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Thread: New fuse block and relay box installation

  1. #1
    Registered Member Custer55's Avatar
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    New fuse block and relay box installation

    Finally decided to install the fuse block I had built a couple of years ago before it gets to nice out. Once the weather takes a turn for the better I will want to be driving my 55 so I want to get this done now so It doesn't get put off another year.
    A couple of years ago I started looking at fuse blocks to replace the original one. I only needed the fuse block, not a complete wiring harness as I had replaced all the wiring with original style harnesses back in the mid 80's when I did the first frame off rebuild. I didn't find any that I liked so I eventually ended up building my own with the 4 circuit add on fuse blocks that can be hooked to each other. I already had one of this style added next to the original when I added my power seats, back up lights, radio and a cigarette lighter style power tap to my console.



    This is what I built compared to the original. I have it wired up so 4 circuits are always hot (1 - 4) 4 are hot in ignition switch position only (5 - 6) and 4 that are hot in accessory key position as well as the ignition position (9 - 12). The ignition and acc. circuits are powered through the relays at the top so there is less current going through the ignition switch. The green and red wires at the top are the trip wires for those relays.
    At the bottom is where the circuits will connect to the fuse block. I made that out of the male half of a dozen female/male quick disconnect terminals that have the plastic over them to make a sealed connection. I super glued the 12 together after crimping 12 gauge wires into them. The I used epoxy meant for plastics to fill in between the terminals to form a solid block which I then tie wrapped to the base just below the fuse blocks. Everything is mounted to a base plate. On the left side is a terminal strip to bring in power and grounds.



    Hard to get a decent picture under the dash but here it is mounted in place ready to re-hook up all the wiring. I have it mounted just to the right and just below where the original fuse block was. This makes it a bit easier to get to the fuses and hook up the wiring without being to close to the clutch pedal. Just to the left of the #4 fuse position you can just see a bolt I put in one of the original fuse block mounting holes to use as a ground stud.



    One thing I hadn't taken into account when I built the fuse block was a provision for the dash lights that are powered from the headlight dimmer switch. On the original fuse block five terminals in the upper left corner labeled ACC LP had 3 wires hooked to them. After some checking with my test light I figured out that one of the 3 was from the headlight switch dimmer control and the other 2 went out to the Dakota digital computer and the heater control panel lights. I was going to just add a buss bar type terminal strip but since I had an extra fuse block that I had room to clip onto the #1 - #4 fuse block I was the perfect solution. It just cleared my block for the incoming wires on the fuse panel so there wasn't room for the wires to come out the bottom of this one but that was easily solved by drilling a hole in the side to bring in the power connection from the headlight switch and the outputs to the lights. I only needed the 2 outputs for now so I left the fuses out of the unused ones. P.S. the terminals at the ends of the wires are the same type I used when I originally built the fuse panel. They are 1/4" male terminals and the female end they hook to have the same type of insulated covering so when you plug them together they are fully insulated.



    So with everything hooked up under the dash and checked to make sure it all works I stared work on installing the relay box that I purchased on Amazon. It has provisions for 6 relays and 6 fuse positions to feed power to the relays.
    It has a water proof seal on the cover and seals where all the wiring goes in from the bottom. On the left is the mounting plate I made from 1/4" aluminum to mount the box to and wire terminals for the input triggers, ground connections, relay power outputs and the single stud for the main power input. The brackets on the relay box came with it but I did re-bend them so it would mount more to my liking.



    Here is a shot of the box on the bracket. This side is where the relay trigger wires will hook up.



    Here is a shot of the box with the cover off ready to start wiring it up.



    Before I wired it up though I had to make brackets to mount it to the car. I decided on the passenger side by the core support as it was either this side or the drivers side. Since the power feed wires would be shorter on this side and my alternator is on the passenger side as well figured it would be as good a place as any. Some of the relay trigger wires will be longer this way but they are much smaller wires with way less current draw. The output wires from the relays go to both sides of the car anyway (headlights, horns and cooling fans) so it make no difference for those.



    Here is a shot of the brackets to bolt the whole thing into the car. The aluminum bracket on the left end will bolt into the filler panel and the 2 small brackets on the right will bolt into the inner fender. Those were a bit tricky to make as the relay box base and the inner fender were not at the same angles. In this view you can see the seals where the relay wiring goes.





  2. #2
    Registered Member Custer55's Avatar
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    Fuse block and relay box continued




    Here all the wiring of the relay box is done. The diagram on the left is how it is wired up. The bottom 3 relays are for a dual fan set with both at low speed or both at high speed as I will eventually need this set up when I get to installing my 95 Firebird engine and transmission I bought about 3 years ago. For now I just have a single aux. fan so I will be just using relay 1 for that. I did set it up with a ground trigger double pole/double through over ride switch though so that will be good to go when using the Firebird ecm to control the fans when I do that conversion. The top row of relays will be for the horn, low beam headlights and high beam headlights. The horn relay trigger coil is wired to the #4 fuse so it is always hot and will work just as original with the key off.



    And here is a view from the bottom with all the water proof seals in place. I used 12 gauge wire for all the power input and outputs and either 16 gauge or 14 gauge for the trigger coils to the terminal strips.
    Next will be getting the box permanently bolted in and doing some re-wiring to get everything hooked back up and working.

    So with the relay box wired up and mounted the project may be about halfway done.



    This picture is from a few years back when I re-located my battery to the trunk. One thing I had done on that project was the plate on the firewall to mount the starter solenoid. I never really liked the way that turned out so I decided to make a new one to replace it.




    This is what I mad to replace it. Also made from aluminum but painted semi-gloss black and shaped to follow the top of the firewall so it should blend in better. Eventually I paint it red to match the firewall, would have done that now but I don't have any matching paint right now. Also I got a couple of midi fuse holders that are stackable and a junction block stud to bring power off of the starter solenoid. The fuse holders and the junction block were not the same height so I just put a bend in the buss bar for the fuse holders to make it work.



    Here is a shot with the rubber covers on the fuse holders closed. I didn't have any button head 8-32 screws so I used the counter sunk ones I had to hold the fuse holders down for now.



    Here the plate is mounted to the firewall with the starter solenoid in place. Power to the fuse block and relay box will come off the top of the fuse holders which are fed from the starter solenoid to the junction block with a 4 gauge cable.



    And a shot from a bit further back, I replaced the cable to the starter motor as well with one that is the proper length.
    When I did my trunk mounted battery the one I ordered was too long so I had to put a loop in it which I never liked.
    In this shot also you can see how the wires to the passenger side mounted alternator come from the drivers side of the car. I am going to re-route these wires as well as they have been spliced multiple times over the years. When I did the first frame off build in the 80's I put in a new original style wiring harness with the original generator on the drivers side with external regulator. Over the years I then went to an externally regulated alternator and then an internally regulated alternator (which I am still using). Then that alternator was relocated to the passenger side when I did the C4 conversion frame and as I was really on a time crunch at the end of that build so I just did another quick splice job at that point. When I pulled the tape off the alternator harness on Saturday there was 3 splices in the 2 smaller wires and 1 in the main wire. Yikes!!



    So here is what I got done today. Since there will not be a horn relay on the drivers side anymore and the alternator wires will be re-routed with the rest of the wires at the top of the firewall I pulled all the tape off the old harnesses so only the wires I need will be in there. Basically just the low beam and high beam for the relay triggers, horn button wire, wire, park light wires and directional wires. At the core support the drivers side horn and headlight wires will need to go to the passenger side and to the relay output terminals. The cooling fan wires I am going to do in a separate harness as that will need to be reconfigured when I install dual fans.



    And lastly for today I have the power cable (8 gauge) run to the relay box and all the trigger wires hooked up. Turn signals and park lights hooked back up as they were originally (and working!!) I just had to move the connector up a bit to clear the relay box. I also have the new horn wires connected up and they work as well. All that's left to do is wire up the cooling fan, headlights, and re-routing the alternator wiring, and then get some nicer looking wire looms to cover up all the wiring. The weather is finally supposed to get nice up here by Wednesday so hopefully all that won't take too long.
    Brian

  3. #3
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    Really nice work on the fuse and relay panels Brian. It’s handy to have the front end fuses and relays close to their loads. Great job.

  4. #4
    Registered Member BamaNomad's Avatar
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    This task was like everything else that Brian has done... well planned and very neat!

  5. #5
    Registered Member Dragsix's Avatar
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    Man, that is sharp! Given any thought to using the ATO fuses that light up when they burn out?

  6. #6
    Registered Member Custer55's Avatar
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    Quote Originally Posted by TrifiveRichard View Post
    Really nice work on the fuse and relay panels Brian. It’s handy to have the front end fuses and relays close to their loads. Great job.
    Thanks Richard, will be a big improvement for sure having the newer style fuses instead of the old glass tube style.

    Quote Originally Posted by BamaNomad View Post
    This task was like everything else that Brian has done... well planned and very neat!
    Thanks Gary!!

    Quote Originally Posted by Dragsix View Post
    Man, that is sharp! Given any thought to using the ATO fuses that light up when they burn out?
    Thanks,
    I hadn't thought of using them, I will check it out.

  7. #7
    Registered Member Custer55's Avatar
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    Progress Update

    Pretty much finished up the project other than a few things that can be finished up later.
    Since the last post I got the alternator wiring re-routed to the passenger side. I had to make a splice in a couple of wires but it will be much better than it was before.




    Here I have all the wires re-routed using the junction block for power to the fuse block and relay box to join the original alternator charge wire to the new wires from the alternator. Just need to get some split loom over the wires yet to protect them from the engine heat.




    So the last part of the project was new headlight wiring to to the relay output terminals. The original headlight socket wires (below) were in pretty bad shape so the plan was to make new pigtails with new 14 gauge wires that will reach all the way to the relay box. Of course the sockets I had bought at a swap meet (top) were not the same style as the originals so some modifications were needed. First off I didn't have the original style headlight bucket seals so I used a grommet I had on hand for the buckets and added some smaller grommets with shrink tube over them to seal to the bigger grommet that will go in the headlight bucket. I think this will work fine as I rarely ever drive my car in the rain anyway.



    Here is a shot of the grommet that will go in the headlight bucket over the grommets and shrink tube on the wires.




    To make the new headlight sockets work the hole in the back of the bucket needed to be re-located to the center of the bucket instead of above center as original. Here I have the original hole all welded up and a new hole drilled in the center of the bucket.



    Next was to expand the bucket outward to gain a bit of clearance for the headlight socket. Here I have one clamped to a 1" thick block with a 3" hole below the bucket and a piece of 3/8" steel below that hole with a 5/8" threaded rod going through the whole thing. On the inside of the bucket I have a smaller round block to push the back of the bucket outward by tightening up nuts on the threaded rod. Again having a shop press would have made this easier to do.



    View from the top with the smaller block pushing the back of the bucket outward. This is a 2 " dia. block which ended up working good. I started with a 2.5" dia. block but could not get enough of a bump out with that one.



    This is the end result with the wiring harness and grommet in place plugged into the headlight so this is where it should all end up when installed back in the car. The wire harness will slide in and out of the grommet in the bucket so installing and removing headlights will work ok as long as I leave a bit of slack in the wire harness between the bucket and the inner fender panel.



    With a quick paint job on the buckets everything is ready to install with new halogen headlights. The new headlights should be much brighter as I still had an original T-3 on the drivers side with the low beam burnt out within the last couple of years and the passenger side being no newer than from 1976 when I bought the car.



    All wired up and ready to go. Some of the split loom I had left to finish up was bigger than needed so some of that will be replaced with a better size eventually but it looks ok for now and at least protects all the wiring. I wasn't sure how to properly aim the headlights so I just pulled up to the garage door and guessed at where they should be and took it for a ride just before dark Thursday night. Was pretty obvious they were to low and off the right so I googled how to do it the right way and I think I have them better now but won't know for sure until going for another ride after dark. Basically you need to pull right up to a wall and put cross hairs where the center of the headlights are and then back away 25 feet and then aim the lights so they are just below and to the right of the cross hairs. I took it for a longer ride last night and everything was working as it should. The readings on my voltmeter start out at about 14.6 volts and settle in at 14.3 to 14.2 volts which is a bit higher than it was before as it used to settle in the 13.5 volt range.
    So as long as no problems develop down the road I will call this project done.
    Brian

  8. #8
    Registered Member WagonCrazy's Avatar
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    Good progress here Brian. Drive it and enjoy it.
    1957 Nomad- LS1/T56 on C4 chassis
    1959 Fleetside Apache 1/2 ton, shortbed, big window, 327ci.

  9. #9
    Registered Member Custer55's Avatar
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    Quote Originally Posted by WagonCrazy View Post
    Good progress here Brian. Drive it and enjoy it.
    Thanks Paul, just got nice up here in Wisconsin so I will be driving as much as I can with our short driving season. Nice weather lasts until mid October if we're lucky.

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