4low-trac

The only reason I say that is because the yellow wire being cut on this mod versus what I did, is that the signal is interrupted for the 4WD system and not the traction control ecu. Thus, tricking the computer to think that the truck is not in 4LO, will not use the 4LO shift patterns. And I still think that the blinking 4LO indicates a problem.

 

It seems like loads of people are happy with the current yellow wire mod. If you have a way to improve on what is a popular mod then thank you for your contribution to the community. I looked over the directions in your previous post and found them confusing. Is there any way you can simplify the write up for what you did to help my- simply cut the yellow wire- type mind.

 

Amigo, TRAC OFF is NOT the traction control off. As you say in your video and is the source of so much confusion here. It is TRAC OFF MODE, which is TRAC with the engine regulation turned off. It should be called TRAC MAX. In other words, a stronger limited slip to get unstuck as the engine is not regulated (throttle cut). AUTO LSD is the 2WD version of TRAC OFF.
ONLY VSC OFF MODE turns TRAC and TRAC OFF MODE off.

What I don't understand is why your VSC button does anything at all in L4. In L4, the VSC is off automatically. The button cannot switch TRAC on or off in L4, since TRAC and VSC are disabled in L4. This needs further research!

 

The VCS button is able to function in L4 because the traction control ECU is enabled as it would be in H4. That being said I can turn on or off the function, like the video shows.

 

What did you do to enable something that doesn't exist for others here (that's why the yellow wire mod). Or, have you done the Yellow Wire Mod and that explains it all?

 

The mod is also called the yellow wire mod, except I interrupted the signal for traction control ecu. This is the third plug on the same column, cut wire#9. The wire from ecu pig tail gets blocked off and the input wire is supplied with a 12v signal. Because under normal conditions the ecu emits that 12v signal so you are just simulating that.

 

so what this does is stop the blinking "4lo" right and nothing else?

 

No, it tricks the traction control ECU rather than 4WD system. Because tricking the 4WD system in H4, does not signal the transmission computer to use the L4 gear shifting when in L4.

 

Very interesting. Have you tested the mod out in offroad conditions to show it works?

 

Question: In 4LO everythign is turned off, and open Diff's. Correct?
So the e-brake poor mans locker trick doesn't really do anything since TRAC and all that is turned off, Correct? Maybe in 4HI or 2WD, Correct?

so the YWM turns TRAC on with out engine regulation on for all 4 wheels?

 

No, it does indeed so something, because everything else is off, your manual brake application can help. If the electronic brake/ traction control worked, then you wouldn't need to use your parking brake to control slipping.

 

Completed the same mod, here is a video with techstream. Pay attention to the trac/vsc off mode in the techstream display view. Seems to work as advertised, but haven't tested it offroad yet.

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Interesting and visual video showing that in L4 (which has no TRAC or TRAC OFF) with the yellow wire mod acts like it in in H4 so that TRAC and TRAC OFF both work. That's what the yellow wire (4-Lo Trac) mod is supposed to do!
This is a Godsend for all 4x4 Tacomas that are not Off Road TRDs!

 

I noticed your 4 low wasn't flashing. Did you ground the relay?

 

This is a different mod than the normal yellow wire mod that most are doing, but seems to achieve a cleaner solution.

From a page back in the thread that jp_flynavy posted, believe the original idea came from this thread(https://www.yotatech.com/f117/4l-trac-done-right-280412/):

"Note: On "Instrument Panel Junction Box No.2", behind the glove box, the six plugs are labelled sequentially as PA on the top (as mounted), through PF on the bottom.

Pins are numbered. As mounted, there are two vertical rows of pins, start counting pin numbers from 1 at the BOTTOM RIGHT pin, follow the row to the top, then continue from the BOTTOM LEFT and up.

9-PC is a yellow wire with a black trace.

If you clip that wire, you are, indeed, blocking the low range signal from reaching the skid control ECU, however, this will cause the skid control warning light to go on, and all electronic brake control functions to fail. The problem is that the 4WD ECU outputs a low current +12v on the low range INPUT pin. This is basically a signal to the skid control ECU that it is actually in HIGH range. When the sensor on the transfer case is activated, it provides a zero-resistance to 0v chassis, so it pulls the +12v down to 0v. The skid control ECU expects the +12.

Solution: tie that wire via 100 ohm resistor to +12. You can probably omit the resistor, but it is a cleaner solution to limit the current going in to a low current sensor.

To make it switchable, use an SPDT switch with the wire clipped off of 9-PC connected to the switch's common pin, +12v/resistor to either of the other two pins, and 9-PC to the last. Flip the switch one way and it is "normal", flip it the other way, and it is TRAC-LO. No warnings, no errors.

Note: for those with automatic transmissions, the low range signal is also sent to the ECM for altering transmission shift patterns. Doing the old yellow-wire mod will NOT inform the ECM that the transmission is in low, which means that it will be using a high-range shift pattern. This 4L-TRAC mod will MAINTAIN the low signal to the ECM, which will allow it to shift correctly for low range."

 

Do you have any pictures of the plug or pinout of the wire?

 

See attached, yellow wire with black trace, snip from connector then run tap into a 12 v source and run to that wire. There are screenshots of which wire that feeds 12v in previous posts.

 

Thanks, I got which yellow wire it is, the +12 threw me off. +12volt source is the answer. Finished this up on @HrBrad8 truck. Only hit on small bump when I turned the key on to roll down the window with the PC connector unplugged. A quick round of Techstream had the codes (Trac off+check engine lights) cleared. @DFANNEY6 I think you need to update your yellow wire mod I did on the trail.

 

I just want to add a little extra clarity to this method.

Here's a full image of the PA-PF connector showing PC connector


A close up of PC connector showing pin 9


A Wiring diagram showing the interactions with 4wd and PC connector


A closeup of the mod cut the wire going to PC-9 and tap the wire side to +12v Ign keyed power.

 

Thanks!!