VSC / TRAC defeating - is anyone closer?
01-19-2005, 05:13 PM
#122
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Hi guys.
I'm happy to see this issue being worked again. I was looking at this about two years ago and posted several of the electrical diagrams on Webshots (as rjm681) that mikNTx showed above. I exchanged a few emails with Hillbilly (Scott) and we tried a few things, but in the end I couldn't make much progress. Then the snow melted, and I sort of gave up.
Here were my thoughts and what I tried.
a. I believe the same part number ECU is used for both the 4WD and 2WD (which has the TRAC OFF switch.)
b. I believe the ECU has software/firmware inside it. If Toyota does configuration management like we do where I work, if a piece of hardware (ECU) has software/firmware in it, different versions of firmware result in different part numbers. In this case, 2WD or 4WD would have a different part number.
c. Given this, since the part numbers are the same, my thought was that the firmware for the VSC/TRAC ECU is the same, and that the addition of a switch would take effectively turn the "TRAC" off as it would on the 2WD.
I was wrong. Or at least not 100% right.
Here is what I did.
d. As mikNtx shows in V18, Pin 26
in my 2002, this pin was empty. If you look at the electrical diagrams scanned on page 148, and 149 here:http://community.webshots.com/album/67333305UapMuK,
You'll see that the 2WD TracOff switch goes to ground off of V18, pin 26.
e. In many electrical systems a floating pin is considered "on" and a grounded pin is "off". My thought was that if I were to ground Pin 26 manually, then I would serve the same purpose as the switch.
f. I went to Radio Shack, bought some butt connectors (64-3073) that would slide on the pin through the connector, attached a lead to it and slipped it on pin 26. I grounded the other end.
g. I had light snow on my uphill driveway and I tried it out. I also tried it on a gravel road with light snow.
h. I don't think it had any effect. I tried to spin the wheels and noticed that the throttle cut off a little and I heard ABS chatter. Of course, I didn't really recreate the situations that I've been in when I've had it happen to me before... namely trying to cross a snow covered intersection with a semi approaching on the cross street, and he has the right-of-way. It's under those conditions that the Traction Control always seems to help me...
i. The good thing is that I didn't let any of the smoke out of the ECU and once I removed the "mod" everything is working as well as it did before. As a word of caution, if you try this, I can't promise that you won't let any smoke out...
j. Where to go from here. I would be nice if someone were to check what I said above, and if they agree, try to ground V18, pin 26 and see what their results are. Also, if my belief is true that different firmware has a different part number for the ECU, the it is possible that there is another pin that the ECU reads to tell it that it is a 4WD ECU rather than a 2WD ECU. If this is the case, I think a "fix" may get more complicated.
Let us know...
Bob
I'm happy to see this issue being worked again. I was looking at this about two years ago and posted several of the electrical diagrams on Webshots (as rjm681) that mikNTx showed above. I exchanged a few emails with Hillbilly (Scott) and we tried a few things, but in the end I couldn't make much progress. Then the snow melted, and I sort of gave up.
Here were my thoughts and what I tried.
a. I believe the same part number ECU is used for both the 4WD and 2WD (which has the TRAC OFF switch.)
b. I believe the ECU has software/firmware inside it. If Toyota does configuration management like we do where I work, if a piece of hardware (ECU) has software/firmware in it, different versions of firmware result in different part numbers. In this case, 2WD or 4WD would have a different part number.
c. Given this, since the part numbers are the same, my thought was that the firmware for the VSC/TRAC ECU is the same, and that the addition of a switch would take effectively turn the "TRAC" off as it would on the 2WD.
I was wrong. Or at least not 100% right.
Here is what I did.
d. As mikNtx shows in V18, Pin 26
in my 2002, this pin was empty. If you look at the electrical diagrams scanned on page 148, and 149 here:http://community.webshots.com/album/67333305UapMuK,
You'll see that the 2WD TracOff switch goes to ground off of V18, pin 26.
e. In many electrical systems a floating pin is considered "on" and a grounded pin is "off". My thought was that if I were to ground Pin 26 manually, then I would serve the same purpose as the switch.
f. I went to Radio Shack, bought some butt connectors (64-3073) that would slide on the pin through the connector, attached a lead to it and slipped it on pin 26. I grounded the other end.
g. I had light snow on my uphill driveway and I tried it out. I also tried it on a gravel road with light snow.
h. I don't think it had any effect. I tried to spin the wheels and noticed that the throttle cut off a little and I heard ABS chatter. Of course, I didn't really recreate the situations that I've been in when I've had it happen to me before... namely trying to cross a snow covered intersection with a semi approaching on the cross street, and he has the right-of-way. It's under those conditions that the Traction Control always seems to help me...
i. The good thing is that I didn't let any of the smoke out of the ECU and once I removed the "mod" everything is working as well as it did before. As a word of caution, if you try this, I can't promise that you won't let any smoke out...
j. Where to go from here. I would be nice if someone were to check what I said above, and if they agree, try to ground V18, pin 26 and see what their results are. Also, if my belief is true that different firmware has a different part number for the ECU, the it is possible that there is another pin that the ECU reads to tell it that it is a 4WD ECU rather than a 2WD ECU. If this is the case, I think a "fix" may get more complicated.
Let us know...
Bob
Last edited by emplusten; 01-19-2005 at 06:11 PM.
01-19-2005, 05:37 PM
#123
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Originally Posted by emplusten
..............
the it is possible that there is another pin that the ECU reads to tell it that it is a 4WD ECU rather than a 2WD ECU. ..............
the it is possible that there is another pin that the ECU reads to tell it that it is a 4WD ECU rather than a 2WD ECU. ..............
pin 24 (pink-green)? ref p.148
Last edited by mikNtx; 01-19-2005 at 05:39 PM.
01-19-2005, 06:07 PM
#124
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Originally Posted by mikNtx
pin 24 (pink-green)? ref p.148
IND2= Indicator #2??
CD= ???
If you look on page 158 of the 2002 electrical manual which describes the 4WD, you'll see that pin 20 of F7 (4WD ECU) goes to the 4wd lamp. If this line is also the sensor to say "I'm a 4wd ECU" to the V18 VSC ECU on pin 24, then the experiment I tried when I was in 4WD may work if you put the truck in 2WD. We'll have to give that a shot.
01-19-2005, 06:49 PM
#125
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Bob,
That's awesome info. Thank you for bringing it back to the surface. I also know this subject has been discussed time and again, but the situation I was in that prompted me to start this thread was the 'final straw'. If Toyota's electronic wizardry can be deciphered, allowing us to install a factory "TRAC OFF" switch, I'll be the first (or second) at the local dealer gladly plopping down some money for the right switch....
Andreas
That's awesome info. Thank you for bringing it back to the surface. I also know this subject has been discussed time and again, but the situation I was in that prompted me to start this thread was the 'final straw'. If Toyota's electronic wizardry can be deciphered, allowing us to install a factory "TRAC OFF" switch, I'll be the first (or second) at the local dealer gladly plopping down some money for the right switch....
Andreas
01-21-2005, 07:11 PM
#126
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Hey guys,
I'm anxiously awaiting for you to solve the VSC/Trac problem. Seems weird that in 4wd (ok, AWD), that the 4runner spends so much energy trying to keep you from going. Maybe its my tires (Dunlops), but it seems like i can't touch the gas in a parking lot without the ABS going nuts.
Not to hijack this thread...maybe I should repost this, but it seems related: how long does it take 4H to engage on your runners? I have an '02 (3.4L Auto, stock) and it seems like it takes ~30seconds and probably 50yards of driving before it clicks in. My old '95 would switch over instantly, and its bothering me.
Also, when shifting from 4H to 4L (while in neutral), it grinds. The grinding is similar to not depressing a clutch fully when shifting a manual, or not putting it fully into gear and then letting the clutch out. Is this normal?
I'm anxiously awaiting for you to solve the VSC/Trac problem. Seems weird that in 4wd (ok, AWD), that the 4runner spends so much energy trying to keep you from going. Maybe its my tires (Dunlops), but it seems like i can't touch the gas in a parking lot without the ABS going nuts.
Not to hijack this thread...maybe I should repost this, but it seems related: how long does it take 4H to engage on your runners? I have an '02 (3.4L Auto, stock) and it seems like it takes ~30seconds and probably 50yards of driving before it clicks in. My old '95 would switch over instantly, and its bothering me.
Also, when shifting from 4H to 4L (while in neutral), it grinds. The grinding is similar to not depressing a clutch fully when shifting a manual, or not putting it fully into gear and then letting the clutch out. Is this normal?
01-22-2005, 05:55 AM
#127
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Jordan,
The delay while going from 2WD to 4WD is very normal. There really is no specific time for this, as a few conditions have to be perfect in order for the front driveline to get engaged. From what I've read and heard, the front diff has a pneumatically-actuated splined collar that slides into place when you click the 4WD button. Depending on how the splines are matching up, your forward speed, and whether or not there is pressure on the driveline - will all affect how quickly the front is engaged. The easiest way I have found is to slip the tranny into Neutral right before I depress the 4WD button. That takes tension off of the driveline and allows the transition to happen fairly quickly. If you are sitting still and try to engage 4WD, it may not work, as something typically needs to give in order for the mechanism to work. So think of a splined collar trying to slip onto a splined shaft the next time it takes a while. Try my Neutral move and it should help.
As for the grinding sound when going from 4H to 4L - it happened to me also in the beginning. After posting on here about the problem, I was told to make the shift as quick and as solid as possible. In other words, don't slowly try to move the stick between H and L. Also, if your transfer case fluid is warmed up, you'll find the shift to be slightly easier. Make sure you are fully stopped and then try it as I stated - a firm, quick shift between the two positions.
Hoped that helped!
Andreas
The delay while going from 2WD to 4WD is very normal. There really is no specific time for this, as a few conditions have to be perfect in order for the front driveline to get engaged. From what I've read and heard, the front diff has a pneumatically-actuated splined collar that slides into place when you click the 4WD button. Depending on how the splines are matching up, your forward speed, and whether or not there is pressure on the driveline - will all affect how quickly the front is engaged. The easiest way I have found is to slip the tranny into Neutral right before I depress the 4WD button. That takes tension off of the driveline and allows the transition to happen fairly quickly. If you are sitting still and try to engage 4WD, it may not work, as something typically needs to give in order for the mechanism to work. So think of a splined collar trying to slip onto a splined shaft the next time it takes a while. Try my Neutral move and it should help.
As for the grinding sound when going from 4H to 4L - it happened to me also in the beginning. After posting on here about the problem, I was told to make the shift as quick and as solid as possible. In other words, don't slowly try to move the stick between H and L. Also, if your transfer case fluid is warmed up, you'll find the shift to be slightly easier. Make sure you are fully stopped and then try it as I stated - a firm, quick shift between the two positions.
Hoped that helped!
Andreas
Last edited by aowRS; 01-22-2005 at 06:01 AM.
01-22-2005, 05:59 AM
#128
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Thread Starter
For Ducky
An incentive:
To Ducky, or anyone else who figures out the electronic wizardry behind Toyota's wiring, and solves this mystery, I will personally purchase and ship the correct Toyota TRAC switch as a heartfelt thanks!
I'm not looking for a ghetto solution that requires a bunch of cutting, splicing, etc. Just a safe, and stable method of switching this headache on and off.
Andreas
im just not looking forward to the 60-70$ switch
I'm not looking for a ghetto solution that requires a bunch of cutting, splicing, etc. Just a safe, and stable method of switching this headache on and off.
Andreas
01-22-2005, 06:59 AM
#129
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It snowed about 10 inches last night and we are expecting another 6 today. My 4-Runner is great except for guess what. So in order to help this process along, and since I am a electronic moron, I would be willing to help fund a member (Ducky?) in his research. I would think the $$$ could be used for parts, switches, wire, and a post mod write up.
Got a paypal account?
Any one else, or is this a really bad idea.
Got a paypal account?
Any one else, or is this a really bad idea.
01-22-2005, 11:03 AM
#131
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A knowledgeable and rogue Toyota technician that's willing to part with the knowledge sure would be handy. I asked at my dealer, but they're too scared to pony up any information.
01-26-2005, 10:37 AM
#133
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Freedom!!!
Well, sort of. I checked my factory service manual again this morning and decided to unplug the "Oil Pressure Sensor Connector" at the master cylinder. This is the forward facing of the various plugs (see pic below - sorry for the huge size). What I found is that the "VSC OFF", VSC TRAC", and "ABS" indicators are then illuminated. More importantly, I could sling slushy snow all over the neighboring county. 2WD, 4WD - didn't matter. The 4Runner finally behaved like a normal 4WD version would. I think I had more fun in the first 5 minutes then I'd had in the almost four years of ownership. I also found that I could re-connect the plug at any time and the indicator lights would go out again. In other words, the truck did not have to be restarted in order to clear the lights. At one point, I pulled out onto a road and left somewhere around $17 worth of premium REVO rubber behind - man that felt good!
The connector in question has three wires. I do not have the service manual version with the wiring schematics, so someone else will need to chime in and identify these three mystery wires. I see no reason why one could not find the appropriate wire of the three, and graft an on/off switch in-line. Ideally, the Toyota TRAC OFF switch would accomplish this, but frankly any clean rocker switch similar to the fog light switch would work. There is a blank under the fog light switch begging to be filled with this switch...
I hope that helps somewhat. At this point, if I knew the function of each of the three wires, I would move forward and try my switch thought.
It just felt so nice to punch it and have huge amounts of snow fly all over the place - without a hint of the usual electronic symphony!
Andreas
The connector in question has three wires. I do not have the service manual version with the wiring schematics, so someone else will need to chime in and identify these three mystery wires. I see no reason why one could not find the appropriate wire of the three, and graft an on/off switch in-line. Ideally, the Toyota TRAC OFF switch would accomplish this, but frankly any clean rocker switch similar to the fog light switch would work. There is a blank under the fog light switch begging to be filled with this switch...
I hope that helps somewhat. At this point, if I knew the function of each of the three wires, I would move forward and try my switch thought.
It just felt so nice to punch it and have huge amounts of snow fly all over the place - without a hint of the usual electronic symphony!
Andreas
Last edited by aowRS; 01-26-2005 at 10:41 AM.
01-26-2005, 10:48 AM
#134
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wow im so jealous!
all you did was unplug the wire pictured and it worked?? and then when you went to plug it back in it went back to normal??
good work!!
all you did was unplug the wire pictured and it worked?? and then when you went to plug it back in it went back to normal??
good work!!
Last edited by lee; 01-26-2005 at 10:49 AM.
01-26-2005, 10:53 AM
#135
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Lee,
That's all I did. Hence my thought that we could tie in at this point and be done with it. As long as someone is able to identify the three wires first.
Go out there and give it a try!
Andreas
That's all I did. Hence my thought that we could tie in at this point and be done with it. As long as someone is able to identify the three wires first.
Go out there and give it a try!
Andreas
01-26-2005, 12:56 PM
#138
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Simon,
That would indeed be beautiful. I don't think we'll be that lucky though. I thought someone had Vol. I of the service manual that includes the wiring schematics? I only have Vol. II.
Andreas
That would indeed be beautiful. I don't think we'll be that lucky though. I thought someone had Vol. I of the service manual that includes the wiring schematics? I only have Vol. II.
Andreas
01-26-2005, 01:13 PM
#139
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Hey if you look at page 146 of the wiring diagram it shows the master cylinder and 3 wire going to it, black red and white...they all go right in to the VSC ECU
