Install of VSC cancel switch - Page 10

slalomkayaker · 02-05-2007, 05:40 PM

I think this mod could be alot easier if we find a way to trick the computer into thinking it is in 4LL.

No error codes, only a switch to be activated...hmm if someone with more electrical experience could help that would be great.

Thanks!!

31moppie · 02-05-2007, 06:18 PM

Grounding out the white/blue and the grey wire does exactly that. Unfortunately, as soon as the rear wheels spin and the front ones don't, it sets off an error code. That dumb computer is smarter than we think. Say, is that an oxymoron??? If only my highschool english teacher could see me now.lol

**bugs1961** · 02-06-2007, 02:01 AM

Quote:

slalomkayaker previously said:

I think this mod could be alot easier if we find a way to trick the computer into thinking it is in 4LL.

No error codes, only a switch to be activated...hmm if someone with more electrical experience could help that would be great.

Thanks!!

I think I have found a way to put in a switch that will fool the skid ctl ecu into thinking the truck is in 4wd low. Unfortunately, I'm out of town until Sunday and can't test this so maybe one of you will give it a try.

In order to fool the ecu and not generate any error codes, I think both the EX1 and EXl4 will need to be grounded. This is how the thing works: when you put the truck into 4hi (HL)--EX1 is gounded; and when you shift into 4lo (LL)--EXl4 is grounded. See page 190 of the electrical diagrams.

One switch will ground both wires if a DPDT switch is used. I found a switch at RadioShack.com that would work: RadioShack.com - Cables, Parts & Connectors: Component parts: Switches: DPDT Heavy-Duty Rocker Switch It's part number 275-691. See the drawing I made of the back of the switch with the terminals represented by the short lines inside the box.

Also looking at p190 of the wiring diagram, you can see that both the grey EX1 wire and the white/blue EXl4 wire go to the same connector called EA2. This connector is located on the left kick panel. See p51 of the wiring diagrams and the picture shows where the EA2 connector is located, although it's hard to see exact detail. You would have to look and find the connector and locate the two wires. Using this connector would allow easy switch wiring since the two wires are together. By disconnecting the skid control connector, you can use an Ohm meter or continuity tester to determine which end of the cut EX1 and EXl4 wires go to the ecu. These are the ends that need to be attached to the center terminals of the switch.

You would want to cut the two wires and connect a length of new wire to each end of each wire to run up to your switch. There would be four wires going to the switch. Looking at the left half of my drawing, you can see the four wires coming to and from the switch. Grey for EX1 and light blue for EXl4. Remember you're viewing the switch from the rear and looking at the six spades sticking out of the back of the switch.

The right half of the drawing shows the ground circuit that would be active when the switch is set to VSC/TRAC off. Power will be coming in from the skid control ecu to the center terminals and going to ground through the right side terminals. Splice the two ground wires together and attach to any grounded bolt under the dash. In this position, the skid control ecu will get the normal 4wd low signals and should turn on the "VSC OFF" light and the "squiggly skid symbol" light. Yippie, VSC and TRAC are off!!

When the switch is in the left position (in my drawing) the EX1 and EXl4 circuits would be connected just like they were before the mod and everything would be normal. VSC and TRAC are on.

Make sure you use a switch that has just two positions and not one that has an on-off-on or you'll set codes for an open in the circuits when in the center position. I'm just putting this out there if someone wants to give it a try.

Good luck,
Bugs

31moppie · 02-06-2007, 07:58 AM

This is what I have been trying to do all along. See post #70. The EA2 connector is where I have been doing all of my cutting and splicing too. Just follow the wires from the plugs ends to find which ones go to the SkidControl ECU. They are the ones that go into the harness that goes thru the firewall. The only thing different from what you suggest is that I spliced into each circuit and then grounded them from there. Maybe cutting the wires and just grounding the ones that go to the ECU will give a better result. A great switch to use for anything you want is a marine rocker switch made by Blue Seas. They come in many different configurations, are cheap ($10.00), and fit the factory cutouts with just a little trimming deep inside the hole (a small angle die grinder works great).

**bugs1961** · 02-06-2007, 10:15 AM

Quote:

31moppie previously said:

This is what I have been trying to do all along. See post #70. The EA2 connector is where I have been doing all of my cutting and splicing too. Just follow the wires from the plugs ends to find which ones go to the SkidControl ECU. They are the ones that go into the harness that goes thru the firewall. The only thing different from what you suggest is that I spliced into each circuit and then grounded them from there. Maybe cutting the wires and just grounding the ones that go to the ECU will give a better result. A great switch to use for anything you want is a marine rocker switch made by Blue Seas. They come in many different configurations, are cheap ($10.00), and fit the factory cutouts with just a little trimming deep inside the hole (a small angle die grinder works great).

31Moppie,
Bummer. I reread post 70 and think you should try grounding the two wires to the skid control ECU and see what happens--might work. If not, here is another idea. How about grounding the grey and the blue/white wires at junction connectors B45, pin 9 for the grey wire and B46, pin 9 for the white/blue wire. Those pins are where the wires go to the ADD or center diff lock switch and transfer L4 switch and are located behind the glove box, to the left of the ECM. See pp 196, 197, and 45 in the wiring diagram. This would send the "4wd low" signal to the engine ECM also so it would believe you are in 4low and now maybe not turn on the check engine light. Every system that normally receives the signals would receive them. I would still want to switch them as I described above if it works.

I would guess that the wires need to be grounded as that is how they are when you go into 4wd low. Splicing the wires without cutting them may give a confusing signal to the ECUs. You could achieve the same result as cutting by taking the pins out of the connector and grounding them with alligator clips to test the mod. If it doesn't work, just plug them back in and you're done.

I'll check out the switches you mentioned--sounds great.

Thanks for your efforts and willingness to try things,
Bugs

31moppie · 02-06-2007, 05:02 PM

It is sometimes hard to tell that that the grey wire and the white/blue wire are all interconnected (within their own colors) It depends which schematic you use. Ground the grey wire anywhere in the dircuit and all of the ECU's connected to it are grounded too. I think the problem arises in the SkidControl ECU. It has no problem thinking that everything is in 4 LO until you spin the rear wheels. It knows the back ones are spinning but can't figure out why the front ones arn't and so it sends a trouble code to the Engine ECM. There is a wire (pink and some other color I think, I don't have my schematics with me) that tells the ECU that the vehicle is a 2WD if it is grounded out. I tried that but then none of the 4WD functions operate and so you can't fool it into thinking that you are in 4WD and disable anything. There is yet another wire for the 2WD vehicles that disables the LSD. I tried it too but you still get some kind of traction control. I'm not sure but I'm thinking it's kind of like ATRAC and TRAC for the 2WD models. Perhaps someone with a 2WD model can confirm this. Still thinking about it, although I don't think there's much left to play around with.

**bugs1961** · 02-06-2007, 05:28 PM

Yea, you may be right. Right now I have a switch on the grey wire and it is working well enough, with the limitations mentioned earlier. Better than nothing, I guess. Keep us posted if you find out anything more.
Bugs

slalomkayaker · 02-06-2007, 05:56 PM

Hmm...maybe we could put a switch on the speed sensor to the center differential or something to that nature...

I guess if we can't figure it out through hardware, someone should look into reprogramming the ECU

hurricane · 02-07-2007, 11:38 AM

good post on all the mods. i love it

kathleen · 02-13-2007, 07:04 PM

this thread is great .. thanks bugs for directing us kids lost in all the other crazy threads on this topic... you boys are a becon of hope for the people that dont have time to figure it out on their own.. THANK YOU!

Kat.