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Old 06-28-2017, 11:15 PM   #1
dmjlambert
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fuse panel detailed description or diagram

I have searched but not found this. Has anybody made a picture or diagram of the fuse panel for 67-72 that describes in detail what each fuse is for and whether it is always hot or switched at the ignition, and what the terminals are for and whether they are always hot or switched? I can't really make sense of most the labels that are printed on the fuse panel, and if I manage to figure one out, I can't retain that in my memory for the next time a few weeks or months later, when I go try to figure the next thing out. So, looking for some sort of detailed reference guide. There are some I understand such as IGN UNFUSED.
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Old 06-29-2017, 04:45 PM   #2
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Re: fuse panel detailed description or diagram

I think it would be better to trace the wiring harness from the battery positive post to the fuse box for a better understanding of how the system works.

Positive current electricity begins at the battery Plus post with the large cable to the starter solenoid. In addition there is a fusible link from there to a junction on the right fender to protect the key off electrical circuit.

From the junction a 12 gauge red wire continues across the top of the radiator and down below the left headlight to the main junction of the positive power wires.

Shown below are the points I have mentioned. The main junction includes wires from the battery, the alternator, the regulator, and the main cab feed wire to the firewall junction block.



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This is the firewall junction block showing the 12 gauge red power wire for the cab. Notice the large purple wire for the starter solenoid and the cloth covered wire which is the resistance wire for the ignition coil.

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The green and blue wires are the temperature sender and the oil sender wires respectively.

Next we get into the cab and follow the large red wire up the left side of the diagram. Notice it joins three other wires which are the power feeds for the horn relay the, the ignition switch, the headlight switch and the fuse panel.
All these are full time key off power wires.

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Remember the large red wire is key off power to the fuse panel and it powers the things which do not require the key to be on to operate.
The stop lights
The hazard light flasher
The dome light
The parking lights.
The cigar lighter terminal.
The backup lights fuse.
The radio terminal.
Here's a view of the wiring for the fuse panel. It's the same one shown above.

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Notice the large red wire from the junction.

The main attachment point feeds the fuses for the items mentioned just above which do not require key on power. The primary output wire for these items is the orange wire, which feeds the stop/taillight fuse, the dome light fuse, and the headlight switch, for the parking and dash cluster lights.

The dash cluster lights are fed from the headlight switch through the variable resistor in the headlight switch, back to the fuse panel via a green wire, to the Pnl Lts fuse.

I think that's all for the key off fuses.


Looking at the diagram for the key and headlight switches we see a 12 gauge brown wire and a 12 gauge pink wire on the key switch. The brown wire is the accessory wire and it goes to the fuse panel to feed the wiper fuse, the turn signal flasher, and the heater, AC fuse.
(NOTE)- 1967 trucks did not have an accessory key switch and no brown wire.

The pink wire from the key switch goes to the junction In the denter of the diagram and tees off for the fuse panel and the ignition coil + terminal.
The pink wire at the fuse pane feeds the IGN Unfused terminals and the cluster feed fuse.

Here is a diagram of the key switch and the headlight switch.

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And here is a fuse panel with the fuses and terminals labeled. They can vary
slightly.

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I'm sure I've missed something so if you have any questions let me know.
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Old 06-29-2017, 09:20 PM   #3
dmjlambert
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Re: fuse panel detailed description or diagram

Thanks, great info. I'm going to read the heck out of this and study.
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Old 06-29-2017, 11:11 PM   #4
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Re: fuse panel detailed description or diagram

DMJLAMBERT, you are in the best of hands with VETTEVET, patient, tons of info, kinda like one stop shopping for free!! Enjoy
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Old 07-31-2017, 11:52 PM   #5
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Re: fuse panel detailed description or diagram

OK, so I searched and figured out nobody has done this before, perhaps nobody was interested other than me. I guess I'm a visual person. I mapped it out.

Switched and dimmed for dash lights means this section has 0 to full current depending on the headlight switch and dimmer position.

Return from fuel level sensor means this is attached to the ground side of the fuel gauge, and the wire that plugs into it supplies ground through the float's variable resistor. This doesn't really belong on a fuse panel, as it is only a connector, but perhaps it was considered convenient.

Always On means this always has battery voltage regardless of position of ignition switch.

Accessory means this has battery voltage in accessory and on positions of ignition switch.

Key On means this has battery voltage in on position of ignition switch, but not in accessory position.

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Last edited by dmjlambert; 08-01-2017 at 12:06 AM.
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Old 08-02-2017, 11:19 AM   #6
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Re: fuse panel detailed description or diagram

Thanks for your effort, dmjlambert. The fuse panel labels have always been cryptic to me, too. Now it's clear to me that each of the 4 powered section has at least one open terminal for add-ons. Nice.
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Old 08-02-2017, 12:58 PM   #7
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Lightbulb Re: fuse panel detailed description or diagram

I added this fuse block into my 71.
It sits to the right of the column. It gives me plenty of fusible space for extra's. I tied it into the fused connection on the main block.





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Old 10-12-2018, 02:39 PM   #8
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Re: fuse panel detailed description or diagram

Apologies for resurrecting an old thread.

What does the CLSTR fuse operate?
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Old 10-12-2018, 03:17 PM   #9
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Re: fuse panel detailed description or diagram

top right fuse is cluster illumination, one below it is fuel and temperature gauges and warning lights
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Old 10-12-2018, 08:03 PM   #10
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Re: fuse panel detailed description or diagram

Quote:
Originally Posted by dmjlambert View Post
top right fuse is cluster illumination, one below it is fuel and temperature gauges and warning lights
Thanks!! That's brilliant! Just need to get rid of that silver foil around the fuse now
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Old 11-07-2018, 09:18 AM   #11
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Re: fuse panel detailed description or diagram

The 18g black wire in the first picture that runs the firewall into the junction block. Is it needed? I donít think I have it.
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Old 11-07-2018, 10:36 PM   #12
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Re: fuse panel detailed description or diagram

The 18B wire and the 18B/W wire with fuse holders in them are for the ammeter gauge, if you have an instrument cluster with gauges.
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Old 11-08-2018, 06:19 AM   #13
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Re: fuse panel detailed description or diagram

Thank you, I have the factory cluster but will probably have to use some aftermarket gauges. Iím on the final stretch of the build but Iím having issues with the electrical portion. One headlight dim, only left blinker works, wipers work on occasion. Any options besides a $500 painless harness? Upgrade fuse block? Thanks
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Old 11-08-2018, 10:34 PM   #14
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Re: fuse panel detailed description or diagram

It depends on your goal. If the insulation on the wires is not cracking or melted and wires are not corroded, you can just troubleshoot problems one at a time until resolved. Post new questions as you think of them in the Electrical section and somebody who knows about that particular topic will help. Pictures are useful.

In my case the wiring appeared to be in good condition but I had a dozen wires in various locations eaten by rats, and I had 1 melted connector for the heater fan switch. I soldered in sections of new wire and used heat shrink tubing to fix the wires, and put a new-to-me used connector on, and it was back to 100%.

Most of the switches and bulbs were bad in my truck, that would not have been fixed by a wiring harness. I just tested and replaced all the bad lights, such as the headlights and turn signal lights. And replaced the various switches, such as headlight, hi-lo dimmer, and turn signal switch. Some people just replace all the wiring because they are doing a complete restore, and replacing everything else so might as well replace the wiring.
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Old 11-08-2018, 10:40 PM   #15
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Re: fuse panel detailed description or diagram

There are 2 types of factory instrument clusters. Some trucks have a cluster with speedometer, fuel, temperature, oil pressure, and ammeter gauges, and other trucks have a cluster with speedometer and fuel gauges and the rest of the indicators are warning lights. It is possible to change from one instrument cluster type to the other, but some truck wiring and the pinout of the cluster connector would need to be updated. If you become a premium member here on the forum you can post want-to-buy ads in the parts section. I have done that for several items, including an instrument cluster and some electrical connectors that another forum member cut out of his old stock wiring harness for me.
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Old 11-08-2018, 11:10 PM   #16
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Re: fuse panel detailed description or diagram

Thank you for the reply! Iíll just have to troubleshoot each one and possibly replace things as needed. Iíll post further electrical issues in that section. I have the second type of cluster. Speedo, fuel and warning lights. Not much works on it after my swap.
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