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VDC and ABLS - What EXACTLY Are They?

9K views 36 replies 7 participants last post by  SmokeTitn3144 
#1 ·
I have a basic understanding of what VDC is and ABLS but what EXACTLY are they and how do they work?
 
#2 ·
TitanHauler said:
I have a basic understanding of what VDC is and ABLS but what EXACTLY are they and how do they work?
Let's see if I can explain this without the manual because it can be confusing too.

VDC - Vehicle Dynamic Control
ABLS - Active Brake Limited Slip

VDC is looking at yaw sensors, wheel slip, steering wheel angle, throttle position and I'm sure a few more that I'm forgetting. An example of what VDC can do will probably mean more than the technical description of it.

Here's what it's capable of:

You get into a corner too hot and find your about to lose control of the truck, well VDC is way ahead of you in this example because the yaw sensors and steering wheel angle sensor has already noted that your in trouble. It will back off the throttle and brake each wheel independently to regain the composure of the truck. Now of course it's not going to defy physics and get you out of trouble irregardless of what you try, but it is watching and waiting to act.

If you tow, VDC is a VERY MUCH worthy option to have. Especially if you get fishtailing, it will do all it can to straighten you out so the shiny side stays up... :D

Go into an empty (preferrably wet to save your tires) parking lot sometime where you can play a little, get the truck going 35 to 40 (to play it safe) and start trying to toss it around. That's the best way to get a feel for what VDC is capable of.

ABLS is another cool program. It will brake each wheel independently to help regain traction and it has the ability to back off the throttle as well if a slip condition is detected. There are limitations to the ABLS, one big one is it needs front tire rotation in order to brake a spinning wheel in the rear. So another words if your doing smokey burnouts with the brake on, you'll typically only get one wheel to spin, but as soon as you let off the brakes, the ABLS will detect front tire rotation and speed, it will then brake the spinning wheel so both hook up.

If all of this sounds too confusing I can post what the service manual says, heck it will probably do a better job than I just did. :(
 
#4 ·
Thanks Firecracker.... :D

There is certainly more going on that what I just wrote, I just tried to simplify it the best I could.

There's one more mysterious function that the Titan has, and it leads me to believe it will be a while before anyone (aftermarket tuners) is able to crack the code. It's called NTD (Nissan Torque Demand). There's only a small paragraph on it in the service manual describing it, but it's actually the mother of all the limiters. NTD will actually vary the torque output on the Endurance engine based on Altitude/atmospheric pressure. Nissan added this mysterious overseer to help the Titan perform better in higher altitudes, which means........we aren't getting all we could at lower altitudes because NTD is spoiling our fun......How's that for a huge bummer!!!
 
#5 ·
firecracker said:
8O JetTech............YOU ARE THE MAN!!! :D
Wow! I have to agree with Firecracker on that one! That was an outstanding explanation! It seems to me that the aftermarket tuner companies will have their work cut out for them. Do all Titans have ABLS? I know I have VDC (the button of course). What about NTD? All Titans have that I suppose. I tow a heavy trailer so I like that fact I have the VDC.

Am I right to assume that once aftermarket locking/limited slip rear differentials become available they may be useless in light of VDC and ABLS?
 
#6 ·
Do all Titans have ABLS?
Not all Titans have ABLS, if I remember correctly it's standard on the 4x4's and comes with the offroad/and or big tow package on the 4x2's.

I know I have VDC
Excellent choice on the VDC, you'll love it....

What about NTD?
The manual is so vague on NTD that it's really hard to tell much about it. I assume they all have it because it's more for altitudes then anything else.

Am I right to assume that once aftermarket locking/limited slip rear differentials become available they may be useless in light of VDC and ABLS?
I really don't know the answer to that one just yet. I believe Nissan confused things a lot when they offered the E-lock option but said it wasn't compatible with VDC. hmmmmm, that I doubt is really the case. It appears they had no intention of even using e-lock unless your in 4lo, at which time VDC shuts off too. So I'm a little skeptical on their explanation on that one. Also I don't see how a true LS diff would have a negative impact on the operation of VDC or ABLS. Heck in reality it would make ABLS work less....The true answer remains to be seen as to what the aftermarket offers for which options Nissan has used.
 
#7 ·
Let me say one more thing concerning NTD. Think about the possibilites this program has in it and the untapped potential. If this engine will make more hp to compensate for higher altitudes, then at lower atltitudes it means it's derated. In other words if an aftermarket tuner, such as hypertech or Jetchips can come up with a way to fool this sensor into thinking your at an extremely high altitude, then guess what???? Mucho more power with no additional mods. That's why I'm holding out for a program/tuner that will let us take advantage of the untapped potential this engine and ECU obviously has. Neat stuff ain't it??

Too bad I can't find anything in the service manual as far as the wiring goes to the NTD program, wouldn't an inline resistor be a nice mod... :D
 
#8 ·
so have you found any sensors under hood that you dont know what there for? nissan probably hid it somewhere.
 
#10 ·
now im going to go crazy knowing there is corked up power in the motor because of the damn ECU. almost wish i didnt read that part :lol: .....well mabye not.
 
#11 ·
jet tech, have you found the temp sensors that read outside temp to display to driver? i wonder if the altitude sensor is in that area?
 
#13 ·
im just tryin to think of spots where it might be. see i told you, im already goin crazy over this :D
 
#15 ·
well best wishes to your wife and good luck tomarrow. if the service manual has no mention of it in the wiring diagram its hidden. it could be anywhere on truck, mabye behind the dash somewhere not easily accesable.
what altitude are you at JT? my gps says im at 810 feet, im getting screwed to the max on this.
 
#17 ·
I'm starting to think the MAFS is somehow calculating the altitude and then sending it to the ECM because I just looked at every wire input into the ECM and not one made any reference to an altitude sensor. I'll have to do some reading on the net and see if the MAFS is able to do this.
 
#21 ·
i noticed that there are 5 or 6 wires into the MAFS, what else could be in there beside MAF and IAT sensors? that meens there are a couple extra wires in there. what are they for?
 
#22 ·
SMOKEDYA2 said:
i noticed that there are 5 or 6 wires into the MAFS, what else could be in there beside MAF and IAT sensors? that meens there are a couple extra wires in there. what are they for?
We have the 5 wire MAFS on our trucks. The MAF uses 3 of them and the IAT uses 2.

MAFS - 1 is power, 1 is ground, and the other is the signal wire going to the ECU.

IAT - 1 is for power and the other is ground.

I guess it's not there... :cry:
 
#23 ·
do you think this sensor might be right in the ECU? you said you couldnt find a wire lead for it :?
 
#24 ·
SMOKEDYA2 said:
do you think this sensor might be right in the ECU? you said you couldnt find a wire lead for it :?
I keep coming up with nothing on this topic of NTD. There is a picture in the manual that shows all the inputs to the NTD section of the ECU. Not one is in any way related to atmospheric pressure. I'm stumped. Maybe next week I'll stop in and see my Nissan tech buddy and see if he knows. I'll make sure to let you know what I find out.
 
#25 ·
cool thanks keep me posted
 
#26 ·
Thanks guys...this is a very enlightening and interesting post, I hope you pursue it. The aftermarket had a hard time cracking the ECU on the Hemi...and that's all they did. They didn't open it. Nissan's appears to be even more elaborate and complex.

Anyway, this dumb ol' country boy applauds your efforts...and your sharing :D . BTW BiXLL, watch the head, they're right! :wink:
 
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