1986 Radio - No Power

[Kenobi77]

As title stated. I am getting no power to the fuse and cannot narrow down where to start. Everything is hooked up correctly. Has anyone had a similar problem or have advice on what to check? Everything else is functioning as it should.

 

[franklin2]

The fuse in the fuse box is dead on both sides? With the key in run? You should have two power sources to the radio in 86. One is hot all the time for the radio memory, and the other is only hot with the key in run.

If it is dead on both sides with the key in run, lightly wiggle the keyswitch back and forth and see if it tries to come on.

 

[Kenobi77]

The fuse in the fuse box is dead on both sides? With the key in run? You should have two power sources to the radio in 86. One is hot all the time for the radio memory, and the other is only hot with the key in run.

If it is dead on both sides with the key in run, lightly wiggle the keyswitch back and forth and see if it tries to come on.

Yes, with the key in run. Both sides are dead and wiggling the switch hasn’t done anything.

When I test the terminals, I am getting a reading from both sides. The left is stronger than the right as I hold, but the right is more consistent than the left. As I switch between them, the readings fluctuate until both eventually go dead.

 

[RobbieD]

Do your wipers work?

If so, you likely have an open circuit (i.e. lack of connection) in the fuse box for fuse 11. Wipers and radio share the same on/acc power circuit from the ignition switch, but each has its own fuse in the fuse box.

If the wipers don't work, check for +12 volt on the Black/Lt Green wire at the ignition switch, in switch position "Run" and "ACC". No power there, the problem is in the ignition switch or its connector. if you do have power on Black/Lt Green, trace and test that wire from the ignition switch to the fuse box, looking for the open circuit which is preventing fuse 11 from being powered.

 

[Kenobi77]

Do your wipers work?

If so, you likely have an open circuit (i.e. lack of connection) in the fuse box for fuse 11. Wipers and radio share the same on/acc power circuit from the ignition switch, but each has its own fuse in the fuse box.

If the wipers don't work, check for +12 volt on the Black/Lt Green wire at the ignition switch, in switch position "Run" and "ACC". No power there, the problem is in the ignition switch or its connector. if you do have power on Black/Lt Green, trace and test that wire from the ignition switch to the fuse box, looking for the open circuit which is preventing fuse 11 from being powered.

THANK YOU. Will do that with daylight tomorrow.

 

[Kenobi77]

@RobbieD Have not had time to test the wire yet, but I realized I neglected to address your question about the wipers.

They did not work at all initially (excepting the fluid sprayers) but I tracked that down to a loose ground and harness connection for the motor. Now they work, only on high, and do not activate while the fluid is sprayed.

Hoping I can get the multimeter out tomorrow.

 

[RobbieD]

If the wipers do work (even partially) that suggests the Black/Lt Green Run/Acc wire from the ignition switch is OK, and the problem is likely in the fuse box.

You'll probably have to dismount the fuse box to get a good look at the back (I think it's just two screws, and you'll want to disconnect the battery while you're moving it around).

The Run/Acc wire from the switch will be bussed on the hot side of the fuses. Something I've seen before, is people using foil to "fix" a blowing fuse; seems more common with the radio circuit. When this is done there's no fuse to blow, so connections get too hot and get damaged. If they don't burn to a crisp, they may even still pass current, but fail later.

Anyway, you'll want to look signs of overheating on the backside, where the bus bar is and especially on the terminal and wire on the cold side of the fuse.

1986 schematic is attached; good luck!

 

[Kenobi77]

@RobbieD Looked over the fuse box multiple times and everything was good. I eventually pulled the radio out of the dash and discovered its own fuse was blown. I, obviously have replaced it, but is there anything in the else you recommend I check over before I reinstall the radio? Just want to make sure there isn’t a bigger issue going on.

 

[RobbieD]

@RobbieD Looked over the fuse box multiple times and everything was good. I eventually pulled the radio out of the dash and discovered its own fuse was blown. I, obviously have replaced it, but is there anything in the else you recommend I check over before I reinstall the radio? Just want to make sure there isn’t a bigger issue going on.

Sounds like you're doing an aftermarket radio if it has "its own fuse". Glad to hear that you found the problem.

The only things that I can recommend is just basic "installation 101" stuff.

Carefully check every wiring connection that was made, that all of them are solid, sound connections and that all are well insulated.

Look for any bare or pinched spots on the wires themselves, and make sure that the radio's ground wire is securely connected to a known good chassis grounding point.

Don't force the radio into place; if the wiring is preventing it from going home, keep rearranging the wires until the radio easily goes back far enough.

 

[sgtsandman]

Depending on how the wiring was installed, it might be worth your time getting new pigtails to connect to the factory harness and the back of the radio. Hopefully, the previous installer didn't hack the wiring or use some of those quick connectors that splice wires together by cutting through the insulation with a thin piece of metal and have a platic clip that covers it all.

If there are wire nuts in there, ditch those and use crimp and seal butt connectors that have shrink tubing with glue in them that seals the splice or solder the wires together and use heat shrink tubing with the glue inside to do the same thing.

Ideally the pigtails with the factory connector and the pigtail with the connector the radio uses is the better way to go.

 

[Kenobi77]

Hooked everything up today and still doesn’t work. Will be breaking out the multimeter again tomorrow.

 

[Kenobi77]

Well, I didn’t even need to break out the multimeter. I checked the internal fuse and it blew again. Looking like it’s time for a new unit.

Fuse in the fuse box is fine.

 

[Kenobi77]

Replaced the unit and looks like I have a short or other issue somewhere. The new unit’s fuse is blowing just like the old one’s did. Any ideas on where to start?

Nothing had changed when the old unit started blowing its fuse. Yes, I followed instructions for the new unit to a t.

 

[RobbieD]

Most likely one of two things.

Check your wiring connections. If you followed how the old radio was connected, you may have followed somebody else's wiring mistake.

Also check for damage to the wiring, especially wires' plastic insulation, in the area behind the radio.

First see if you can get the fuse to not pop with the radio out and disconnected (unplugged). Then plug in the radio, and see the fuse stays OK, and then see if the radio will play, wired up but not installed into the dash. And if so, have it on and playing as you install it to the dash.

 

[franklin2]

You can take a AAA or a AA battery, and touch the + and - wires of each speaker and see if you hear a pop from the speaker. Just to check the speaker wiring. If you can actually see the speaker cone, that is a good way to check polarity of the speaker also. When the + and - are correct, the speaker cone will move outward.