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Big rock dennis
New User
Mar 8, 2016, 10:59 AM
Post #1 of 6
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Electrical issiues
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My car is a 1967 Pontiac firebird 400 w/ turbo400 I've owned this car for over twenty years. I will explain as best I can. For some time now I've have had in dash factory gauge problems. I.e. Some times they work fine other times they don't work at all. And sometimes they appear to be stuck on a random number. And when my head lights are on no matter how they were acting prior to turning on head lights they all bury to high or low readings.
When I say all there are four. Temp. Fuel. Oil pressure. Battery. The battery never seems to be affected as the other three. And the blinker lights are lit up as well. It's always bugged me but never could figure it out. I've went thur all the grounds at the battery. Battery to engine block. Engine block to car body. Now the current problem which may or may not be related I think probably is. While driving the last month or so at night I turn on the high beams but after having them on for say 20 min or so the just go out I hit dimmer switch go to low beams they work fine back to high beams within a few seconds out again. So two days ago this happened when I got to my destination. I shut the car off turned off the head lights but the dash light stayed on I couldn't get them to turn off. I pulled every fuse, still on. So I unhooked the negative battery cable and noticed that the post connector had actually started to melt the lead it's made of. Upon further looking a wire from the coils negitive post that runs to a firewall plug directly behind the fuse box had burnt the majority of the insulation off. The factory wire has a kind of like cloth insulator covering the wire. The car turns over fine. But no spark from the coil. Now the stock distributor had a HEI convertion kit installed along time ago so I run a MSD blaster 2 coil. What I've done trying to fix this is bought new coil. Cleaned all battery connections. Inspect all wiring to and from starter. Found a few places where there was exposed wire, cracked insulator cover. Just started replacing those wires. that's where I'm at now. I just struggle with electrical issues. If you need pictures I can send some. Thanks in advance.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 8, 2016, 12:10 PM
Post #2 of 6
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Re: Electrical issiues
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Quote">>Found a few places where there was exposed wire, cracked insulator cover. Just started replacing those wires. that's where I'm at now.Just started replacing those wires. that's where I'm at now.<<"
Until that's 100% taken care of if it takes new wire all the way not much I can say where to go next.
Melted at battery cable is a pretty dang hard bat+ short! Other issues would come from that alone,
T
(This post was edited by Tom Greenleaf on Mar 8, 2016, 12:14 PM)
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Big rock dennis
New User
Mar 8, 2016, 1:34 PM
Post #3 of 6
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Re: Electrical issiues
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Tom when you say hard electrical short. I understand what you mean. But where does your gut tell you to look first. I'm starting at the battery and working towards the starter. Just because that's the largest gauge wire thinking it would short harder than anywhere else. And would this be a positive grounding out or a negitive in contact with a positive to be able to melt battery connector? Or could it be either of them do that?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 8, 2016, 2:18 PM
Post #4 of 6
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Re: Electrical issiues
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Terminology: It's melting connectors so POSITIVE something of large gauge (battery cable is first to mind) is capable of a direct connection with ground. Ground on this car is sub frames - both, body metal and first is engine block.
Not sure what changes in metals used for wire or connections? Could be changed from OE which would be lead at battery which melts at a low temp and eyelet ends of cables/wire at least a coated steel if not copper?
Copper doesn't melt with any power the 12V system has so that isn't melting but insulation of it can. What bared the wires? Exhaust manifold or pipe too close or just brittle with age and no longer fastened in place to stay away from those things.
I suppose a dead short in the starter or solenoid somehow drawing current a lot but not enough to engage starter in question?
The other parts mentioned were possibly just too close to something else that was hot. Smaller gauge wire will heat faster if shorted and melt insulation and plug end plastics.
Your job is and has to be what can be that much of a hard short - my words for about taking jumper cables and purposely putting them from battery positive terminal to battery negative cable would create some real show!
Find what can be that harsh. You are there seeing bared wire with insulation exposed so that's got to be fixed then anything it harmed if that exact area was the short or weak for the insulation.
Umm? Battery plastic may also have taken a destructing hit if hot there. Not sure patching that is going to work out if so?
T
(edit more in)
Note that all instructions for disconnecting a batter will say disconnect NEGATIVE first then POSITIVE AND REVERSE THAT TO HOOK IT BACK UP. Reason. The metal tools used to disconnect positive if first if wrench or whatever hit body or engine metal it would short but not if negative was already disconnected. Just a point that this is a positive short to negative whatever........
(This post was edited by Tom Greenleaf on Mar 8, 2016, 2:22 PM)
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Big rock dennis
New User
Mar 8, 2016, 3:15 PM
Post #5 of 6
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Re: Electrical issiues
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Thank for the tips I'll go after it later today and get back to you. Thanks again
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Mar 8, 2016, 3:42 PM
Post #6 of 6
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Re: Electrical issiues
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Good luck. Do make sure if replacing wire you do get the right type and gauge wire. You may have to make your own ends/connections. Point is wire is not just wire you want automotive grade which is totally different from other uses.
Once they are all in place then you can find out what else is still needed,
T
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