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Looking for an Ignition switched positive wire preferably under hood.
Only to be used to switch a relay, no load to speak of, is there somewhere easy to tap into?
2004 Australian truck, based on 2002, (pre digital dash)
I have some wiring diagrams but I am unsure which ones apply to my truck.
the bottom fuse in the Adapter is the OEM 10A fuse,
the top fuse location, is for your accessory.
you do NOT want to try and tap into the fuse panel from the back side, I looked, a night-mare
I used it to turn on my 340A MechMan alternator, which can't be controlled thru the OEM wiring,
because some shade tree guy hacked up the alternator wiring harness to install a Leese-Nevel alternator which bit the dirt, because it got packed full of the insulation from the hood
On the lower part of the dash is 1 connector with nothing plugged into it. I was told it was a connector that activated high idle if needed on a commercial vehicle like an ambulance. It has 1 switched 12v lead which is what I tapped into. I could not put the cover back on the fuse panel with a tap a fuse so I didn't go that route. Couldn't find anything else under the dash or under the hood without disturbing the harness.
Most of this generation of super duty trucks I have seen , has a pass through harness for installing accessories, on US market , it is to the left side of the steering wheel , top of firewall near the brake master cylinder .
it is a series of wires , with shrink wrap like caps on them .
it is inline with the fuse box .
maybe yours has it also , except on the right side
Most of this generation of super duty trucks I have seen , has a pass through harness for installing accessories, on US market , it is to the left side of the steering wheel , top of firewall near the brake master cylinder .
it is a series of wires , with shrink wrap like caps on them .
it is inline with the fuse box .
maybe yours has it also , except on the right side
I will have a look on Friday, if it is there, I can do some clean-up of the wiring on accessories fitted before I got the truck, it was messy, I am working through it.
The battery terminals are my next bug bear, mangled by years of abuse, I want to replace with good heavy cable and military terminals, just need some time.
I will have a look on Friday, if it is there, I can do some clean-up of the wiring on accessories fitted before I got the truck, it was messy, I am working through it.
The battery terminals are my next bug bear, mangled by years of abuse, I want to replace with good heavy cable and military terminals, just need some time.
like I did here?
when you get new terminals on, apply FLUID FILM to all connections that tend to corrode.
these batteries are 2 plus years old, and no corrosion, period.
I spray FLUID FILM on everything that tends to corrode, especially ground connections,
Emergency brake lines and steel cables.
Last edited by John in OkieLand; May 27, 2026 at 04:18 AM.
Most of this generation of super duty trucks I have seen , has a pass through harness for installing accessories, on US market , it is to the left side of the steering wheel , top of firewall near the brake master cylinder .
it is a series of wires , with shrink wrap like caps on them .
it is inline with the fuse box .
maybe yours has it also , except on the right side
My truck has them, but they aren't hooked to anything on either side of the firewall so no power to tap into there.
If you want something already under the hood, it sounds like cleatus has got you covered.
Originally Posted by cleatus12r
Vacuum pump light blue/pink tracer.
If you’re not wanting to splice into a utilized circuit in the factory harness, I used the empty high idle connector harness that’s behind the 4 pinned panel same as Eman.
Originally Posted by Eman85
On the lower part of the dash is 1 connector with nothing plugged into it. I was told it was a connector that activated high idle if needed on a commercial vehicle like an ambulance. It has 1 switched 12v lead which is what I tapped into. I could not put the cover back on the fuse panel with a tap a fuse so I didn't go that route. Couldn't find anything else under the dash or under the hood without disturbing the harness.
Then you can use one of the “customer access” pass through wires ashleyroachclip was talking about to get it under the hood. We can only assume they’re on your right side as ours are on the left.
Originally Posted by ashleyroachclip;
Most of this generation of super duty trucks I have seen , has a pass through harness for installing accessories, on US market , it is to the left side of the steering wheel , top of firewall near the brake master cylinder .
it is a series of wires , with shrink wrap like caps on them .
it is inline with the fuse box .
maybe yours has it also , except on the right side
On the lower part of the dash is 1 connector with nothing plugged into it. I was told it was a connector that activated high idle if needed on a commercial vehicle like an ambulance. It has 1 switched 12v lead which is what I tapped into. I could not put the cover back on the fuse panel with a tap a fuse so I didn't go that route. Couldn't find anything else under the dash or under the hood without disturbing the harness.
bro, could you take a couple of photos of the clip and location? would much appreciate this.
Then you can use one of the “customer access” pass through wires ashleyroachclip was talking about to get it under the hood. We can only assume they’re on your right side as ours are on the left.
The paas through wires are there and on the Left (USA drivers side) but the ones inside the cab are well hidden.
I soldered a wire into the Vac pump power, and it works perfectly, it was
to trigger a relay for DRL in my headlights and driving lights.
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