Doyon

Last night at the drag races I had a horrible time making sure my T/C was off. Everytime you start the car it would be on and you'd have to push the button to turn it off, and having to turn my car on and off a bunch made me confused on if i turned it off or if i'll be turning it on. Anyways, while I was sitting there I was thinking, well why don't I disconnect the button from the wire its connected to. Then I thought, no that will only prevent me from turning T/C off.

Has anyone else disconnected their T/C? If so, how did you do it?

Thanks,

Josh

cliffyk

On the '99 to '04 models the t/c switch is a momentary contact unit that sends a pulse to the instrument cluster, which then sends a digital command via the SCP (OBD2) bus to the ABS module to toggle the t/c off or on--so with the switch disconnected there would be no way to send that pule to the cluster (and on to the ABS module)--I.e. no way to turn it off after starting the car.

The PCM tells the ABS module (also over the SCP bus) whether the t/c is enable or disabled. This can be changed in the tune, however it permanently disable the t/c--pressing the button does nothing.

There was someone making a digital device that could be set to turn it up at start-up, I think it was $70, then went up to $80, then went away as that was kind of pricey when all you have to do is press the button 'til the green LED is on = t/c off.

This outfit claims they have "a few in stock" for $53.

I have no use for it here in Florida so it's just turned off in the tune. If I get ambitious I'm yanking out the whole ABS system...

wayne613

My ignorance of the 99-04's is vast, but I think it's doing much the same as the newer models via the cluster...

$50 for one of these seems a bit extreme for something that is likely quite simple. This guy, and a couple others did it with a simple 555 timer circuit, but it can probably be done far simpler, assuming he's ok with it not working right in odd-ball situations like when it doesn't start on the first try cranking.

From cliffyk's previous follow-up posting on a similar thread:


Assuming I'm reading that right, you would just need to hook up a 12v "hot in start" fuse tap from the CJB using a relay to the Gray (or black with light blue stripe if I'm wrong) wire coming off the TCS control. Splicing into it, or using a wire-tap. Assuming the CJB has a hot in start fuse and the logic uses 12v, you can skip the relay as it would be redundant...

Should be easy enough to verify with a multi-meter. Verifying that 12v is the signaling logic being used when pressing the button with IGN on, on that Gray line. This will then just simulate you pressing the button down as you crank the engine, and will default it to off for you.

Doyon

Thanks Cliff, but as my luck, it is no longer available (said it at the top of the product)

Doyon

Thanks for the links and diagram. I think I may buy another switch and solder the point A and B together (Seems like the easiest haha) as said in one of the links, that way I can just pop that in at the track and leave the normal one in for my daily driving.

Thanks to both of you for giving me some great ideas!

cliffyk

I don't know what points you are referring to as A and B, however be aware that you can damage the instrument cluster by connecting the wrong terminals. The '96 to '98 models can be modified with a simple switch or relay , as can apparently the later models; more than one owner has toasted their instrument cluster by attempting to do this with a '99 to '04 MY car.

I.e. it won't work, same as holding the switch while starting the car does nothing--that's why people could get away with charging $60 to $80 (there was one over $100) for a device to do it. I designed a circuit to do it, if I can find it I will post same, however there's no way I could have sold it for less than $75 and made a penny.

Also unless it's plug 'n play most people will not be interested and the factory connectors (if you could find them) would easily cost $50 a set in small quantities (500 to 1000 sets).

wayne613

Yeah, I'd really verify what's going on. I got jack of knowledge for the older models, other than what catches my fancy. Electronics has been a life-long hobby(career for a bit), but I don't have the experience, or the schematics. It would be a lot easier if you guys had the online wiring schematic cheat sheets hosted like we have.

I assume from cliffyk's description the 99-04's ABS module is on a delay, and/or needs to be a closed circuit for more than a second, hence the need for a 555 timer IC. Just wiring the two points together even if you verified those are the ones that close when you push the button isn't a good idea.

The link I gave still sells them for $50, not cheap, but unless you are a bit confident of your ability to verify any and all of this with a DMM and test it out before you really do anything, likely you may wish to just spend the money as the knowledgeable person in this section suggests.

cliffyk

The t/c button raises the instrument cluster input high (+12V, battery voltage via fuse 2.5)) when pressed AND when the key is in the RUN position--ONLY in RUN, not in any other position. When it has been released, the cluster's microcontroller senses the falling voltage at the the t/c switch input and sends an OBD2 message to the ABS module telling it the switch was pressed AND released.

The ABS module then examines the current state (on or off) of the t/c and changes (toggles) it to the "other" state, when this is done it acknowledges the request and reports to the cluster (via an OBD2 message) the current t/c state. The cluster controller then turns the LED t/c state LED on or off as needed.

Because just pressing the button, without releasing it too, tells the cluster nothing--jumpering the switch leads will do nothing.

The circuit I created used a dual 555 timer with both timers operating in monostable mode. One to create a delay of a a couple seconds after the engine was started and the key returned to run, and then after the delay the second timer produced a 250ms or so pulse used to switch a transistor in parallel with the switch--I.e. mimicking a human presseing and releasing the switch.

It's a simple circuit, if I can't find the schematic I'll created a new one when I get a chance...

wayne613

So just needs a 556, supply transistor, couple resistors and caps, or do bi-stable, yes? Either way, I'm interested.

Doyon

Very interesting info, especially about the failing cluster, I sure don't want that haha. I already thought of somthing else, maybe a little bit easier (for me anyways). My problem is that my traction control button is right next to my shifter in the shift bezel. I normally don't pay attention to that part of the car, and the light is very dim for the T/C button especially in the day time. I plan to be restoring my interior to dark charcoal and I thought maybe i'll hook up a small LED light off to the side of my dash (cleanly of course) where I can clearly see if my T/C is on or not.

Cliff, if/when you do make that schematic, i'd be very interested in looking at it.

Once again, thanks you very much guys!

Josh