I bought my truck a year ago with a blown engine, and threw a spare in for the time being. When I put in the spare, there was a huge charging issue, where it had been at 17+ volts. It ended up frying my tach and fuel gauge. I have since put a good engine (170 in all 4) and my tach still does not work. I assume the tach runs through the coil to the distributor, or vice versa. I used all parts off good enigne, including coil. Where else could it be at? I hope not behind the dash. Any ideas would be helpful.

 

Ive asked this question at least 6 times on this site. No one seems to know. I get like 60 views, but no replies. I have asked my local mechanics, and they tell me things like a fuse, or bad ground. Well I know its none of these. Can a toyota guru please help me out here!!

 

I am by no means a guru... but had a couple ideas.

Check to make sure you are getting a tach signal by tying into the IG port on the diagnostics plug. If so, maybe you can just wire a new tach of that pin.

I know the factory gauge tach is very sensitive, and if you ran the wrong signal to it... then it's probably fired. If you pull the gauge itself out of the dash you may be able to see what has been damaged, but most likely the problem won't be visible.

If you want to retain the factory gauge, you might try some local salvage yards and just swap your tach out. Of course, you need to be sure the signal is reaching the gauge and is the correct signal for the gauge. Not to much juice.

 

I should have also mentioned that my fuel gauge went out at time of over charging. Also since then, my charge light stays on all the time. But it shows im charging at 12 volts. It has never left me straned or shown any signs of not getting enuff juice? So why is my charge light on? Also does an 81 have a diagnostics plug? Where is this said plug? Under my hood? By coil? Thanks.