Total re-design: questions and updates on new chassis wiring.

[A-man930]

I've started designing a new chassis wiring harness for my truck; partially in preparation for a tdi swap and partially because I've grown to really like wiring and electrical systems and just want it all fresh.

I see there's a green fusible link feeding power to the switch and there's two outputs that feed the "run" position (one also feeds the "acc" position.)
By counting the fuse ratings on the circuits fed by these two I come up with 32 amps on the "run only" output and almost 90 amps on the "run and acc" circuit!
Am I crazy or is that really high?!
The next question would be are these two portions of the switch rated to carry different amounts...
I believe this is all GM stuff btw.

[Jeep Driver]

There is a thread here regarding the Renix system (which does not apply to you) and the volt meter showing a load when the blower motor is on. What no one is paying attention to is the load the blower motor is drawing. The way the Renix meter is wired it's reading the load at the fuse block and not the output at the alt/battery as it should be.

The point is- from a practical matter and not a scientific one-

The 90 amp link you are referring to, the load is not near 90 amps, otherwise you'd burn the link every time you applied a full load, ran all acc at once, a full load may be closer to 50 amps. No, I doubt the switch is designed to carry a different load in separate parts of the switch, the different links apply to two different circuit requirements.

 

If it were me and I was to design a new harness, or modify the existing one-

I'd find a relay bank from another vehicle or an aftermarket one, I'd run all high load appliances through the relay bank-

Head lights

Aux lights

AC

Efan

Head unit with AMP

Blower motor

Etc....

 

Before the relay bank I'd install two BREAKERS, one for ignition and one for acc or non essentials. 100amp and maybe a 40 amp......that you'd have to work out but I'd definitely get rid of the links.

 

I'd pay no attention to the ignition switch itself other than maybe replacing it.

[gogmorgo]

Look at the wires going to it. 14 AWG, if memory serves. Depending on your data's source, your max current will be 30 amps or so.

If you're ever in doubt of an electrical component, just run a relay. It's really not worth setting your truck on fire.

[A-man930]

The current plan is to use a bussed fuse/relay center in the engine bay to handle most of the higher current loads as you're suggesting.

 

I'm wanting to utilize the ignition switch itself (fused of course) to carry the smaller loads in the cab and the turn signals and whatnot. I just want to have an idea of the switch's safe limits.

 

And yes my truck currently has a Renix 4L but I don't plan to integrate this new harness with the Renix system. Hopefully there will be a VW diesel controller in there ;)

[A-man930]

Here's the box I think I'm gonna use for the underhood center.

The fuse slots (20 on each side) are both bussed to studs on the underside. The 10 relay locations along the center are the newer iso 280 type (which is pretty cool really; all 2.8mm spacing for fuses, relays, flashers, breakers, etc.)

[ftpiercecracker1]

Thats a pretty sweet piece. Do you have a link/price? How beefy are the studs for the incoming ground/hot leads?

[HOrnbrod]

Ever consider using a 91-95 XJ/MJ Power Distribution Center (PDC)?

 

[A-man930]

Thats a pretty sweet piece. Do you have a link/price? How beefy are the studs for the incoming ground/hot leads?

http://www.waytekwire.com/item/46354/RFRM-FUSE-RELAY-2-88-MM-DUAL/

[A-man930]

Ever consider using a 91-95 XJ/MJ Power Distribution Center (PDC)?

The only reason I'd consider one is the provision for the MAXI fuses.  Otherwise I'm pretty well sold on the newer style 2.8mm stuff.  It would be cheaper!

[neohic]

Ever consider using a 91-95 XJ/MJ Power Distribution Center (PDC)?

 

I'd go this route. Kabowabo used one with his Renix refresh a while back in HIS THREAD.

 

 

[A-man930]

Well there's been no official progress made, but there has been much brainstorming, planning, researching, and drawing.  This is a heavily edited Mitchell schematic for the truck's lighting circuits.  It's not done yet (get 30min here and there to work on it,) but I figured I could get some other eyes looking at it and get a critique or two as I continue.

 

 

 

 

 

The lighted rear view mirror should be from a 90s Lumina. 

 

[A-man930]

Mkay, I'm thinking about revamping the turn signal and hazard functions.  

 

This is an EP28 3 terminal flasher.  

 

[A-man930]

Again, no physical progress yet, but I'm just about settled on this setup for the lighting circuits. I still need to assign wire colors (I'd like to not have multiple same-color wires in close proximity to each other during the install and for later troubleshooting purposes  :D)  I'm attempting to utilize all factory switches and have the add-on items be readily available "off any parts store shelf" items.  

 

Here's the big changes so far:

-Fog lamps will be enabled with the parking lights and will continue to work during high or low beam operation.  

 

-A front-mounted LED lightbar can be linked to the high beam circuit or operated independently by a dash-mounted switch.  

 

-The flasher is an ISO280-base EP28 unit (un-tested here guys, hope to mock this up soon.)

 

-The lamps marked "amb lts" are ambient "mood lights" if you will; probably red LEDs.  Call me ricer, but I had them under the dash on my highschool beater and I loved them.  I also like some of these newer cars that put a recessed LED in the overhead console or rearview mirror to barely illuminate the shifter/console area.  So I'll try it!

 

-The biggest change is with the turn signals.  I'll put an amber LED bulb in place of the rev. lamps in the factory tail lenses and add an outside marker LED to the bumper (whenever it's done  :shake:)  As designed here, this marker and the factory "vertical" amber lenses on the grille will be illuminated any time the key is in "run" and will wig-wag opposite its corresponding lamp when the turn signal switch pulses power to the right or left turn relay.  I may add a "marker-cut" switch to allow an all-dark mode eventually.  

 

Give me some feedback fellas!  Any more features I should think about?  What do you wish was different about the lights in your MJ?   :popcorn: 

[A-man930]

I'm reconsidering the fog light operation... maybe it'll be totally divorced from the headlamps.

[Eagle]

-Fog lamps will be enabled with the parking lights and will continue to work during high or low beam operation.

Not legal.

 

Federal regulations require that fog lights MUST NOT operate when the headlights are on high beam.

[A-man930]

 

-Fog lamps will be enabled with the parking lights and will continue to work during high or low beam operation.

Not legal.

 

Federal regulations require that fog lights MUST NOT operate when the headlights are on high beam.

 

 

I've often wondered that.  I'm not so certain its much of a legit safety concern so long as they're aimed properly; and I'm also not convinced It would ever be noticed.  When it comes to vehicles, I'm all about the driver having control over the machine's functions.  

[Tanner]

I guess this thread died huh? It's too bad I was really looking forward to how this turned out. A project I will likely be undertaking in the future

[A-man930]

The project is not dead.  Turns out I'm going to get a practice run on it in a buddy's rig first.  I'll post up some pictures of it as we start to make progress

[Tanner]

Cool I'll be watching out for it!

[A-man930]

The biggest hold-up to starting the project has been how physically integrated the engine control is with the rest of the truck's harness.  I'd have to move and re-wire a bunch of the Renix stuff to get it to drive again... all of that work on an engine management system I plan on doing away with isn't really where I want to spend my time.  

Enter an old high school buddy wanting to swap an LS into his old IH truck that needs totally re-wired anyways.  Perfect  :chillin:

[Tanner]

touche, good stuff bro

[A-man930]

Wanted to give an update for y'all.  

Progress is moving fast on my trial run (buddy's Travellall).  I'm more and more happy with the fuse block we selected; it looks to be the perfect blend of versatility, space, cleanliness, and simplicity.  

 

Versatility: There is a vinyl overlay covering up an additional row of "terminal spots" next to the outboard fuse locations.  Cutting away a section of the overlay allows a fuse or an ultra-micro relay to be installed without being on the buss bar (this is aside from the center 10 spots dedicated to relays).  This pretty well does away with any feeling like being handcuffed to constant B+ from the buss bars on either side; its easy to install an unbussed fuse or relay (see the two ultra-micro relays in the top right of the 1st pic).  

 

Space: It isn't nearly as big and bulky as it looks.  

 

Cleanliness:  The fact that it is bussed on either/both sides should make for a much cleaner install than individual power wires running to any fuse or relay that needs power.

 

Simplicity:  All 3 types of relays shown in the second picture along with any mini fuse (ATM) fit into the same sealed Metri-Pack 280 terminal.  

 

 

 

 

 

Left to right: "high amp", micro, and ultra-micro ISO 280 base relays and an ATM "mini" fuse

[HOrnbrod]

Still no physical progress?

[Tanner]

I like what I'm seeing  :thumbsup:

I recently picked a power dist center from a 95 to slap in mine for a few extra relay/fuse spots and clean it up a bit. 

but I like the versatility of the unit you picked up.

So I may be reconsidering my plan.

keep the updates coming

[Megadan]

You have my interest.    I like the idea of mini fuses and micro relays as well as the bussed power like you.   I could assemble a basic setup outside of the truck and tag everything to install at a later date.

I suck at reading wiring schematics, but it looks like you built in a headlight relay harness into the system to take the main load off of the headlight switch.  

This is a smaller fuse block similar to what you have, but same basic design.  Think this would handle enough to run basic chassis duty?  Maybe a pair of them, one under hood, the other under dash? http://www.delcity.net/store/Sealed-Mini-Fuse-&-ISO-280-Mini-Relay-Combo-Panel-!-Individual-Inputs/p_803803.h_803804.t_1.r_IF1003?mkwid=skXzRAiBp&crid=38094426869&mp_kw=&mp_mt=&gclid=CN7iwd_FjswCFYSAaQod6UoJcw