What I’m Up Against, Electrically Speaking…

The wiring diagram I ordered last week hasn’t come in yet so I wasn’t able to fully dive into debugging the electrical system today. I was, however able to take stock of the situation and find out what I’m up against.

But first, rubber plugs…

The day started out with opening up my new body plug kit:

Whenever there is a hole in the body of the Mustang (to let a bolt, wire or other item through) there is generally a rubber plug that fits over the hole to keep moisture out. After almost 50 years, you can imagine the condition of most of the rubber plugs on the Mustang. If you imagined “hard as a rock and mostly useless” you’d be right:

That’s the plug I took out of the trunk a few months ago that allows access to the rear shocks. The Mustang has two rear shocks and two holes, but nevertheless, there was only one remaining plug. After I started looking elsewhere on the car, I found a number of other places where plugs were missing so I decided to get a whole kit and will eventually get them all replaced.

The new plugs are nice and pliable and are nicely labeled with exactly where they need to go. These two were destined today to be installed in the trunk:

Then it was time for battle with the electrical system. I started easy by converting the light inside the ignition switch module to an LED:

…and re-installing the ignition switch. I still don’t have the special installation tool yet, so this install was just as bad as the last one and the switch is still loose. I’ll have to live with it until I order more parts and can buy the tool.

And then I started testing things. Here’s what I found:

Working:

• Ignition switch
• Ignition switch light
• Transmission gear selector light
• Outer headlights (low beam only)
• Parking lights
• Instrument cluster lights
• Battery gauge
• Oil pressure gauge

Not working:

• Outer headlights (high beam)
• Inner headlights
• Dome light
• Brake lights
• Windshield wipers
• Turn signals
• Emergency flashers
• Horn
• Gas gauge
• Temp gauge

I don’t have the washer fluid reservoir installed yet, so that didn’t get tested. I also didn’t test the cigarette lighter because it didn’t even occur to me to do so until this very minute.

So, I’m starting with less than half of my electrical system working. Not an auspicious beginning, but then again if everything just worked what fun would that be?

Without the wiring diagram, I decided to keep attacking the easy stuff. The hi/low headlight beam switch (which is on the floor, not on the steering column) was in obvious disrepair with a crooked top and (at best) mushy feel:

Thankfully, I had a brand new switch that I’d ordered a few months ago ready to install:

And with that, I had functioning hi/low beam headlights – but only for the outer headlights. The inner headlights (which are high-beam only) still don’t work for some reason.

Then it was on to the fuse box to see whether or not I had any blown or missing fuses. I started by simply taking my multi-meter and doing a continuity check between all of the fuse leads.

And suddenly – dome light!

A quick test of the dome light system showed that the dome light worked:

• When the passenger’s door was opened
• When the driver’s door was opened
• When the dome light switch is toggled on the dash

All I had done was slightly bump one of the fuses and caused it to rotate slightly – indicating a poor connection between the fuse and the fuse box panel lead.

Further futzing with the fuse box also yielded a half-way functional emergency light system. If that fuse is futzed with just right, I can get the front flashers to blink, but not the back ones.

With two things fixed simply by wiggling fuses, it’s pretty clear that I need to clean the leads on my fuse box. I unbolted the fuse box from the firewall:

and took a closer look:

You can see that the leads are rusty and tarnished – especially on the small fuse slot that I removed the fuse from.

So, I’m going to try to clean the leads. My research has informed me that either this has no chance of working or is really easy to do with a sandblaster. Since I don’t like the first option and don’t have a sandblaster I’m going to go with an alternate approach:

That’s a small round sanding bit that I have for my Dremel tool. I’m hopeful that once I take the fuses out I can get that between the leads and get them cleaned off.

Stay tuned for reports on how well the cleaning-by-Dremel idea worked…