When I bought my pickup 5 years ago, the tachometer more or less worked, and then it sometimes worked, and then it sometimes worked when I turned on the heat or did some other random switch/electrical-related function, and now it hasn't probably worked in the last year. I don't really need it, but I like things to work and I've been imaging it might be an easy fix. I started to look into it, looked at my wiring diagram, checked the fuse, and realized I don't even know what a tach looks like. I have a speedy tach that I wrap around the first spark plug wire when tuning the carb, but I've realized I don't know what the tach look likes that sends into to the tachometer. That said, I don't have a tach tester, which I imagine is what you plug into one of these green plugs around the ignition coil?

Where is my tach located and what does it look like? Any suggestions? I started looking at my ignition coil, and I realized there is a lot of stuff coming off around there that I don't know of either. For the fun of it, does anyone know what these green plugs are for, two of which have a cap and one it not capped? The second picture is the picture of the green plug that you can see behind the ignition coil in the first photo.

Also, I just realized that the orientation of the photos below might be a bit confusing - to confirm, my ignition coil is on the drivers side.
1982 toyota pickup 22r

Thanks!


the green plug that is in the far left of the first photo.

 

nicolodi,

The tach (short for tachometer) is not a physical or mechanical item that exists in the engine bay. Your tachometer (what is on your instrument cluster) takes an electrical signal sent from the ignition system (in this case coil/igniter) and converts it into an RPM display on the instrument cluster. On my 83, the uncapped plug (on the right in your picture) has a yellow wire and connects to a male plug also with a yellow wire. This in turn goes to the tachometer on the dash. I suspect that the reason that you tachometer hasn't been functional is that this plug appears to have been disconnected. The capped plug next to the aforementioned plug is for attaching an external tachometer for diagnostic purposes. I'm not sure what is going on with that plug on the left (with red tape on it?) but I imagine it may be different than my 83. Perhaps someone with an 82 can chime in. Also, it looks as if you have another plug with a black wire hiding under the plug with the brown wire. It seems that perhaps this one is also disconnected? Maybe it goes to the yellow empty plug? On the 82s did the yellow wire go to black? Or did some previous owner perhaps do some wiring repair and replace the yellow wire with black? Food for thought.

Hope this helps,

Sam

 

Wow, good spot on the hidden black plug beneath the brown. I'm not sure how that became unplugged from the yellow, but simply plugging that into the yellow did the trick and the tach works again now. A good doh moment. Anyways, thanks for the help! It's cool to know more about how the tach works and the things coming off the ignition coil. Perhaps one day I'll have reason to find out what is up with the plug on the left with the red tape.

 

Glad to hear that worked out. Are the connectors in good shape? Overtime they tend to get brittle and their little locking tabs can break off. If the tabs break off they can eventually rattle loose from the vibration in these old trucks. If that is the case you can always throw a little electrical tape or a zip tie on there and that'll usually hold it together. As far as the plug on the left goes, on my CA 83 there is one that is capped off but it is much larger and has four wires going to it. One red, one brown, one white, and one green with a red stripe. This plug is also just for diagnostic testing. Perhaps the plug on your 82 is for a similar purpose.

Sam