12 volt tachometer option for 12HT?

[KeepCruzin]

Hey guys, Im doing my third 12HT swap soon, this time into my fj40, and this time I want to go fully 12volt. I already have a replacement starter, alternator, AC pump and glowscreen solution that operate on 12volts. Im assuming that a 12volt starter will have the Umffff to turn the engine over on cold days (if anyone has experience Id love to hear it).

The only remaining hurdle is the tachometer. I know its not especially critical from a driving standpoint, but Id really like to retain it if I can. If anyone has any knowledge of whether the Hall-effect sensor and gauge can operate on 12volts, theres a replacement option,

or if there is a simple solution that I'm overlooking, any advice, experience or ideas are greatly appreciated.

 

[Feistl]

Hey mate,

All 12HTs here in Australia are 12v, so yeah it’s easy to get a good starter and a 12v tacho sensor. You should be able to use the tacho gauge from a HJ47 if you want to stay genuine Toyota, or any after market gauge should work (you may need a signal converter box).

As for the starter, make sure you run a really high quality 0 gauge wire directly from the battery to the starter using properly crimped fittings. Also run a ground strap directly from the battery to the starter or engine block nearby.

While the 12v system works perfectly fine for us, we don’t really see temps below 0c. A 12v system in like -20c is probably going to struggle.

If you get desperate I can probably do some testing for you... I have a couple of 12HTs and a HJ47 diesel tacho and multiple after market 12v tacho gauges. Only problem is the majority is packed away in boxes somewhere....

 

[wormfood]

Do you have a 24v 40 series tach? I have a 12v one in good condition I'd be willing to trade for a good condition 24v one

 

[KeepCruzin]

Do you have a 24v 40 series tach? I have a 12v one in good condition I'd be willing to trade for a good condition 24v one

I dont have a 24v 40 series tach, but I do have a 24v HJ61 tach for the 12HT (it will have the little red and green turbo indicator lights at the bottom). You could probably make it work in the 40 series housing you have. The gauge and sending unit are the difficult parts for me to find in 12v

 

[KeepCruzin]

Hey mate,

All 12HTs here in Australia are 12v, so yeah it’s easy to get a good starter and a 12v tacho sensor. You should be able to use the tacho gauge from a HJ47 if you want to stay genuine Toyota, or any after market gauge should work (you may need a signal converter box).

As for the starter, make sure you run a really high quality 0 gauge wire directly from the battery to the starter using properly crimped fittings. Also run a ground strap directly from the battery to the starter or engine block nearby.

While the 12v system works perfectly fine for us, we don’t really see temps below 0c. A 12v system in like -20c is probably going to struggle.

If you get desperate I can probably do some testing for you... I have a couple of 12HTs and a HJ47 diesel tacho and multiple after market 12v tacho gauges. Only problem is the majority is packed away in boxes somewhere....

This was very helpful, thank you. Do you have any idea if the 24volt sensor unit that is threaded into the bellhousing can be operated on 12volts? Ive been doing a lot of hunting but cant find a source for a 12volt sending unit/sensor for the bellhousing. Do you think I could use a factory 12volt tachometer from an FJ60? Those arent designed for a Hall-effect sensor though.