electrical help needed

[mudkicker715]

there is better is what I am getting at. applying to existing connections yes. mating surfaces no. so with dielectric grease you drown the top and surrounding area. however somthing like kopr-shield actually improves a connection and can be applied before making any connections to ground. than you can also drown the area making a better connection and help prevent corrosion.

[framedoctor]

Hear you on that, I added as it also sounds like my problem with headlight and gauges. I just dont know how to locate the ground problem.

[framedoctor]

Can anyone tell me in the picture of wiring diagram it shows "ground to s119" What does that number refer to and how can I find where s119 is?

[Canoe]

there is better is what I am getting at. applying to existing connections yes. mating surfaces no. so with dielectric grease you drown the top and surrounding area. however somthing like kopr-shield actually improves a connection and can be applied before making any connections to ground. than you can also drown the area making a better connection and help prevent corrosion.

If it works as you say, kopr-shield shouldn't harm a GROUND connection, and could be of benefit if it stays there to protect against corrosion - it would not be an acceptable substitute for a connection cleaned of corrosion (corrosion has resistance, and encourages more corrosion). As it is conductive, it would be unsafe to use on a positive connection, as if it creeps it could result in that connection shorting to ground.

For the most protection, dielectric grease is applied to mating surfaces - before connection - positive or ground, to prevent corrosion between the contacting surfaces. Not only does corrosion resistance steal voltage, enough corrosion with enough current flow, can generate enough heat to cause a fire. Note the Fluke instructions that include making the terminal "shiny" prior to application: remove 'trivial' surface oxidation for a superior connection. (Carrying both white and pink erasers was a given when doing IT hardware support.) Applying enough dielectric grease to a connector prior to assembly, also should cover the wires back to the insulation, inhibiting corrosion in those wires too. Stuffing some in/onto a connector after it's together is better than not doing that, but it is a considerable reduction in corrosion protection. The exception is a crimped connection, which should be as clean, shiny and dry as possible prior to crimping. (Proper crimping is a subject all on its own...)

I have yet to encounter a connection degraded, voltage or current, through the use of dielectric grease.

Dielectric grease on the spark plug wires has stopped many shorts in high-splash conditions, on a number of vehicles I've worked on. It's eliminated battery connections issues, provided it's applied prior to developing corrosion in the cable. After having to go back and clean or completely redo various connections too many times, I now use dielectric grease on positive, ground and in connectors, wherever possible. I've even applied it to spliced connections prior to encasing them with heat-shrink tubing. Saves me trouble and time fixing or chasing after problems.

[Canoe]

I'm very curious to know why that defroster switch was buzzing.
And if the high/low headlight switch (mounted forward/down from the lever that controls it) is working or showing signs of heat damage.

Speculating (not enough info to properly support this yet): I'm wondering if that defroster switch was somehow using the stock stereo's harness for some or a meaningful portion of its ground due to a degraded ground path that switch and hence defroster current was expected to use. Then if the new stereo install didn't provide, or adequately provide, enough of a ground path to work in parallel to a degraded defroster switch ground path, then turning on the defroster energizes the rear defroster ribbon, leaving its potential current draw searching for the easiest path to ground. Doesn't explain why/how those wires in the new stereo harness got that current draw, unless some how they shorted. I need to read back through and see if the stereo was running when the defroster was turned on, and if the stereo worked after that second try at the defroster. 

[framedoctor]

The stereo was on at the time the defrost switch was turned on and was working while its wires were smoking. Based on the condition of the burnt wires it wouldnt have stayed on much longer.

I dont know if i noted that on the stereo harness both the battery wire and accessory wire had in line fuses that did not trip.

[framedoctor]

Does anyone know the best way to remove the dash so that I can start searching for bad wires?

[Canoe]

Does anyone know the best way to remove the dash so that I can start searching for bad wires?

PITA - leave that as a last resort. Remove the tray above feet if your '88 has such, and the lower/underside dash covers if they have them, and then you can look up under, by sticking your head in there, using a mirror, camera/phone, fibre-optic viewer, etc..

[Canoe]

The stereo was on at the time the defrost switch was turned on and was working while its wires were smoking. Based on the condition of the burnt wires it wouldnt have stayed on much longer.

I dont know if i noted that on the stereo harness both the battery wire and accessory wire had in line fuses that did not trip.

Now it's getting weird. The harness supplied with the stereo should be rated for its current draw, yet it melted down. And that takes a high current, yet the supplied fuses didn't blow. And the stereo continued working while that high insulation-melting current was travelling on those wires, so it's still getting a voltage it's happy enough to work with. With correctly speced wires, such flow starts with a voltage difference which is typically a Positive supply voltage (or a high enough drive output) shorted to ground, either directly or through a rather low resistance path (like a defrost ribbon); which typically drops the available voltage - yet the stereo kept working. And if the stereo's rail voltage dropped enough that the volume dropped, it wasn't enough that it was noticed (or didn't seem material?).

Have you checked the in-line fuses in the stereo harness to see their values, and if they're actually fuses and not placeholders?

I wonder if your defroster switch switches positive, ground or both. If you look at your rear defrost ribbon electrical attachments, do both wires look like they're wires returning to the front of the vehicle, or is there perhaps one that is attached to the body there for a ground? (at one of the hinge bolts?)

In your photo I'm seeing a melted blue wire and a melted orange wire, yet there seems to be a third collection of strands in that mix. From your drawing in another thread, under From Stereo I'm seeing Red - ACC/IGN, Yellow - Battery, and Blue - Power Antenna, and a Black - Ground. Is it correct that ACC/IGN, Power Antenna and Ground melted? Do you have a photo of that harness that shows all sections that show damage, even if minor?

(It's almost as though the Defroster circuit somehow managed to pull both Positive and Ground off of the stereo's Positive and Ground rails..., running both stereo & Defroster in parallel through that stereo harness.)

Lots of fun, as we're trying to determine what caused the problem, vs. what problems may also now present after damage from that high current flow.

Headlights: confirm that when the switch is pulled out, neither low headlights nor high headlights work? What about the parking/running lights? Dash/instrument lights & dimmer?

p.s.
On searching under the dash.
Before you start that search, you should check the high/low headlight switch (not its lever) and the fuse box.
You can pull the connector to the high/low switch and check continuity of the switch in both positions; hope the switch is already adjusted to the lever's travel properly.

[rmick]

You can pull the instrument cluster out with out pulling the dash This would get you a good visual access to wires.

[framedoctor]

Ok thanks, I'll try. Any idea how to remove the headlight switch?

[framedoctor]

Canoe, the fuse for acc was a 5 amp and the battery wire was a P10A250v.

Also when looking at the stereo harness damage to me it appears it was the ground wire that heated up and then melted everything next to it

[framedoctor]

in this picture it shows a wire block located behind the brake assist on firewall, maybe opposite of where headlight switch on inside. it looks and feels like there was melting where the wires go into it? does anyone know what this is?

[Canoe]

Canoe, the fuse for acc was a 5 amp and the battery wire was a P10A250v.
Also when looking at the stereo harness damage to me it appears it was the ground wire that heated up and then melted everything next to it

Ah ha!
The fuses not blowing supports that: over-current on the ground, no or regular current on the others.
Does that mean there's no sign of other damage along that harness?

Which brings us back to the possibility

... I'm wondering if that defroster switch was somehow using the stock stereo's harness for some or a meaningful portion of its ground due to a degraded ground path that switch and hence defroster current was expected to use. ...

Before you go pulling anything or do too much work tracing wires, you need to check that fuse box and the wires around it. Also the high/low switch.

Ok thanks, I'll try. Any idea how to remove the headlight switch?

The headlight switch (parking, headlights, .) or the high/low selection switch?
If the high/low, remove the connector going to it and get a visual on the switch. All the one's I've seen are white, and you can usually see over-current damage as melting or black. Check the continuity of the pins with the two positions selected by the lever. Often if there's heat damage it won't select properly; which can also happen if the switch has slipped in its mount so the lever may need to be adjusted first, which is actually an adjustment of the physical position of the high/low switch along the steering column. Hate to see you pull a working switch.
Check the eaglepedia for the TSM and look at the parts diagram to try and see the layout.
For the light switch, it's knob comes off (don't force - there's usually a clip at the back of the knob to press in to release it's tension on the switch shaft), there's a flat-nut holding the switch in, with the switch being a nasty reach up from behind. I've done it, but don't remember more than that.

Here's a curious one. With the new stereo pulled out, if you put the defroster switch back in now, does it buzz?

[Canoe]

in this picture it shows a wire block located behind the brake assist on firewall, maybe opposite of where headlight switch on inside. it looks and feels like there was melting where the wires go into it? does anyone know what this is?

The colours should match up with the wiring diagram.
Photo from pulled-back to better show the location in context?

With melting signs there, it doesn't necessarily mean it's to the point of not working or a risk. (BUT, it is enough of a risk that until this is sorted out, I wouldn't leave the battery connected, except while you're checking function)
Need to check the fuse box and that high/low switch.
Need to redo that ground connection under the hood to ensure there's a decent body ground.

Where we think we are now?: over-current on the ground of the new stereo harness melted it, and acc/ign and pwrAnt of that harness; the car's harness that plugged into does not show any heat/melting/burning damage (traced back to the fuse box?); defroster wiring or switch likely source of current that melted that ground wire; searching for other damage to explain the resulting failures/behaviour.