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1979 Trans Am - 403 Electrical Issues?

Boozie02

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Hello all. Long time listener, first time caller. Sorry for the long first post. I'm new to the group, but not new to the f-bodies. I've owned several in my day including a 71 Formula, a 77 T/A, two 79 Fomulas and now I just purchased a 79 Trans Am (403) as a project car. I seem to have always been drawn to these cars for some reason... Anyway, the most recent purchase needed some work before I even attempted to try and start it, but overall, it is in pretty good shape for sitting and pretty complete compared to others I've seen in the same price range. Only a couple small body rust areas, one small area in the trunk and a small area in the floorboard. Definitely still needs some TLC, but has a lot of potential. I’m not looking for it to be a show car. I just wanted something to throw money I don’t have at, fix it up over time and maybe cruise around town in it every now and again. Regardless, I’m having some electrical issues that are baffling me and I’ll start with the "short" version (pun intended), then you can read on if you want to see what I’ve done to try and correct it etc...

I'll start off with the fact that the previous owner had done some wiring under the dash, but nothing out of the ordinary for these cars. Looks like he put a stereo, amp and subwoofer in it. The sub is still there but all amp wiring and everything else aftermarket stereo related was taken out. The factory wires are still there and mostly intact. Most were just tapped into, and a couple were cut but the connectors were still there. I cleaned up everything I could see that was either exposed or cut and put them back together according to the wiring diagram, but it really wasn't much and was pretty obvious where they were supposed to go. I installed a new battery, and one fusible link was replaced as it was burned up when I purchased the car. I assumed it burned from hastily removing the stereo equipment... I visibly checked all the engine bay wiring after finding the blown fusible link. No shorts or exposed wires that I can find. The car starts and runs pretty good after a new carburetor, vacuum hoses and tune up etc... The battery can be left installed for hours, but once the car is started, shut off and the key turned off/removed from the ignition, the battery cables start smoking after a few minutes. Once again, no shorts or exposed wires etc that I can find and no smoking wires before the car is started. Only after it’s shut off. That's the "short" version. Read on if you want the rest of the story...

The first time I tried to start it, all the lights were dim and it was sluggish to crank, but it did start and immediately die. The battery I used was old and tested bad, so I purchased a new one. After installing the new battery, I got nothing from the key or no dash lights. Turned out that the fusible link was fried, so I pulled the starter, replaced the fusible link, put it all back together. Everything came back on as it was supposed to. The battery was connected for a couple hours before I tried starting it to make sure the fusible link didn't burn up again. After waiting, the lights were all bright and it cranked/started right up the first time. I only ran it for less than a minute and turned the key off. I walked away from it for a few minutes, came back in the garage, cleaned up some tools and then out of nowhere I heard a sizzle and saw smoke coming from the starter area. It had to have been at least 5 minutes or more after I shut it off as I had actually videoed that first start. I had time to edit that video a little, send it, along with a few texts to a friend and even got something to drink before it started smoking. I rushed and disconnected the battery. I'm not sure because I was in frenzy mode, but I think it actually stopped sizzling on it's own before I could get the side posts off. Maybe no. I assumed the fusible link had fried again for some reason, so I took the starter back off. To my surprise, neither of the fusible links were burned up. There was a tiny burn spot on the positive battery cable rubber "insulator" on the L-shaped connector that goes to the solenoid. Since it's a tight fit, I thought maybe it had touched the block or heat shield, so before re-installing it, I made the mistake of wrapping it in electrical tape. I re-installed the starter, let it sit for a few minutes, then started the car again. Everything seemed normal and I ran it for about a minute, then turned the key off. I stood there waiting for more smoke etc and unfortunately I got it. This time it was only about 30 seconds before I heard the sizzle & saw smoke, but this time the rubber insulator on the L-connector burst into flames due to the electrical tape I put on it. My bad... At the same time, the negative battery cable also started sizzling and smoking. It was HOT and I could see a hole developing in the insulation as I was trying to remove the cable. I disconnected the battery, then had the alternator and starter tested at O'Reilly Auto (both were good). I've pulled all the starter wires up from the tube and checked for anything exposed and/or shorts. Also checked the alternator wires, the red wire going to the A/C and the red wire going to the fuse block, but I am not finding anything exposed or that would be shorting out. As I'm looking for shorts, it’s becoming apparent that the previous owner must have been having issues and was doing the same. Every wire I go to check, there's evidence that he had been there checking too.

For the next round, I have changed the battery terminals from side post to quick release top post (just in case), I have replaced the battery cable to the starter, replaced the black negative to block cable and cleaned the contact area, disconnected the alternator, disconnected the red A/C wire, replaced the one fusible link that I hadn't yet replaced (just in case), disconnected the headlight switch and even purchased a new starter just in case. The old starter seems to be fine, but I've read that they can pass O'Reilly's starter test, but could still be shorting out. I haven't re-connected the battery since doing all of that. Anybody have a similar issue where it waits a while after the key is turned off before burning it's self up? What kind of testing can I do without burning something up. Is there anything else I could check before trying again and possibly burning the car and my house up tonight? Thanx in advance
 

Knightrider189

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It sounds like you definitely have a hot wire grounding out someplace.
Tracing electrical can be a nightmare.


1989 Pontiac Formula Firebird, 5.7, all OEM
 
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Munkyslut

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Bloody hell, that’s some problem!

Start by eliminating components, whip the starter off & power it up with jumper cables while it’s lying on the garage floor & watch it closely.

It’s possible that the solenoid has failed internal insulation or switching; after operation, it takes a few seconds for the battery connection to be isolated.

It’s worth a check.👍

As you’ve had the alternator checked, you can eliminate that, but check the wiring loom to it carefully & look for corroded connectors & frayed or exposed cables.

Anything like that causes a lot of resistance & that in turn produces heat & even more resistance & then smoke!