not test the ampmeter by the method mentioned. It does not work anyway, and this method could fry it.

 

My experiences with my own gauges and helping friends is that problems are almost never with the gauges. It is always with the regulator, flextape, connectors, and wires.