Rewiring a vehicle
From Crankshaft Coalition Wiki
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==Overview== | ==Overview== | ||
When completely rewiring a vehicle there are a few things that must be determined beforehand. First, one must decide if a prefabricated harness will be used, or if a custom harness will be made from scratch. In any case, the harness should be assembled into groups and cut within a reasonable distance to the right length, while leaving extra wire to account for routing. | When completely rewiring a vehicle there are a few things that must be determined beforehand. First, one must decide if a prefabricated harness will be used, or if a custom harness will be made from scratch. In any case, the harness should be assembled into groups and cut within a reasonable distance to the right length, while leaving extra wire to account for routing. | ||
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===If soldering:=== | ===If soldering:=== | ||
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*Good soldering station (don't use an undersized or non-controlled unit; it will slow things down) | *Good soldering station (don't use an undersized or non-controlled unit; it will slow things down) | ||
*Solder (24 gauge 60/40 is good) | *Solder (24 gauge 60/40 is good) | ||
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#Do the same for the whole diagram. You can get software to make your own schematic on your computer. This is where all your notes and line drawing will merge into a single easy-to-read schematic, which will be useful in the future. | #Do the same for the whole diagram. You can get software to make your own schematic on your computer. This is where all your notes and line drawing will merge into a single easy-to-read schematic, which will be useful in the future. | ||
#Next, one last time, ring or continuity check your harness point to point with an OHM meter or ring box. Make sure your connections are correct, and conducting, and conform to your line drawing (you can do both steps at the same time). Once you confirm all is correct, you can power test the system. | #Next, one last time, ring or continuity check your harness point to point with an OHM meter or ring box. Make sure your connections are correct, and conducting, and conform to your line drawing (you can do both steps at the same time). Once you confirm all is correct, you can power test the system. | ||
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| + | ==Fuse requirements== | ||
| + | For heavy draw accessories a [http://www.crankshaftcoalition.com/wiki/Relay_application_guide-_Bosch_relays '''relay'''] is the preferred method of wiring a circuit. Some things that can benefit from a relay: | ||
| + | *Headlights | ||
| + | *Cooling fans | ||
| + | *Fuel pump | ||
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| + | For circuits having a high draw a circuit breaker may be substituted for a large capacity fuse. | ||
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| + | ;Basic fuse requirements (from [[Media:Harness inst painless.pdf|Painless wiring]]): | ||
| + | {| class="wikitable" | ||
| + | |- | ||
| + | ! Accessory !! Amp!!Accessory!!Amp | ||
| + | |- | ||
| + | |Headlight switch||30||Radio (constant)||10 | ||
| + | |- | ||
| + | |Coil||30||Wipers||15 | ||
| + | |- | ||
| + | |Door lock||20||Radio (switched)||10 | ||
| + | |- | ||
| + | |Cigarette lighter||20||Backup/cruise control||10 | ||
| + | |- | ||
| + | | Horn||20||Gauges||10 | ||
| + | |- | ||
| + | |Brake switch||20||Dome/Trunk light||10 | ||
| + | |- | ||
| + | |Power windows||20|| Power antenna||10 | ||
| + | |- | ||
| + | |Turn signals||15||Electric fan relay||5 | ||
| + | |- | ||
| + | |Emergency flashers||15||AC/Heat relay||5 | ||
| + | |- | ||
| + | | Electric fuel Pump||15 | ||
| + | |} | ||
| + | |||
| + | The fuse requirement and wire gauge has to take the accessory load into consideration. Using too small of a wire can let a wire burn even though the accessory load matches the fuse rating. Using too 'big' of a fuse can let a wire burn even if the wire gauge matches the load. | ||
==Testing== | ==Testing== | ||
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The second recommendation is a motorcycle battery (not a big Harley batter, a small hold-in-your-hand Honda-type battery). Install a 30 amp fuse link on the positive, and, (if your meter supports it) use your meter in line to monitor current. At this point you will be doing no "high current testing" so you should be good. If not a motorcycle battery, two parallel connected lantern batteries should last long enough to do some primary testing. | The second recommendation is a motorcycle battery (not a big Harley batter, a small hold-in-your-hand Honda-type battery). Install a 30 amp fuse link on the positive, and, (if your meter supports it) use your meter in line to monitor current. At this point you will be doing no "high current testing" so you should be good. If not a motorcycle battery, two parallel connected lantern batteries should last long enough to do some primary testing. | ||
| − | + | If you must use a battery charger, disconnect ANY electronics you have: CD player, tach, ECU, ECM, alternator, regulator, digital dash displays, and anything solid state to avoid damage. | |
Whatever system approach you take, test for functionality, correct any errors you may find. | Whatever system approach you take, test for functionality, correct any errors you may find. | ||
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| + | ===Testing a brake switch, etc.=== | ||
| + | *Set the meter to the 20 VDC volt scale (or whatever is close to that). | ||
| + | *Ground the negative meter lead, then probe the wires separately. In the "at rest" position- brakes [B]not[/B] depressed- there should be power IN but not OUT. | ||
| + | *With the brakes depressed there should be power at BOTH terminals. | ||
| + | **If there is no power IN, the wire has burned or the fuse blown, or the wire has been disconnected. | ||
| + | **If there's power IN to the switch but nothing OUT with the switch activated, you have a bad switch. | ||
| + | *You can also test the switch using the ohm setting, be sure to disconnect the switch from the wiring first. Connect the meter leads, one lead to each terminal. If the switch is OK, you should have continuity (close to zero) with the switch activated (brakes ON), and infinity with the switch at rest. | ||
| + | **If you have a high ohm reading w/the brakes ON, or infinity, the switch is no good. | ||
==Miscellaneous== | ==Miscellaneous== | ||
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[[Category:Ignition]] | [[Category:Ignition]] | ||
[[Category:Electrical]] | [[Category:Electrical]] | ||
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