92- Tach Drive

[jwbronco]

I'm going to try to solve the problem with driving an aftermarket tachometer with some simple, inexpensive solutions. I'd like to know what other people have tried so far. I'm curious if anyone has a tachometer they'd like to try. I haven't ordered a tachometer yet but I have autometer z series for my boost and pyro.



1. I've ordered some dc-dc converters to bump the voltage up to 12v for the signal.



2. If that dc-dc converter doesn't work I'm going to order some solid state relays that trigger off of 5 volts.







In order to make sure any of the circuits could handle the pulsing I had to break down the frequency of the pulses.



500 rpm = 1000 ppm / 60 = 16. 67hz / 1 = 60ms

3500 rpm = 7000 ppm / 60 = 116. 67hz / 1 = 8. 57ms



those numbers are what I'm looking for switching time on the relays.

 

[RWherley]

I just used a 4000rpm tach from Isspro and wired it to the factory harness under the dash.

 

[HHhuntitall]

I just used a 4000rpm tach from Isspro and wired it to the factory harness under the dash.

What he said... ...

That or you can get an ISSPRO magnet sensor for an ISSPRO Tach, too..... Interestingly, if you look up the R8912-92, it is the tach sending unit wire loom, and the R8912 is the sending unit for the 92-93 Dodge... ...

 

[dodgenstein]

Why not use an alternator output to signal a tach? I have had the local shop add a W (?) output wire to several alternators and used tachs that said "sensor required available seperately".

 

[jwbronco]

I know the ISSPRO R8503 works with the factory wiring by using R8912-92. I'm trying to get Autometer 2697 http://autometer.com/cat_gaugedetail.aspx?gid=3239&sid=12 to work but it only works with 12v signal and that's what I'm trying to do is adapt the factory signal to a useable signal for it.

I don't want to use the W wire, don't want to use the magnet sensor. I have nothing against the ISSPRO but I want my gauges to match because my other ones are Z Series now.

 

[HHhuntitall]

AH. I misread that... . You have the Autometer Z series... . How'd I read over that?!? Well, anyway, I think you can use the factory tach sending unit, switch the autometer to the 4cyl option, and wire the pulse wire (green wire) to the signal from the tach sending unit. You will have to supply voltage to the sending unit, and I believe that's 5v on the Dodge. If wiring it only for the tach, you might could wire it straight 12v, but I'm not sure if it will burn up the sending unit... ...

 

[jwbronco]

After reading another post I've read that MSD and autometer created tach adapters which should do the trick. It seems a lot of cars putting out a 5v signal for the tach. If you look it up LS1 cars are one of them for sure.

http://www.msdignition.com/Products/Accessories/Tach_Adapters/8913_-_Tach_Driver,_DIS_Ignitions.aspx

http://autometer.com/cat_accessoriesdetail.aspx?vid=99