Back to square one!
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Mountain Pass
Joined: May 2012
Posts: 186
Likes: 1
From: Voorhees NJ
Back to square one!
ok! After fixing a couple burnt ground wires after the jumping debacle, I found some more problems. Got a new tach and clock. They didn’t work when I installed them. Checked voltages and they’re good. But when I plug them in no workey!!!;also installed speedometer from donor cluster. It doesn’t work either. Any suggestions would be appreciated!!!
Moderator
Joined: Jan 2001
Posts: 57,004
Likes: 2,748
From: Virginia
Check the circuit board where the wiring plugs in. The copper can be corroded and it also can come loose from the clear plastic and get wrinkled. A little super glue to glue it back on the plastic works for me. Take your speedo head out and put it in the other cluster.
Laughing Gas
Joined: Feb 2016
Posts: 817
Likes: 27
You could check continuity of the four circuit board ribbons that support the tach.
You could clean the tach per the thread in the Stickies.
Hopefully you didn’t get a bum tach, but they’re going on forty years old.
You could clean the tach per the thread in the Stickies.
Hopefully you didn’t get a bum tach, but they’re going on forty years old.
Thread Starter
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Mountain Pass
Joined: May 2012
Posts: 186
Likes: 1
From: Voorhees NJ
Checked clock with another power source and it works fine. Forgot to mention that both clock and tach are not original to the truck. I wired in both. So now I guess I’m going to re-wire both from scratch and go from there��
Lead Driver
Joined: Jul 2009
Posts: 6,477
Likes: 19
From: Sheffield, AL
Yes. I have tested tachs with the hood open. On the back of the factory tachometer, connect 12v to "B", green wire on coil [-] to "C" and a ground wire to "G" if six cylinder and also to "8" if a V8.
Thread Starter
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Mountain Pass
Joined: May 2012
Posts: 186
Likes: 1
From: Voorhees NJ
Finally after many days and short hours, I got everything to work! I just went back and re-did all the previous grounds I had used. Cleaned up everything behind the dash instead of the rats nest that was there. Also found out that I will need to start hunting for a new printed circuit board(plastic) without the tach wiring. Undid the main molex plug so many times it pulled the copper off two spaces where it plugs in. I have a couple of the circuits that have the tach etched on it, but my tach is hard wired. Not sure if I could use one of those board because I tried once before and it didn't work the tach. Not sure if it would double feed the battery connection on my tach. Thanks to everyone that chimed in with suggestions!!!!!!!!!!!!
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Moderator
Joined: Jan 2001
Posts: 57,004
Likes: 2,748
From: Virginia
If you have a 1980, they can be a little oddball in the wiring department. I m not sure the tach cluster is plug and play like it is in the little bit later models.
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