Pre 84 Trucks 1st gen pickups

Help wiring Tach..

Old Dec 23, 2019 | 01:22 PM
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Help wiring Tach..

Hi guys,

I have an '82 4X4 Deluxe that I recently swapped in an SR5 gauge cluster with a tach. Thanks to 83's write up on rewiring everything to make it work, it works great but I need to run a wire for the tach.
I've searched and searched on here and some say you need to hook into the wire coming off the coil with the rubber cap. I tried that and it has a constant 12 volts when the ignition is on. All it did was make the tach constantly and slowly rise.

Now I'm lost the FSM shows a yellow wire going to the tach on SR5 Models but I'm stuck. Any help would be appreciated. Here's a few shots of what I have...




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Old Dec 23, 2019 | 01:46 PM
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Not that it helps you, but I still see this photo at the bottom of the first page of the thread.

If that doesn't work for you, I'm out of ideas!


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Old Dec 23, 2019 | 01:50 PM
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Yeah, sorry 83, I did see that it is still there. That has to be the same one as mine. Can an '83 and an '82 be that different? You just ran that wire directly to the back of the gauge cluster to the tach?
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Old Dec 23, 2019 | 02:01 PM
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I'm sure you've found all this if you're searching, but here's the link to the Marlin thread that got me started. There's some discussion in that thread on the tach wire. I googled "running a tach wire 1983 Toyota" and cllicked the "image" results. Lots to choose from in there.

Assuming you're connected to the right spot on the back of the cluster, all I can figure is that maybe the tach itself is messed up. But I wouldn't blame it just yet.

Good luck!
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Old Dec 29, 2019 | 01:27 PM
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Anyway to test the tach that you know of? The FSM does not outline how to do it..?
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Old Dec 30, 2019 | 07:58 AM
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Not that I know of...but I'm sure there is.
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Old Jan 3, 2020 | 07:03 PM
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I thought tach wires were usually black but never worked on one this old. Also think the signal is pulsed, so maybe it's something you could pick up with an analog voltmeter (similar to testing an O2 sensor output) if you're hunting for the wire. As far as testing the tach I have no idea. No resistance chks in the FSM? Maybe check a different year to give an idea? Could build a voltage pulsing circuit with relays or transistors and hook it up to that but that can get a little involved, and also need to be sure that pulses should be 12v, or whatever
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