Melted plastic in power distribution box.

[RCAR50]

So I was rewiring my cd player and amp power lead, done by the previous owner because anytime the rpms dropped below 700 or so or I turned on the a/c or sometimes even hit the brakes lights the radio would die and come back on.....

I had thought this was due to a bad alternator or something similar but then read that bad grounds could also be the cause so I decided to pull the dash apart and fix it.

At the same time I was going to reinstall the amp lead at the battery and while looking for a clean route I noticed this under the relay cover...

 

Anyway, what do ya'll think? What could have caused it and what issues could it cause??

 

Thanks in advance...

Edited September 20, 2015 by RCAR50

[01Pathmaker]

Ewww, that'd be caused by excessive heat, could be from a loose or dirty connection or excessive voltage. Had you ever peaked in there before today? Could have been something that happened prior to your ownership? I've seen some wacky stuff happen when John Q. Public thinks he knows how to wire stuff up, up to and including the whole thing burning to the ground. I once purchased a used truck that had 5 8" Dick Cepek 100 watt lights on a nice rack. Came find a few weeks after purchase, when some of the electronics started acting hinky, the fuse box was melting a bit every time the lights were turned on! The brainiac that did the install had wrapped a 16ga wire around the hot side of the cigarette lighter fuse and run that up to the 2 switches to power 500 was worth of lighting! No fuses, no relays, improper wire choice! I was disgusted and very surprised the thing hadn't burned up! Ever since then, I always look at all the fuse boxes and relay centers on any used vehicle I consider buying, if anything looks shoddy, move on to the next one.

 

Wow, sorry that kind of turned into a rant...

[RCAR50]

Not a rant, it's fine...

 

I would imagine it has been that way since I purchased the truck, but I've been in there before and didn't notice it.

 

It wouldn't start when I first bought it so I know I've been all through it trying to track down the issue, ended up being just a loose batt terminal (though it looked and felt just fine).

I suppose it could have happened somewhere between me first looking in there to replacing the starter then finally replacing the terminals for the hell of it.

 

I'll have to head to the wrecking yard and disassemble one and get the pieces I need.

 

Nothing seems to not work properly except for the radio for a breif second at very low RPMS or occasionally with added draw like turning on a/c or lights. I just figured that the battery was getting old...the radio just blinks on and off with the ignition in "acc" position but everything else works and headlights do not seem extraordinarily dim...

 

Does anyoneknow what that block is responsible for? It just says battery main on the cover for that section. Probably power distribution? Sounds like it could be the cause of my little issue to me...

Edited September 21, 2015 by RCAR50

[Precise1]

I'll go out and look this evening when it isn't 100 degrees, but I'd guess that you have had a short somewhere or have way too much unfused draw. The amp draw to melt plastic like that is probably starter related, but something is definitely wrong!

 

Ewww, that'd be caused by excessive heat, could be from a loose or dirty connection or excessive voltage. Had you ever peaked in there before today? Could have been something that happened prior to your ownership? I've seen some wacky stuff happen when John Q. Public thinks he knows how to wire stuff up, up to and including the whole thing burning to the ground. I once purchased a used truck that had 5 8" Dick Cepek 100 watt lights on a nice rack. Came find a few weeks after purchase, when some of the electronics started acting hinky, the fuse box was melting a bit every time the lights were turned on! The brainiac that did the install had wrapped a 16ga wire around the hot side of the cigarette lighter fuse and run that up to the 2 switches to power 500 was worth of lighting! No fuses, no relays, improper wire choice! I was disgusted and very surprised the thing hadn't burned up! Ever since then, I always look at all the fuse boxes and relay centers on any used vehicle I consider buying, if anything looks shoddy, move on to the next one.

Wow, sorry that kind of turned into a rant...

I damn near sprayed my monitor with beer when I read that!

40+ amps through unfused 16 gauge wire? That whole run was a fusible link!

Mind bogglingly stupid aside, the power loss probably meant those lights were only putting out 75% of rated lumens anyway...

 

I'm currently toying around with a simple/small photo-voltaic battery backup system, and while the charge from the panels is minor, the power from the 2 12 volt, deep cycle, 90 amp/hr batteries linked in parallel is nothing to play with. Everything there is 2 gauge wire, shielded and protected terminals, etc. I can pull as much as 150+ amps peak (normally won't do 10% of that), but wiring is something to overkill, not just throw together!

 

B

[RCAR50]

Thanks. It must have been when I was changing the starter and cranking it for long periods of time.

All I've added was an additional 12 volt socket behind the dash face to wire in my cell charger and GPS power wire, piggy backed into the stock power socket so it just pops a simple fuse if it was too much...months in use and never has yet so it's obviously handling it just fine.