Electrical help (1 Viewer)

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I was working on my '77 today and accidently touched one of the bolts on the back of the alternator to the alt case itself. It wasn't the post that the white and blue wire is fastened to. It was a stud sticking out the back that actually holds the alt together. Got a little spark, no big deal.

Now my fuel and temp gauge do not work. Is there a fast blow fuse or anything I can look for besides the fuse panel? I haven't checked the fuse panel yet because I figured if a gauge fuse was blown none of the gauges would work. The oil pressure gauge works fine and I think the ammeter is working. Hard to tell. Thanks, Matt
 
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I will say that a direct short at the sending unit should indicate a "full" tank. However you may want to double check the connections at the sending unit and temp. sensor and at the cluster. Also check your grounds. I had something similar ended being a poor connections at two different places. Hopefully nothing fried. Good Luck. :)
 
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The only post that is "hot" on the alternator with the key off is the B+ with the big white/blue stripe wire. This one doesn't make much sense.

The oil, fuel and temp gauges all get power from the same circuit, so since the oil pressure gauge works the fuse is not the problem. Unless there is a wire broken somewhere under the dash (unlikely) it is more likely that the senders aren't working. Check for voltage at the sender end of the wire to confirm. This is unlikely to be related to your alternator experience even if you did momentarily ground the B+.
 

Trollhole

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Well I had the same problem with my temp and fuel. It ended up being a burnt wire on top of the fuel guage in the instument cluster. It about drove me crazy finding the source. I resoldered and it has been working fine. You might take your instument cluster apart and give it a look. And while you are in there take the covers off the lights. It's a good mod.
 
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This is sure to be the worst help ever offered but... I had a similar problem with headlights not working and alternator that was going bad. My temp and fuel gauges also quit working. I couldn't figure it out and after getting sidetracked on some other cruiser projects a week or so later it mysteriously fixed itself. Might have been related to other elec things I messed with. Moral of story, forget it and it may come back on its own. Same trick works for dripping faucets after a year or so... ;)
 
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It makes more sense that the gauge problem is due to a bad power distribution connection in the instrument cluster from the fuse block between the oil (which works) and the other two that don't work. Otherwise, both gauges or senders would have to be bad coincidentally. However, checking for voltage at the sender end (ith the wire disconnected) is easier than digging into your dash. Check first and if there is no power, remove the dash, dig in and start looking for voltage on the other end of the wire. They are color coded to make them easy to identify.
 
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Their working!! I think it mave have been the power distribution. I took the cluster out to check the gauges. All appeared okay. I checked the round cluster plug and all the connections showed power. Even the fuel gauge connection showed power, the bulb was dimer than the rest as it should be. I plugged it back in and they started working.
 
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It would probably be a good idea to clean the connections or the problem might crop up again. Corroded/weak contacts are a common problem.
 

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