melted black/white dash wire need help

[expo5.0]

dash started smoking today and everything shut down on the truck. took dash apart and investigated to find a black and white 16 gauge or so wire melted. ripped into it further and found that wire was 1 of 8 wires that appear to be the same and connect to two larger gauge bl/wh wires in the middle of the dash. (all of thse wire were located in the main wire pack running through the top of the dash- they appear to go on to the ecu)

also, found that my factory ground strap on the back of the motor was melted/cut. these problems definitely seem to be related.

anybody have a good diagram of where that grounding strap actually mounts to my 5.0? i can't see it from the top and until i fix this my truck is stuck all the way down (exhaust on the ground).


my hypothesis is that the ground wire got messed up and shorted out the other wire leading ot massive failure. i need a guiding hand in how to proceed from here and get the truck running again. can't leave it where it is for now.

 

[budwich]

The BK/W appears to power things like door locks, power seat options if you have them along with headlamp relay among other things. There are two "feeds" coming from the power distribution box... both on 30 amp fuse links so they are expecting to see a bit of current... at least on the main feeds. As you indicate, one feed appears to splice to a large number of things (doors / seat stuff) while the other only runs to a couple. This is on the power side of things.

On the 5.0, BK/W is used on the ground side of things to provide grounds for stuff like instrument cluster, power train control module, and a lot of other stuff... at least that's my read on the schematic that I got.

Probably doesn't help much as you certainly need to have a schematic in hand to flow something as significant as this.

 

[big_hoovie]

If you have a haynes manual available, there are electrical shematics in the back of the book.

gl with your X

 

[BauerOnDubs]

black w/ white is a ground wire... I'd start by replacing ALL ground wires in the dash, and finding out what blew, and more importantly, why?

This is all it gave me for the ground strap...

Hope this helps. I highly recommend alldatadiy.com over haynes manuals. You can print-out what you need, get it dirty working, and throw it away. The "book" never gets dirty.

 

[expo5.0]

ok, so it appears to be a coincidence that there are 8 wires there and i have 8 cylinders... that was my first thought.

i will start by fixing the under the hood grounding strap (although i still don't see how the heck i'm gonna reach wherever it connects to)

I'm pretty sure the problem started there (i think i noticed it was slightly frayed a few months ago) and then spread to the wire- so im hoping that by fixing that i will alleviate teh condition that was causing that wire to melt. then once that is done i should be able to troubleshoot the other wire by investigating what is not still not working.

would the engine ground strap being off be enough to shut the car down completely? ie- no power to anything or did i likely cause some other damage/fuse blowing at the same time.

 

[Jbrobeck]

The ground strap from the engine to the body is a pretty major link, though I think you should still see SOME power in your truck even if at a lower voltage. I would go ahead and repair the ground there first and see what you get power to, if nothing start fuse hunting. I am not sure how the X works, but most vehicles use a "fusable Link" on the main power wires in case of a major meltown, however these might be the "Mega Fuses" main job in the X, start there to see if you are getting power to the distribution boxes.

Josh

 

[expo5.0]

yeah, sounds good.

i'll defnitely start by regounding that and i know where to look if that doesn't at least start to solve the problem (power distribution under the hood etc.) and hopefully things will start to fall into place, its awful hard to troubleshoot with no power to anything.

 

[expo5.0]

ok i got it running by connecting the ground strap.

now the brakes don't work real well (really not at all)

also, i have yet to fix the burned wire (but it didn't burn any more after i hooked it back up) but other than the brakes sucking i don't know what the problem is?

 

[410Fortune]

Holy crap.

Black/w is always ground.

You have a dead short somewhere, audio install issues?


I cannot figure out why it would effect the braking, as the brakes are vacuum boosted/hydraulic. Only the ABS would be effected by electrical.

 

[expo5.0]

i have no abs anyways.

strangely enough in a vehicle with this much a/v it all worked the whole time/didn't seem to be related to the issue at all.

i'm pretty sure the problem must be from it sitting. any ideas as to how to alleviate it rapidly?

 

[rookieshooter]

i have no abs anyways.

strangely enough in a vehicle with this much a/v it all worked the whole time/didn't seem to be related to the issue at all.

i'm pretty sure the problem must be from it sitting. any ideas as to how to alleviate it rapidly?

Just curious how long was it sitting?

 

[410Fortune]

OKay just a guess from reading this post.
For some reason the demand on your under dash ground feeds was increased a great deal. Things like your starter get thier - feed from the engine block/drivetrain. This is the reason one of the ground cables from the battery goes to the engine block.
the metal straps that connect the body to the frame, hood to body, etc are all there for a reason.

If you have a problem with one or more of your ground cables then it will try to find an alternate source for the ground, in your case the cables under the dash for whatever reason.

We all know what happens when too much power is sent through a wire that is too small, failure, melting of the insulation, etc (heat)

The only other thing that will cause smoking/melting is a dead short (ground wire insulation is breeched by a + wire, + wire makes contact with chasis ground, etc)

I would start by checking all your main battery ground cables.
With the amount of audio stuff I imagin your are running the stock cables may just be way too undersized to handle the ground load being placed on the transfer from frame/chasis to battery(ies)
Now you can never have too many ground straps, from the battery - terminals to the body at the inner fender, rad core, and firewall. BIG cable from battery - to frame. Cable from frame to engine/trans. and cables from frame to body might all be a good idea, replace the factory woven straps with clip on connectors to actual stranded wire with ring terminal ends and bolts/self tapping screws to the body.

Good luck! You are lucky it didnt burn down
When I replaced my 4.0L engine one time I forgot to hook up the _ from frame to engine block and the truck wouldnt start (weak starter) couldnt figure it out for a day or two, but then I noticed the capilary tube for my coolant temp gage was smoking hot to the touch! Turns out my starter was trying to get its ground through this tube, because without the frame to engine strap this was the only metal connecting the chasis to the engine (my case = dash to gage pod, through metal gage body, through capilary tube, to engine block) crazy eh?

Almost burned her down that day...