Up in smoke

[oldiron]

Well yesterday I pulled my 4x4 out the shop getting ready to go to Jerry Jones get together on Sat. when my truck just stopped running. Then the smoke started to roll out from the dash.
I had no lights no power. I felt under the dash for hot wires and didn't find anything. I checked the master fuse from the battery and it was blown.
I replaced the fuse and checked under the dash again with key off. No smoke or heat.
Then I turned on the key and here comes the smoke again. I have a relay under the dash that connects to a hidden switch that prevents the engine from starting. The relay just started cooking. Turned the key off and pulled the wires going to the engine thinking maybe a wire was shorting out. But when I turned the key on again the relay still got hot. Bad relay. Replaced it.
Now I have no tach, the left turn signal doesn't work and the alternator is charging at 36 volts.
Replaced the alternator and now my tach still doesnt work and the left turn signal works some times. I dont trust the truck enoungh now to travel 900 miles to Jerry's this week.
I'm ready to pull out my hair if I had any left.

[yote1234]

sounds like some shorted wires... just grab some elec, tape and follow each wire..

[oldiron]

I have been working on this for the last 18 hours. Just getting frustrated. Looks like the tach is fried. Just put in a new wiring harness so I have checked all of the connections and followed all of the wire looms checking for cut wires or ones that might have gotten chaffed.
I did have a backup camera installed and the monitor also went up in smoke. I guess it couldn't take the high voltage.

[chevy_mike]

Yeah, most 12 volt items don't take kindly to 36 volts for very long. Tach's are really sensitive to wiring and shorts, connected backwards, over voltage, etc. blows them really quick.

Good luck.

[oldiron]

Well after thrashing on it for the last two days, I think I got all of the bugs worked out of it electrical wise. Now fix the valve cover oil leak that just reared its ugly head.
But then again if it didn't leak oil then it wouldn't be a Chevy.

[Critter]

Sounds like you got it under control, but what do you think caused it? Is it possible that the voltage regulator went out and caused all of this, or did something elsewhere short out and the regulator was collateral damage???

[oldiron]

I think the relay that I was using had an interal short then the alt. tried to keep up with the voltage load and the internal regulator failed and the result was a 36 volt spike that fried the tach and the monitor.
I took the alt. back to where I bought it and they checked it out and sure enough it was putting out over 36 volts. I had the alt. for over a year but they replaced it for free. It is nice to work with a local shop that specializes in alt. and starters and customer service. I just wanted it fixed and I figured that after having it for a year there would be no warranty.