Gas 70-Series Tachometers

[AirheadNut]

Does anyone know what type of input the gas powered 70 series tachometers use? I've discovered that the factory tach in my LJ78 uses a magnetic impulse type signal that isn't compatible with the square wave type signal generated by my VW ECU. I know that the tachometers in 1st and 2nd generation 4Runners and Pickups are pretty much plug and play with the VW signal, and was thinking that maybe the FJ7x or RJ7x tachometers might work too, and fit in my dash.

Do they just receive their signal from the coil like a conventional older tachometer? 4 or 6 cylinder shouldn't be an issue, as I can correct the input with a resistor or potentiometer to match the engine.

 

[roscoFJ73]

I think it comes from the alternator, at least with the 3F

 

[AirheadNut]

Ah, interesting. So a signal converter may be necessary even with an FJ70 tachometer.

 

[roscoFJ73]

I dont know much about. When I went from a 3F to a 1HZ I got an auto electrician in and he said the alternator provided the signal to the 3F, so he gave me a wire to connect to the injection pump.

Another auto electrician told me he knew of a place where the original gauge could be modified to accept any signal.

 

[JohnnyOshow22]

Did you ever figure this out? I am dealing with the same issue

 

[AirheadNut]

Did you ever figure this out? I am dealing with the same issue

Unfortunately not. I had a lead on a tach from an FJ75 but I wasn't able to get it. The tachometer is now one of the back burner projects, though I'm still on the lookout for a working FJ or RJ unit that I can try out. I wish I had been able to hook an oscilloscope up to the original 2L-TE ECU and figure out what kind of signal it put out, then possibly make a signal converter for it.

 

[OGBeno]

Did you ever figure this out? I am dealing with the same issue

Johnny: What year is the 70 you are working on? Newer tachometers are still available from Toyota depending on what year the truck is.

 

[JohnnyOshow22]

Johnny: What year is the 70 you are working on? Newer tachometers are still available from Toyota depending on what year the truck is.

Onur, pm'd you thanks!

@AirheadNut thanks for the update, hopefully we meet at a 406 cruisers gig sometime!