1992 Chevrolet Other tachometer

Tiny
JO0508
  • MEMBER
  • 1992 CHEVROLET
  • 7.4L
  • V8
  • 2WD
  • AUTOMATIC
  • 43,000 MILES
I hooked up a tach to my 454 big block last night and the strangest thing happened.I hooked every wire correctly only thing I didnt hook up was the tach signal.I figured I would get at least some light to alluminate from the gauge for a test that I was getting power. When I started the engine the mph gauge started to climb and I started to smell the gauge. When I went to shut the engine down it wouldnt stop running even after I turned the key off. Finnally after about four or five seconds it shut off. The gauge had four wires, yellow, red, orange, and green. The yellow wire went to constant power which I hooked to the battery and the red wire went to switched power which I hooked to the fuse in the dash that was marked alt. The orange was optional and the green I left unhooked.
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Monday, June 30th, 2014 AT 9:25 PM

9 Replies

Tiny
HMAC300
  • EXPERT
How about the ground wire which should be black find it and hook it up if you haven't damaged stuff already
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Tuesday, July 1st, 2014 AT 6:22 AM
Tiny
JO0508
  • MEMBER
I forgot to add that.I did hookup the ground as well.
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Tuesday, July 1st, 2014 AT 2:34 PM
Tiny
HMAC300
  • EXPERT
If that is all you did then something wasn't hooked up correctly or the wiring schematic is wrong. Recheck everything again and look fo rbare spots or a wire problem.
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Tuesday, July 1st, 2014 AT 3:16 PM
Tiny
JO0508
  • MEMBER
Do you thitithad anything to do with hooking to the although fusr
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Wednesday, July 2nd, 2014 AT 12:29 PM
Tiny
HMAC300
  • EXPERT
If you have the correct schematic or let me know what kind of tach it is maybe I can find the instructions for it. And let you know what to hook up. I think it was hooked up incorrectly and did cause your problem.
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Wednesday, July 2nd, 2014 AT 12:31 PM
Tiny
JO0508
  • MEMBER
It was a glowshift tachometer.I wired it according to the instructions that came with the tach.I think what created the problem was where I wired the swiched power to the alternator fuse in the fuse panel.I also have a vacuum gauge that I got from glowshift. When I wired it up it worked fine and the only thing I did different was instead of hooking the swiched power to the alt. Fuse I hooked it to the radio fuse. It powered and lit up fine and did not create the engine problem as I had with the tach. Do you think it is possible hooking to the alt fuse made it somehow back fed the ignition system through the gauge and it kept the engine running till the high amperage burnt out the gauge and killed the back feed and killed the ignition?
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Wednesday, July 2nd, 2014 AT 3:41 PM
Tiny
HMAC300
  • EXPERT
Yes more than likely
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Wednesday, July 2nd, 2014 AT 3:42 PM
Tiny
JO0508
  • MEMBER
What would be the difference between the radio fuse and the alt. Fuse. Isnt the alt. Fuse a 12v swiched current.
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Wednesday, July 2nd, 2014 AT 3:51 PM
Tiny
HMAC300
  • EXPERT
One you didn't say what model this is so it could be different but an alternator has fusible links and they aren't meant to carry that kind of power. Fuses are I haveno further comments/suggestions.
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Wednesday, July 2nd, 2014 AT 3:56 PM

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