Complete shut down of electrical system! (Page 2/3)
olejoedad FEB 03, 08:09 AM
If you have no power at all, the problem would be that

1. Both links to the chassis harness from the BJT are blown. (A and B in the picture above)

2. The wire feeding power from the battery to the BJT is bad.

3. The BJT is corroded.

I suspect number 2

A note - the C500 is waterproof, unless someone has cleaned all of the waterproofing paste from it.
Regardless, no circuits that pass them the the C500 would cause your problem.
Kitskaboodle FEB 03, 01:22 PM
Question:
Fusible link wires A & B. They both go to the upper stud on the terminal block. Can I assume there is break / connection going the other way not much further downstream from the black splice thingie? I also assume I will need to graft in a section of new fusible wire. I heard that the length of wire should not exceed 9 inches.
Thanks, Kit

[This message has been edited by Kitskaboodle (edited 02-03-2021).]

olejoedad FEB 03, 07:33 PM
Do you have power at the BJT?
Kitskaboodle FEB 03, 10:12 PM
BJT?
You are referring to the junction box block?
As an FYI my car is at work in the parking lot and I have not been able to get to it.
Kit
olejoedad FEB 03, 10:47 PM
BJT - battery junction terminal

It is located below the C500.

That's the proper name for the terminal box we are discussing.

The two posts on the BJT are connected by a strap with two holes. This strap is at the end of the heavy cable from the alternator charge post.
There is also a cable from the battery positive terminal.

When you get to your car, you need to use your test meter to determine if there is any power at the BJT.

It should have the same voltage as your battery.
skywurz FEB 03, 10:57 PM
Im still anxiously awaiting the solution. Im still betting on loose corroded terminal of some sort. I really really doubt you blew a fusible link. Always keep Occam's Razor, in mind “the simplest solution is almost always the best.” goes the other way for troubleshooting. Don't overlook the small easy simple stuff.
cvxjet FEB 03, 11:00 PM
Ok....You need to do a couple of tests to see what is going on;

1) Test for power at the junction block (See picture)

2) If you have power there, then use a small needle and push it thru the wires at the spots indicated one at a time and see if you have power on teh other side of the Fusible link.
Kitskaboodle FEB 04, 05:41 PM
Ok guys...I was able to get outside to check a few things:
I checked the JBT studs first - NO POWER
Took out the spare in the front and checked actual battery voltage at the battery terminals- 7.78 volts!

Yes, 7.78 is way to low but it would cause there to be nothing at the ignition key and nothing at the junction box posts??

Two fyi’s.....
I verified the battery Ground cable connection to the frame rail. (It’s fine)
When I turn the ignition key, I notice a tiny bit of needle movement at the aux gauge pkg. I upgraded my 85 to the aux gauge pkg.
Thanks, Kit

[This message has been edited by Kitskaboodle (edited 02-04-2021).]

Mike in Sydney FEB 04, 06:44 PM

quote
Originally posted by Kitskaboodle:

Took out the spare in the front and checked actual battery voltage at the battery terminals- 7.78 volts!

Yes, 7.78 is way to low but it would cause there to be nothing at the ignition key and nothing at the junction box posts??




Sounds like you've checked all the wiring / connections so I'm guessing it's a bad battery, bad alternator, or a severely discharged battery. I recently tried to start one of my GT's after it had set for a while (body panels removed for sanding and painting). Got nothing when I turned the key. No clicks from the starter solenoid, no courtesy lights and no chimes from the blue thingy-dingy. Checking the battery voltage at the terminals gave me a little over 8-volts. When I connected my digital battery charger, it would not register as being connected and gave me error codes. I took the battery out and connected it to my old Craftsman 10-amp battery charger (I have to run it through a stepdown transformer, here). It pegged the needle but the battery began to take a charge. When the voltage got to 11 volts, I switched to a deep charge cycle. 24-hours later it was holding at 12.6-volts.

You may be lucky like I was but I suggest you pull the battery and have it tested. You could have a couple of shorted cells. By the way, did you try to jump start the car? If so, did it start? Can you get it to someplace where they can test the battery and the alternator?

Good luck. I don't envy you. Electrical gremlins are the hardest to find.
Kitskaboodle FEB 05, 04:26 PM
Ok, so I went to Wallymart and got a battery.
She started right up no problem. 😆
I have a theory that two plates in the battery somehow shorted together which brought it down to 7.78 volts. Maybe a combination of cheap battery construction and maybe also that my car is lowered and tends to ride a little hard and maybe shaking the innards of the battery?

Anyways, big lesson learned is never to assume and that even if your battery in your Fiero reads 8 volts, it is (in my case) not enough volts to register anything when you turn the key. And I mean NOTHING.
Thanks to all of you for your patience with me and all of your help!
Kit