HELP! Tach will not work/ no signal from wire!

[NoDestiny]

OK turbo mini, Stage 5 cal... Just put on a 2.5" swing valve and the exhaust pipe is at my welder, but I had to pull my mini out of the shop for a few other cars while its getting done. As far as I can remember (because surely I would notice it didn't work then) it was working fine. A few days later, I plugged in a solar powered trickle charger (after being in my neon for a week, no problem) to help keep the battery happy. The other day, I went to start it up. After starting up, I noticed the tach wasn't moving. Reved a few times, no tach still.

To determine my tach didn't die, I hooked up my laptop to my zeitronix system (which is tapped into the wire just behind the tach) to see if it sees a signal (which it has every time with no problems)... nothing.

Anybody have an idea on why I have no signal on that wire???

[NoDestiny]

Hate to bump this, but I would like to get this van going and I don't have many ideas!

[IROCNOROLL]

Factory tach?

[NoDestiny]

Quote:

Originally Posted by IROCNOROLL Factory tach?

Yes, but I doubt the tach itself is having issues as my logging system won't see RPMs as well!

[IROCNOROLL]

Quote:

Originally Posted by NoDestiny Yes, but I doubt the tach itself is having issues as my logging system won't see RPMs as well!

Yes... but the T/mini factory tach is driven by a usually troublesome PC board located to the upper right side of the cluster when it's removed from the dash. These boards have issues. Often, simply re-seating the PCB in it's edge connector on the side of the cluster will bring the tach operation back, and then the RPM signal you are using should be restored as well. Also this PCB commonly suffers from cold solder connections, and re-flowing the solder for the component connections on the PCB can bring the board back to active duty.

So... if the tach signal you have been tapping into on the cluster is after this PCB, this may solve the problem. BTW... this is one of the junkyard treasures I usually try to collect when I am in the dash on a parts run. Nice to have a couple to try in the case of an intermittent or dead tach. Any '89 and up car or mini with the factory tach has it. Older units may as well, but I have not been into those dashes to know for sure.

[85lebaront2]

To my knowledge, all factory analog tachs, not just minis, used this tachometer drive board until the advent of the BCM controlled instruments. There are variations in style, but they are used, even in the L bodies. Digital clusters are a whole different breed.

[IROCNOROLL]

I figured as much but like I wrote, not having had my fingers in myself, not sure. If the signal used is a processed drive signal after this PCB, there is a good chance this may be the source of the missing signal.

[NoDestiny]

Great info, any pics by chance?

So will this effect the wire going to the back of the cluster itself (as part of the harness)? Because that is where I have the wire tapped for my logging which stopping reading the same time the tach died.