84 FJ60 Intermittent tach function??? Tried everything I know??? (1 Viewer)

[andyg2333]

All of the sudden one day the tach. quit working on my 84 fj60. The white and red wire coming from the distributor the wire covering was burnt looking and wire insulation was very questionable at best, cut out stock green plug and checked signal then used marine grade butt connectors, so that is solved. After this still an intermittent tach. worked sometimes, didnt sometimes, no matter what I did jiggle wires, test voltage, it either worked or didnt with no hints of an obvious problem, cleaned all associated connections. Everything around the coil and ignitor look clean and tight no rubbing burning. So next I unhooked the green plug with tach signal from the harness, blade terminal on stock plug for tach signal with jumper wire to ring terminal on neg. side of coil ( with stock wire from neg coil to igniter still attached). Boom, tach working, unhooked it tach quit working, did this a few time to test, working well. About 2 hours later I go to drive the truck, tach not working, fiddled with it to no avail. Next day started it up after hooking stock tach signal plugs back up and removing jumper wire, tach is working, change back and forth from jump to stock connection tach continues to work, I leave it stock. The next time I drive it no tach agian. I would think maybe volt. regulator but no other elect. problems at all. Could it be the emissions computer? If i do the green wire mod I can remove the computer correct? I simply dont think it is the tach itself or the connection to it. Can I remove the guage cluster without removing the whole dash? Ive diagnosed and check everything on the wire diagram except the actual tach. Truck has been babied and has 165,000 miles, it sat alot more of its life than it was on the road. All wiring and every thing else on this truck is stock and CLEAN. Any help would be greatly appreciated. Thanks
Andy

 

[andyg2333]

If the red and white wires from the dist. to the igniter werent connected properly would the vehicle run? The only way the vehicle wont run is if i disconnect the neg wire from the coil to the igniter.

 

[andyg2333]

Everytime I turn the ignition to on, the tach jumps really quick while other lights on the dash come on, it does this everytime whether the tach works after starting or not. Every other older land cruiser Ive owned or worked on ( a lot) does the same this leads me to beleive when the key is on its getting what it needs (voltage) then something interferes, this also rules out a sticky mechanism or some other mechanical aspect as far as the tach itself goes. Which screws need to be removed for the gauge panel, there are two obvious ones on the top corners, looks like one in the top "tunnel" of the speedo and multi gauge, is this it? I have a $10 tach from ebay on the way, this will help me confirm or deny the gauge itself. Could the emissions computer have something to do with it? If new tach wont work after installed in engine bay it has to be the igniter, right ?

 

[andyg2333]

Thanks very much for your input, it is greatly appreciated. I have personally experienced the igniter being the cause of tach failure on 1st gen hilux's, not the same exact wiring or situation but very similar. I also have never experienced this with a landcruiser. I will hook up new tach under the hood, and over time this should confirm or eliminate the tach itself. Right now the tach. is working again, been chasing this problem for better part of a month.