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Quick DBW question for swappers

K85 Octane

K85 Octane

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I've read somewhere that the DBW harness tends to be short, limiting where you can put the TAC module. Is this because the wiring from the pedal to the TAC is short...........or because the wiring from the TAC to the computer (or where ever it goes) is short?

Just looking to be ready. :waytogo: Thanks
 
If I remember correctly the wire from the pedal to tac box is on 12-18 inches,the wire from the motor is longer. I don't have my tac box permanently mounted yet but I think it will live on the firewall underneath the clutch master. Mine is an 04 5.3 not that it should matter.
 
I was just looking at that on mine. I can measure it out when I get home, but it does seem a little short.

That said, they're just wires. No reason you couldn't extend them if needed. right?
 
Right, but I've found a wrecked Tahoe and they guy is willing to sell me just the wires. So theoretically, I only have to cut one side instead of cutting and splicing TWO ends to make it longer.

They are tiny wires, not sure how I'm gunna do that. Maybe solder?

Ashman: you talking the pedal to TAC wires right?
 
I am, but depending on where I mount the TAC I might have to extend either side or both. On all of the wires I've lengthened so far I've been using solder and heat shrink. So far so good. :) It really helps to have a good soldering gun. I've seen them for as cheap as $15 and they beat the hell out of the old cheap irons.
 
K85 Octane said:
So theoretically, I only have to cut one side instead of cutting and splicing TWO ends to make it longer.
Click to expand...
Was just rereading that sentence and theoretically you shouldn't have to cut it at all. The wires feed through the firewall through a rubber grommet that should pull right out and the hole is big enough for the connector to come through with it. That is how mine is right now.

I'll take a pic for you as soon as I get home.
 
ashman said:
That said, they're just wires. No reason you couldn't extend them if needed. right?
Click to expand...

Maybe true in this application, I don't know. But you have to be careful this. Especially with sensors that measure resistance, as wire length or poor quality splices will add to the wire resistance.

O2 sensors would be an example of wires you aren't supposed to extend.
 
pics as promised:
Tac_wires1.jpg

This shows the TAC and the wires leading to the pedal. It's approx. 30" long. You can see the rubber grommet where it is supposed to feed through the firewall.

Tac_wires2.jpg

Here is the connection from the engine harness to the TAC. The white tape on the harness is approx. where the harness comes off of the engine between the 1 and 3 pistons. From there to the TAC is about 28-30".

Hope that helps.
 
Sorry Ashman, my brain has been all over the place with other stuff. Thanks for the measurements. When you installed yours, does the 28-30" of TAC harness reach to the firewall, to mount the TAC? Or did you mount it elsewhere?

Seems if it can be mounted on the firewall (driver side cause you said #1&3) than the pedal wires should be plenty long enough. Did you have to make a hole for that grommet or were you able to re-use an existing hole? I've been wondering if I can sneak things next to the steering column.

Lastly, about lengthening a wire that reads resistance.... I imagine if I HAD to lengthen one of the harnesses, it should probably be the TAC harness, since it's AFTER the chip that reads the pedal's resistance. Lengthening the wire between the TAC and pedal might cause resistance issues BEFORE whatever is inside the TAC that's reading it. If I made it long enough I could probably mount the TAC inside.
 
The pedal to tac is pretty short but you can buy longer harnesses if you are worried about cutting yours up http://secure.ultracart.com/catalog/PSI/ACCESSORIES/Pedals-TAC-Modules/HAR-1026.html

I added about 3 feet to my harness by splicing and the pedal still works fine. I had the TAC mounted to the firewall by the master cylinder for awhile but wanted to protect it a little better. I have it stashed above the parking break lever now.
 
I haven't decided where I'm going to mount the TAC just yet. I'm thinking on the firewall or drivers side wheel well/fender. I haven't tried to see if the wires reach to the firewall yet, but I'm not worried about lengthening the wires if I need to do so.

I think I'm going to have to make a hole. All of the existing holes are filled. I measured the grommet and I think it wants a 2-5/8" hole. I'm going to cut a hole in a piece of sheet metal and test it first though.

I think the firewall would be a great spot for it, but I have my hydraulic clutch master mounted there already and I'm running out of room. :(
 
Is it possible to sneak the wires along side the steering column? The large boot that goes around the column could be slit and the wires fed through. Or, before it's installed, run the harness between the boot and column, lets say underneath it for a concealed look, then install. I might end up doing that for my OBD2 extension from the engine harness to under the dash. My actual plug I believe will be under the hood but my gauges work off the OBD2 port, which means I need an extension to under the dash. Sneaking past the column sure beats drilling another hole for a big ass OBD2 plug. Hmmm could run it through the DBW grommet. Dunno yet

I wish I could check myself but I'm not at that point yet.
 
It's possible you could, likely I'd think but I don't know what the column hole looks like on a square body. I'm sure you could work something out though.

Hell, it's a good idea... maybe I'll steal it. :)
 
Oh, lol, gotcha.
I was busy with other stuff pretty much all weekend, but I'll take a look at it this evening and see if that looks possible.
 
Took a quick look, and it's totally doable. I may try that, or more likely repurpose the hole for the clutch rod. Since I switched to a hydraulic clutch that hole is unused on my truck.
 
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