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| | | | Joined: Dec 2007 Posts: 30 Apprentice | | Apprentice Joined: Dec 2007 Posts: 30 | What amp fuses were stock to the 47 1/2 ton firewall fuse box?? Was the heater switch fuse a higher amp or are they all the same?? Thanks
Last edited by mazzer; 08/20/2008 6:12 PM.
| | | | | Joined: Feb 2004 Posts: 29,746 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,746 | Fuses are designed to protect the wires, not the end item that's being operated. Things like heater motors will draw more current than other accessories, so the correct size fuse will carry the full load of the item being operated, plus about a 20% overload. The wire should be sized appropriately. For instance: Tail light circuits generally have #18, or maybe #16 wires, and they're protected with either 7 1/2 or 10 amp fuses, depending on how many bulbs are burning. A heater motor will probably have a #12 wire, and carries about a 20 amp fuse. If a #10 wire is fused, it's probably going to have a 30 amp or bigger fuse, because the wire is capable of carrying that much current without overheating. I'm not sure what size fuses were original equipment, but use a little common sense and be sure the wires are protected from over-current situations while still being able to carry enough current to operate the accessories they supply.
Jerry
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| | | | | Joined: Dec 2006 Posts: 1,464 Shop Shark | | Shop Shark Joined: Dec 2006 Posts: 1,464 | I'm a little confused by your question. The '47's didn't have a firewall fuse box. The only fuse shown in the wiring diagram is mounted on the light switch.
How many fuses do you have in your firewall box?
The '48 and '49 trucks had a 5 slot fuse panel. All the fuses were 20 amps.
The 50 and up AD's used a 2 position fuse panel for stop and tail lights, both 20 amp fuses.
Hope that helps. | | | | | Joined: Jan 2008 Posts: 4,960 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,960 | You can tell by the fuse holder what fuse it should have. The old SFE fuses got longer as the amperage went up. | | |
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