Tachometer test?

06VMAXIMUS · Jun 21, 2012

Ok, so my daughters boyfriend picked up his 98 max tonight, and we started tinkering with the "issues" that it has. One of them is that the tach is dead. I checked the wires at the back, 2 of them have power ( brown and can't remember the other), and the grey wire is obviously a signal wire which I don't believe can be checked? So I guess that's my question here...can the grey wire be checked somehow? I suppose I could take the tach off of my 06 and swap em, but that's a lot of wrenching! Any ideas?

Rhoy Carter · Jun 21, 2012

check the conecter under the left scoop for corrosion, and you can check the grey wire to make sure it is not broken

06VMAXIMUS · Jun 21, 2012

So the grey wire goes from the tach, to under the left scoop somewhere? I will see if I can track it down tomorrow. Thanks!

gamorg02 · Jun 21, 2012

goto autozone get a generic tac and hook it up, then return it. doesn' tmatter if it doesn't read 'right', even if it measures half or double the rpms you'll know if you're getting signal.

bkuhr · Jun 22, 2012

06VMAXIMUS said:
I checked the wires at the back, 2 of them have power ( brown and can't remember the other), QUOTE]

Not 100% about vmax, and have not seen wiring diagram, but I beleive the 3 wires should be power, ground, signal. If you have power on 2 as stated, then the ground wire IS broken, and is likely your problem.
(power into tach, runs thru tach coil/electronics, and appears on ground terminal with no place to go. If ground terminal was grounded, and volts to ground was tested, the ground terminal would indicate 0, as well as the signal terminal)