Dash wiring and testing

m0par0rn0car

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I have a 69 fury 3 that i’m making a wiring harness for behind the dash but don’t want to go through all the work for something to break. Is there any way to bench test the gauges (ammeter, fuel, temp) as well as the switches (washer, wiper, headlights, panel dimmer, and 4way)? I’m planning on putting in a solid state dc-dc 5v converter as well as voltage regulator just to be on the safe side and have things operate well. I hate wiring and really only want to do this once so any way to check the components I have before they go in the car would be great
 
The fuel and temperature are fairly easy to test.

You'll need a good source of 5 volts. With some work, an old computer power supply can be used (google "convert computer power supply to bench power supply for directions) or rig something up with your new voltage limiter.

Then you need some resistors or you can spend a few bucks on a cheap Decade box like I did. More info here:
c-3826 tester for gauges and sensors

For the switches, the first thing to do is a simple continuity check with a multimeter. That will give you a good idea if they work at all, but the real test is when you put some current through them. I'd rig up an old headlight and a car battery or something like that and try the switch that way. To test it further, you can do a voltage drop test across the switch while you switch the headlight on.

Nobody ever watches this but I persist in posting it because it's good info about voltage drop.



The ammeter is a tougher one to bench test, although it can be done. Honestly, doing a bypass under the hood will take a lot of the current load off the power wiring under the dash and through the bulkhead disconnect. It will make the ammeter pretty much useless though. Here is a good explanation of the hows and whys. Some considerations about the charging and wiring upgrade and your worries about It's important to use a fusible link if you do that mod.
CBarge did a thread with better pics on the way it's done. Underhood Ammeter Bypass Read the Charger link first though.


Here's how I rebuilt, one wire at a time, the wiring harness in a '53 Chrysler. Just a piece of plywood and some finishing nails. I've been factories where they build wiring harnesses for high end military electronics and this is the same way they do it.

FMfEJOl.jpg
 
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Here's how I rebuilt, one wire at a time, the wiring harness in a '53 Chrysler. Just a piece of plywood and some finishing nails. I've been factories where they build wiring harnesses for high end military electronics and this is the same way they do it.

View attachment 386758
I worked with technicians in a lab that did a complete wiring harness for an F-14 Tomcat the way you did with plywood and finishing nails.
The jig was about 40 feet wide and 80 feet long. The harness was transferred into a laboratory so that we emulated the length of the aircraft.
 
My C-3826 gauge tester (ok a knockoff I made)
100 ohm potentiometer off Amazon, wires and alligator clips.
Some how somewhere I found the values.
High, Hot or full is 10 ohms
Mid range is 23 ohms
Low or empty is 74 ohms.
Works great with an adjustable power supply set at the proper gauge voltage.

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The fuel and temperature are fairly easy to test.

You'll need a good source of 5 volts. With some work, an old computer power supply can be used (google "convert computer power supply to bench power supply for directions) or rig something up with your new voltage limiter.

Then you need some resistors or you can spend a few bucks on a cheap Decade box like I did. More info here:
c-3826 tester for gauges and sensors

For the switches, the first thing to do is a simple continuity check with a multimeter. That will give you a good idea if they work at all, but the real test is when you put some current through them. I'd rig up an old headlight and a car battery or something like that and try the switch that way. To test it further, you can do a voltage drop test across the switch while you switch the headlight on.

Nobody ever watches this but I persist in posting it because it's good info about voltage drop.



The ammeter is a tougher one to bench test, although it can be done. Honestly, doing a bypass under the hood will take a lot of the current load off the power wiring under the dash and through the bulkhead disconnect. It will make the ammeter pretty much useless though. Here is a good explanation of the hows and whys. Some considerations about the charging and wiring upgrade and your worries about It's important to use a fusible link if you do that mod.
CBarge did a thread with better pics on the way it's done. Underhood Ammeter Bypass Read the Charger link first though.


Here's how I rebuilt, one wire at a time, the wiring harness in a '53 Chrysler. Just a piece of plywood and some finishing nails. I've been factories where they build wiring harnesses for high end military electronics and this is the same way they do it.

View attachment 386758


This is how we made our custom harnesses as well when i was in the harness building field.
Big plywood, troughs for laying the wiring into, and guides to lay the wire into as normal position as possible.
Final process was zip tying the harness once it was complete until it could be poly-cloth wrapped for installation.
A beautiful thing when done right.
 
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