ratherberacin

hey guys couple questions. just going to put my new isspro tach i got from DNR

from previous posts here i know i have a tach plug in under the dash and the wires are as follows.
black -12v gauge lights
orange 12v common
red-switched 12v
grey w/blue tracer- tach signal

on my isspro r8503 there are three wires are coming out (other than the light harness)

white
red
black

they say on their universal crappy instructions.

white to one of the sensor wires

black wire to the other sensor wire (ground as close as possible to the tachometer head( not sure what the "other sensor" wire means

red wire to 12 keyed power.


so before i melt anything let me see if i have it figured out.
white tach wire to grey/blue tracer tach signal wire
black tach wire to ground
red tach wire to red 12v wire.

sound correct?

deanhinsley1963

sounds right to me.

thrashingcows

Is this the Isspro set-up with the magnets on the balancer? If so I did mine not long ago. The magnetic pick-up had 2 wires, one wire went to common ground, gauge and the sensor, and the other went to the white off the gauge. The rest was as you stated.

ClassA4x4

You're connections is right, BUT if you're not using the ISSPRO harness that they sell your setup won't work. Go to your nearest Radio Shack and buy a $1.79 0.0047 microfarad capacitor and insert it between the sensor wires. You'll be amazed how magically it works.

Billut

So, you'd put the capacitor between white tach wire and grey/blue tracer tach signal wire, that's it ?

DNRCustoms

Well, I will try this. Beacause on a few trucks even with the Isspro harness the tachs have been giving headaches. Called isspro several times and they were little help.

Richie O

Have you talked to Don Wendlick at Isspro? He has helped me before and actually called me to check up on it. Some styles need the capacitor and others do not.

ClassA4x4

Yes. I hope you got it working already.

ClassA4x4

Yes, i've talked with Don but from him what you have to do is their "trade secret"; they sell the harness. so I took it upon myself to research tach circuits that led me to the capacitor solution.

1992gen1_fan

Dug up an oldie, needing to make a harness for a r8503 tach.

Would prety much any 0.0047 capacitor work? or does it need to be uf or pf ect..? I looked on radio shacks website and could only find the little disk type capacitors. I don't know electronic stuff

ClassA4x4

Yes, I'm using the Radio Shack .0047 microfarad disc capacitor, but any .0047 uF (not pF) would work.

1992gen1_fan

Ok thanks for the info. I stopped at a local electronic repair business and closest thing he had was a .005M 1KV capacitor. Was only 50 cents so I bought one just in case. Would that be close enough?

ClassA4x4

Close enough

1992gen1_fan

Cool, thanks

56speedy

1992gen,
Did that work for you and does your tach work now.