electrical help needed

[framedoctor]

My father in law passed and left my kids a 1988 Eagle wagon with 60,000 miles. The car ran fine, then I decided to upgrade the stereo for the kids which worked well for a few weeks until one trip we turned on the defroster switch which in turn started the stereo wires smoking. I will start by saying I am an electrical know-nothing.
I removed the stereo, the car harness was unaffected, and then removed the defroster switch (which after the stereo was removed just made a constant buzzing noise). Now, the fan does not blow on high, the gas gauge and the coolant gauge needles max out on high when the car is started. I also discovered that I can now start the car without the key (no interlock?)
Is there anyone that can help me? Does it sound like a ground issue? Does it make sense to anyone? any help would be appreciated as my kids are pretty bummed now.
Dave

[Canoe]

Given you started smoking wires to the stereo, there's been some heat generated (likely shorted something).

So anything touching or near them could be heat damaged. And anything upstream/downstream of the current flow that generated the heat. Be it other swtiches, connectors, insulation melted, even the fuse box, and may be malfunctioning, or shorting which could cause more damage, even an electrical fire.

You need to identify where the stereo wires melting took place:

• physically, to see if the smoking/melting wires have damaged any wires, switches, devices, and
• everywhere those wires run to, looking for damage due to the high current that caused the high heat

But first, I'd recheck all fuses.

I'd unplug the new stereo from the car's harness, to take that out of the mix. Get the car working correctly first.

This may be something best left to someone knowledgeable, so you avoid the fire risk. Be it sitting or while driving down the road.

Not uncommon to be able to start an Eagle without the/a key. Less so with only 60 on it.

[framedoctor]

The stereo is out and the defrost switch is out. all wire damage was on the harness nearest the stereo. I have inspected the wires leading back from the original stereo harness and from the defrost switch harness and so far no seeable damage. I will have to locate the fuse box (not real sure where it is) and look through it. I have also read that a bad silenoid can give electrical feedback and mess with gauges?

[framedoctor]

So the ignition interlock problem is not a problem, apparently the Eagle has a switch below keyhole.
Here's more of what is a problem. My temp and gas gauge are fine until I turn blower on or headlights, then the gushes go full up. Also, the headlights do not light up when switch is pulled.
Can someone tell me where the fuse box is located?

[rmick]

Fuses are located on drivers side up under the dash at the firewall.

[rmick]

This may also help http://amceaglesden.com/guide/1988_Large_Electrical_Schematics_-_Much_applicable_to_other_years.

[framedoctor]

do I have to remove the dash to get to the fuse box?

[vangremlin]

No, you don't have to remove the dash.  It's below the dash, just to the left of the brake pedal.

Good luck!

[framedoctor]

Yeah, Im a novice at cars but with electrical issues----this car may never get fixed. for sale, 1988 Eagle wagon, mint cond., 60,000 miles

[Canoe]

Throw some photos up.
Perhaps we can figure it out.

I'd go as far as don't leave it sitting with the pos on the battery DIS-connected, just in case.

Question will be, was there something wrong with the stereo install, with the defrost or defrost switch, or something else...

But after the large current draw, other damage is on the table.

By defrost switch, I assume you mean the switch to power the rear window defrost? If so, does the wires that go to the grid on the window look good? No shorts? No repairs to the grid that would reduce it's resistance so it drew more current than usual?

[framedoctor]

When I took out the factory stereo with acc on,  the defrost switch made a constant buzzing sound until new stereo was installed. The new stereo was fine for several weeks until the rainy night my wife turned the defrost toggle on, that when the smell and the smoke started. upon tearing things apart the wires nearest the harness into stereo were fried. I removed the new stereo and the defrost switch again started buzzing so I removed it from its harness. There was continuity between the ouside pins of the lower three in pic. I also attached a pic of stereo harness with melted wires. It was a ground wire, accessory wire and power antennae(not equipped)

[framedoctor]

in regards to the burnt harness, the red accessory wire was on a fuse which did not blow as well as the yellow battery wire. The power antenna wire was not connected to car harness. So im guessing that the heat originated in the ground?


Here is the car if it helps!! haha

[Canoe]

I'd go as far as don't leave it sitting with the pos on the battery DIS-connected, just in case.

[Canoe]

... So im guessing that the heat originated in the ground? ...

Heat occurs where there's current flow. The higher the current, the greater the heat. Hence high current loads have thicker conductors to handle that current AND insulation that can handle the heat from that current.

Can't tell from those photos where the origin was. Likely from current within the melted wires, but another heat source may have melted their insulation, allowing them to short to something and then they had too high of a current through them.

Is there any sign of heat damage to the dash where the radio and that switch was? In behind it? Use camera or mirror & camera.

[framedoctor]

the only damage visible was near stereo. I followed the car harness and defroster harness as far back as I could and see no damage. There also was not heat damage to dash or inside of dash. I really dont want to remove the entire dash I was hoping someone would say its a bad ground with the headlight/gauges issue. The solder joints inside the defroster switch look like they were reflowed or were hot enough to reflow?