A few weeks ago, I rotated the headlight switch clockwise and that caused a short that allowed a wire to release it's smoke. Today's post covers that resolution, with some expected twists and closes with a plan to update the fuse box.
Poof
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| 72 bus wiring diagram |
So, I dug into the interweb. I found another person who had the buzzing noise from their flasher relay and they discovered the root cause was that the dashboard did not have power. Sounds about right, I suppose, so we remove the dash to see. The dash removes with 4 screws. If you are fortunate enough to have the vent and oily-smelling-air controls, you may need to manage them first. I have the older style controls which originally had the little colored spring-loaded clips. Of course, Hapy didn't have the colored clips, and still doesn't. Anyway, remove anything from the vent control levers which impede the dash removal, remove the 4 screws and detach the speedometer cable. Then, the dash lifts straight out (a little diagonal) to the steering wheel. At that point, I rotate it so the face points to the floor. To me, this puts the least pressure on the wires while exposing them for me to see. From here, I could see that the black wire from fuse 12 that delivers 12V to the dash had it's plastic casing melted off. How and why that wire fried rather than popping the fuse, I don't know. The fuse was and is still there, it was relatively new (like, in the last 5 years), the right rating and it was seated properly.
Clumsy
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| 1 fried wire |
Knowing which wire needed to be replaced is a great first step. Getting that wire replaced without negatively impacting anything else in the original electrical system, however, is a virtually impossible task. Such was the case this time. First, I pulled the wrong wire out of the fuse box, and as I did, I dislodged a couple of fuses. Then, I got the wire back in and dislodged some other ones. Finally, I found and removed the bad wire from the fuse box, bumping a wire out of the high-beam relay holder as I did. Neat.
I formed a new multi-female-spade-connector wire, using the fried one as a pattern. With a multi-meter, I confirmed the connectivity between all of the end points had 0 resistance and returned to Hapy's driver seat. I plugged the wire into the tabs on the dash, and dangled it behind, finding the tab in the fuse box. Again, I unsettled a few fuses, but once they were in place again, I started testing. First, I confirmed that the running lights and headlights came on. It being daytime, I could tell the lights were on, but not that the headlights were the high-beams. I turned the key to run and the buzzing was gone. The turn signals worked, the hazards worked, and continued to work when I turned off the key. I even test started the engine to prove things were good. What I didn't test: the wipers. It seems that when I was messing around with the fuses, I failed to reseat fuse 11 (which controls the wipers and the rear defogger) after reseating what felt like all of the others -or- another wire fell off. I didn't discover that the wipers didn't work until I tried to take a drive at night in the pouring rain. So much fun. I don't think Hapy likes the winter weather very much; he does seem quite persistent in staying in the driveway.
About Had It
So, after spending so much time diagnosing issues only to discover the issue was the 50+ year-old fuse box or really the style of fuse used in the 50+ year old fuse box, I have decided to look into replacing it. I say that because the wire that fried was on a fuse that didn't blow and the fuses are in the box so loosely now they become disconnected simply by brushing past them. Based on my research, I understand the fuse-box layout / purpose to be this table below. I will replace with a simple 12-slot 12-independent-circuit box that uses spade fuses instead of the old buss style. It will ultimately use the same circuit numbers as before for all of the things I am keeping (never had ambulance fans, nor ignition buzzer, nor interior lights). Plus, it will include things I need, like radiator fans and the fan for the heater.
| Fuse # | Original Purpose | Changed Purpose |
| 1a | front running lights, license plate light | |
| 2a | rear running lights | |
| 3b | passenger low headlight | |
| 4b | driver low headlight | |
| 5b | passenger high beam | |
| 6b | driver high beam | |
| 7* | open? looks like it was for ambulance fans | radiator fans |
| 8* | emergency flasher and interior light | emergency flasher only |
| 9* | ignition buzzer, rear interior light | interior heater fan |
| 10# | horn, brake light warning switch/light | |
| 11# | windshield wiper, rear defogger | plus the windshield washer pump |
| 12# | dashboard, emergency flasher | |
| rear backup light |
a: supply-side from light switch
b: supply-side from headlight flasher (dimmer relay)
*: always hot
#: switched
&: inline fuse not in fuse box
I will be adding a master circuit-breaker as well back by the starter (where the main 12V source for the fuse box comes from) so there is a safety on the entire #30 circuit that goes to the ignition and the head light switch via the supply-side of the always-hot fuses. I do not know when I will get after this, though. The joy I have had since removing the rat's nest of wires for the engine control has been significant. The wires for the original bus have their problems, and I will be replacing some of the runs (particularly the rear tail lights), but for the most part, they have been up to the task. I just need to find a way to stay somewhat dry and maybe a little not-freezing so I can get after it. Since it is January, I recognize my opportunities for something this big will probably not appear for a while. Still, I can't keep letting smoke out of the wires, and I would very much like to get Hapy out of the driveway for a safe drive-around before spring. For the Pacific NorthWest, that starts with getting the wipers working again and then getting the high-beams turned off.
That's it for today. Thanks, as always, for following along-
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