remember about my tach problem ?

well...it worked in..reverse...wtf ? i was backing up today, and it decided to jump up to 1500 rpms.

but, i have no idea why it wont work in drive ? (going forward...lol)

also, my speedo stopped working, so i took out the cluster...and it broke...my speedo cable broke off...and now that does not work...like...the wire inside of the cable...just a couple of inches..but still...its broken...

aslo, when i took out my gauges...the thing that plugs into the top left (on the back of the cluster) that has two prongs was unpluged ? whats that do ? so i pluged it back in...nothing diffrent happend...but my seat belt sensor was also unplugged, i pluged that back in as well...and also...my sensor for my drivers side door does not work ? actually, theres not a lil button there...but the passenger side one does..everynow and then... help ?

 

*bump*

 

what does bump,amLAMFO MEAN

 

it moves my post back up to the top so people that didnt see it before see it...

 

*bump again* i need some help guys...

 

The tach is driven off of the trailing coils primary circuit (trailing coil NEG post). If the Trailing ignitor or coil fails = no tach. Check the trailing ignition for spark. If the wire between your coil terminal and tach guage break, this also = no tach. In your case it actually sounds like a broken or loose wire because when you backed up the tach worked. In reverse the engine gets twisted the opposite way against it's mounts/frame. It's still turning the crank the same direction but it's power is applied the opposite way against the body. This means the wires connected to it are pushed the other direction during this time also. Check the ignitor wiring at the distributor for a loose connection or a loose trailing coil to distrubutor cable (the one that carries the spark). Also check the motor mounts on each front lower corner of the engine to frame for loose or missing nuts allowing too much movement, this causes wiring to be pulled loose.

If all is working and connected you should check to see if the signal is reaching the instrument cluster at its plug connector. I don't know what year or engine you have, or if it matters, but get ahold of a wiring diagram to find which one is the tach signal wire, it's the black one leaving the Trailing coil NEG post. These diagrams are availiable online, check the FAQs page for the links. If the signal is getting to your tach and the tach no worky then throw it out and put in another one.

When my tach quit working ('81 12A) it was because the Trailing coil was defective. The spark was arching/jumping from the tower/cable connector to it's own negative terminal until it burnt up completely. There was obvious damage on the melted down cap.

Good luck,
Vernon