Rewiring a vehicle

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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:===
 
 
*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==
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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:
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*Headlights
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*Cooling fans
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*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]]):
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{| class="wikitable"
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|-
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! Accessory  !! Amp!!Accessory!!Amp
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|-
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|-
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|Power windows||20|| Power antenna||10
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|-
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|Turn signals||15||Electric fan relay||5 
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|-
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|Emergency flashers||15||AC/Heat relay||5
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|-
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| Electric fuel Pump||15 
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|}
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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.
  
Lastly, 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.
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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.
  
==Miscellaneous==
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=
One must realize that many times you will supply power to a circuit (i.e. tail lights), and other times you will supply a ground, as the circuit have power supplied directly to them, and the ground is what is switched. This is very common in courtesy lights that are grounded when the door switch is activated.
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Sometimes you must use existing wires (as when they go from the dash, up the A-pillar, across the top, to a courtesy (interior) light. These are seldom removable if you have the headliner in place. Use a test device to be sure there are no shorts or 'opens' (broken wires).
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If you are changing from 6 to 12 volts (a very good idea), your new wire does not have to be as large as the original, as the current will only be 1/2 the original. This can be important when buying wire in several colors. You can often do much of the wiring using 14ga wire, or even 16ga, but be sure to determine the current draw before committing to a particular gauge of wire. Also, if you use LED lights, the current is minscule! And, they generate no heat to speak of.
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Sometimes a custom harness will be cheaper, especially if you want to use factory color codes.
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Furthermore, it is suggested that a maxi fuse is installed rather than a fusible link. A lot of this is personal preference. However, it is too easy to pop a new maxi back into the socket and avoid the REAL problem -- what took it out? A fuse link MUST be cut, repaired, soldered and heat-shrunk back into place to be repaired. This will motivate you to look into WHY it went out.
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Fuse links, unlike fuses, do not just blow -- something major is wrong! And, it was wrong long enough to melt wire -- unlike a 5 amp radio fuse that sees a 7-amp spike and opens a few times a year. It took a 50, 70 or 100 amp short of a few seconds/minutes to melt the link -- not a small issue. Find out why!
 
Fuse links, unlike fuses, do not just blow -- something major is wrong! And, it was wrong long enough to melt wire -- unlike a 5 amp radio fuse that sees a 7-amp spike and opens a few times a year. It took a 50, 70 or 100 amp short of a few seconds/minutes to melt the link -- not a small issue. Find out why!
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In either case, a maxi and fuse link do the same job -- a 70-amp maxi is the same as a 70-amp link. What is important on either is to never install them inside a passenger compartment. They do their job by heating and melting, and can cause fires to interior parts, melt plastic parts, and create toxic fumes in a closed compartment. Always install them in the engine bay away from fuel, hydraulic, or other flammables.
 
In either case, a maxi and fuse link do the same job -- a 70-amp maxi is the same as a 70-amp link. What is important on either is to never install them inside a passenger compartment. They do their job by heating and melting, and can cause fires to interior parts, melt plastic parts, and create toxic fumes in a closed compartment. Always install them in the engine bay away from fuel, hydraulic, or other flammables.
  
While some wiring harnesses recommend the main power come off the starter live connection, running the wire straight to a single insulated battery terminal post can be a better way to go. Such a case would be an off-road vehicle where water or mud could cause problems if the main power wire is connected to the starter.
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While some wiring harnesses recommend the main power come off the starter live connection, running the wire straight to a single insulated battery terminal post can be a better way to go. Such a case would be an off-road vehicle where water or mud could cause problems if the main power wire is connected to the start
 
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[[Category:Ignition]]
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[[Category:Electrical]]
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Latest revision as of 06:10, 30 December 2024

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