blowing Fusible link, Cant get truck started!!

[tatkins85]

im going to copy and paste a couple things on information i have started on another thread. Im running out of time to fix this and im not getting much help because there are so many things that can be wrong.

My truck got started yesterday and a puff of smoke came from the steering column, instantly turned the truck off. Now the truck wont start at all.
Truck has power to door locks, cargo light, power windows when the key is turned to a run position, all surrounding lights, hazards, ac blower, blinkers, and the light on top of the ignition switch is on.
The truck does NOT have power to any of the gauges, stereo, turn key buzzing noise, all of the dash lights, and truck wont run.
I ran a wire to the FSS and jumped the starter to get it running so i could get it home from the tranny shop. I attempted to replace the ignition switch but autozone gave me the wrong one, so i went back and had to look at the screen with the guy and the only one that looked similar was from a 1994. so i got that one and installed it but still got nothing. I checked all wires under the dash, everything looks good, checked all the fuses, and they were all good except for the int cab lights was blown "so i replaced it". checked for loose wires, reinstalled the ignition switch like 10 times. found blown fusible link so i replaced it with a 40 a fuse. truck worked for about 5 seconds then fuse blew again

right before this happened i lost o/d, thats why i took it to the trans shop could there be a related issue? the guy refused to touch it till i had it working again.

i have checked everything i touched over the last 2 months for loose connections, took out almost every fuse in the fuse box disconnected the heater grid and fuel pump, completely uninstalled the stereo "the guy who installed it before me had wires everywhere", taped up every loose or unconnected end. turned key on and still blowing that fuse link "that i have replaced with a 40a fuse for easy repair".

The trans guy did re wire the entire tranny. but i have driven the truck over 250 miles sense then, and am just now having this problem.

the trans guy said he had smoke out of the steering column. so i dont know for sure if there was or not. i have seen smoke come from the engine department above the fusible links but not inside the cab yet "like he stated"

[collegekid]

If you got a puff of smoke out of the steering column, Im going to bet you burned up a wire in the column, pull your column apart and check every wire that runs to it. Wiring on these things is frustrating, if you want, you can always install a push button starter and bypass the ignition switch

[Tacoclaw]

When I swapped my auto for a stick, I accidentally left my wires between my 4x4 shifter and the case. 2nd time I shifter into 4-wheel drive, I got a stream of smoke from the entire front of the truck and the column.

In my wiring harness, 1990 W250, there's a blue wire that comes out of the keyswitch and distributes power to all underhood items. This also feeds power to the transmission stuff. They all splice together about 1/2 way across the firewall, in one big crimp.

I'm betting you've got a short that rubbed through down on your transmission stuff, although it could technically be any underhood hot. AC, voltage regulator, FSS, Fuel heater, or any others.

Quick way to check the trans is to just unplug it's connector up near the firewall. I rethought this, and it may not work due to the park safety switch. If it blows from just going to key-on, it should work. If you need to crank/start it to test it won't.

Another note: That blue wire distributes to a whole group of wires that are exactly the same color blue. The blue wires you see at your AC clutch connector and voltage regulator are all from there. I didn't notice whether or not the wire at the FSS is blue, since I don't have a FSS and have the wire tied up somewhere.

[oldestof11]

See, I told ya.

[tatkins85]

so i still cant find anything. so i turned my electrical tested on to beep at me when it touches it self, put one end on ground and started touching wires and i got the 16 gauge pink wire with a black stripe coming into the ignition switch to beep at me. its also a power wire. so that wire has power and yet is beeping when i touch ground, so that wire is grounding out somewhere? dont know if that makes any sense, what do you guys think? anyone know what that wire controls?

[tatkins85]

If you got a puff of smoke out of the steering column, Im going to bet you burned up a wire in the column, pull your column apart and check every wire that runs to it. Wiring on these things is frustrating, if you want, you can always install a push button starter and bypass the ignition switch

already inspected every wire very thoroughly and they all check out perfectly

[Tacoclaw]

If it's power out of the switch, then that doesn't really mean anything. It will eventually get to ground through all the things it sends power to. I've spent a couple of hours chasing a "short" I thought I found over the same thing.

Also, what year truck are we talking about here? I'm not familiar with the one controlled with the ECM... Their wires will probably be somewhat different since their OD, charging, and AC are controlled by the computer.

I would still highly suspect those wires key-on wires under your hood...

[tatkins85]

got it working after unplugging this harness. anyone know what this harness is? tans? fuel pump?

[Tacoclaw]

got it working after unplugging this harness. anyone know what this harness is? tans? fuel pump?

Quick way to check the trans is to just unplug it's connector up near the firewall. I rethought this, and it may not work due to the park safety switch. If it blows from just going to key-on, it should work. If you need to crank/start it to test it won't.

That's your guy.

You've got a short to ground on your trans wiring. That sends hot to your 4x4 sensor, park safety sensor, speedo, and whatever else is down there. Check every inch of that big blue wire as it goes down there, then start checking any wires that splice off of it\.

[dazedandconfused]

It's easy for wires to rub down there.

[tatkins85]

WOW. I LOVE YOU GUYS! lol this forum is the best. was just told about it last night. THANK YOU GUYS VERY MUCH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Tacoclaw]

Glad to hear you got it figured out.

[tatkins85]

ok so i tracked it down to this connection on the trans. pulled back the tape and it looked like the wired were pulled out a bit and were touching each other. pulled it out and pulled the wires apart and everything is good. but when i put it back into the top of the trans it blows the fuse again. could the sensor be bad or does that sensor send out a connection to another part of the trans, so my search needs to continue?

[Tacoclaw]

You've officially surpassed my experiences now, I'm a standard trans man.

I'm sure someone here with an auto can tell you what that connector goes to.

[dazedandconfused]

I believe that is the neutral safety switch. I'd folloe the rest of the wiring to be safe but I suppose the swich could be shorted. Which trans do you have 518 or 727? 4x4 or 4x2?