'07-Present Wrangler's Control System - ESP OffPosted in How To: Electrical on May 1, 2009
When the all-new '07 Jeep Wrangler hit the streets, it had a lot of technology familiar to Jeep fans as well as a couple of new items. One of those new items is Electronic Stability Program (ESP) which was not only offered for the first time starting with the 2007 models, but was made standard. This doesn't give you just ESP, though. The program also includes Traction Control System (TCS), Electronic Roll Mitigation (ERM), Brake Assist System (BAS) and Anti-lock Brake System (ABS). See the sidebar "What is ESP and why does my Jeep have it?" for information on what ESP and the related functions are if you haven't heard of them.
Judging from internet discussions, a lot of JK owners could use a bit more factual information about these systems and how to turn some of them off if they really don't like them for off-roading or if they have installed larger tires and modified the suspension. We talked to three engineers who worked on the Wrangler, and on these electronic control systems to help explain what really happens when you start pushing buttons, and some tips to make disabling the system a little more science and less black-box magic.
In our experience, ESP works pretty well, and it often saves your skin on super-slippery surfaces so well that you don't even realize that you would be sliding without it intervening. These engineers knew, however, that TCS would not be good in every situation, and ESP would have a hard time functioning properly once the suspension was lifted and larger tires were installed. All of these systems can work well with these changes, but only if hours of skilled calibration work is completed to take into account the raised center of gravity and the increased unsprung weight of larger tires. So a few provisions were included in the programming that allows you to de-activate the ESP system. There are partial de-activation, temporary off and disable settings. The sequence to disable ESP isn't something you'll do by accident, or without practice for that matter, so we put together a short how-to that takes you through the needed steps.
The advantage of working with the system rather than just pulling the BAS fuse is that you can keep the ABS function even if you turn off everything else. And using the system allows you to turn off certain parts of it when you want for the best combination of electronic and driver control.
There's "Off" And Then There's "Really Off"The first acknowledgement that not everyone and not every situation calls for ESP comes in the ability to tone down the system. There are three ESP modes in 2H and 4H which you can select - Full On, Full Off, and Partial On - and two modes in 4L which the vehicle selects automatically and a disable feature. Full On is the way the vehicle comes from the factory, and it is active in 2H and 4H. It addresses any wheel slippage and is usually a good safety system without being too intrusive.
Some situations call for a little bit wheel slip, however, when you're trying to accelerate, which is when Partial On is handy. This de-activates the throttle control part of TCS when the transfer case is in 2H or 4H, allowing the tires to spin without electronic control. This is especially handy in soft sand and deep snow. To engage this Partial On setting, push the ESP Off button in the center stack. The ESP light (this is the icon of a car with squiggly lines under it in the center of the instrument panel) will come on and a chime will sound. To turn the system back on, press the ESP Off button again. The system will also turn back on when the key is turned off and then on again.
Full Off mode can be selected when the transfer case is in 4H. This shuts off all ESP and TCS features for speeds below 40 mph. To activate this mode, have the transfer case in 4H, the vehicle stopped and the engine running. Press and hold the ESP Off switch for five seconds. You'll hear a chime and the ESP light on the instrument panel will come on. If you drive over 40 mph, the system reverts to Partial On until the vehicle slows down to 35 mph. You can turn ESP and TCS back on by pushing the ESP Off button again or by keying the vehicle off and then back on.
In 4L, ESP and TCS automatically turn to Full Off. The only time ESP would switch on is if you drive over 40 mph. Once the vehicle slows to 35 mph it switches back to Full Off again.
And finally, the mode that is the most hidden and the one that most of you are interested in - Disable. This mode is designed to shut off ESP and ERM completely to avoid false activations that can occur with larger tires and a modified suspension. The system does not automatically reset, but can be turned back on by repeating the steps.
Going through the steps to reach the Disable mode is a lot like doing the Hokey Pokey, so you'll need to follow the photo sequence for step-by-step directions. It often takes four, five, or six attempts to successfully Disable the system. One final note; the 2007 model year (and early 2008 models) didn't have the Disable mode programmed into the computer. A Technical Service Bulletin has been issued by Chrysler LLC, allowing a dealership to reflash the computer and enable the Disable feature. If you own an '07 and want to disable the ESP, your first step is visiting the dealership.
As with most new systems, there is a lot to digest in the new Electronic Stability Program (ESP) and bundled technology. This is especially true for ESP on the 2007 through 2009 Jeep Wrangler, as it has functions and modes offered only on the Wrangler. Here's a quick guide that you can clip out and toss in your glove box.
|ESP Mode||Available When T-case is in:||Activate/Deactivate Mode||ESP Function||ERM Function||BAS and ABS Function||TCS Function|
|Full On||2H and 4H||Default setting; no need to do anything||Fully active||Fully active||Fully active||Fully active|
|Partial Off||2H and 4H||Press the ESP Off button once||Fully active||Fully active||Fully active||Traction control is off, but limited slip feature is still active|
|Full Off||2H and 4H||Press hold the ESP Off button for 5 seconds||Completely disabled below 40 mph||Completely disabled below 40 mph||Fully active||Traction control is off, but limited slip feature is still active|
|Full Off||4L||The system automatically switches when the transfer case is shifted in and out of 4L||Completely disabled below 40 mph||Completely disabled below 40 mph||Fully active, off-road ABS||Traction control is off, but limited slip feature is still active|
|Disable||2H, 4H and 4L||Do the Hokey Pokey as outlined in the photos and captions||Completely disabled||Completely disabled||Fully active, off-road ABS in 4L||Traction control is off, but limited slip feature is still active|
What Is ESP And Why Does My Jeep Have It?
Electronic Stability Program (ESP) is a chassis electrical system that monitors the direction your Jeep is going compared to what direction you want the vehicle to go, and then takes automatic actions to try to make the Jeep go the way you want. When a vehicle is sliding (oversteer or understeer), the system can decrease throttle and apply the brakes to one or more wheels to bring the vehicle back to the path that you are indicating with the steering wheel.
Oversteer is when the rear tires lose traction in a corner and the rear of the vehicle swings out. Understeer is when the front tires lose traction, not being able to turn the vehicle as quickly or as sharply as desired, and the front of the vehicle pushes forward instead of turning. The key components in the ESP system are a steering wheel sensor, yaw sensor, lateral acceleration sensor and automatic brake actuator that can apply pressure to the four brakes independently.
Electronic Roll Mitigation (ERM) is an extension of the ESP programming that anticipates a potential roll over caused by oversteer. It can't help in the slow type of roll over that happens on a trail caused by excessive side angle.
Traction Control System (TCS) does exactly what you expect it would - it applies the brakes and can decrease throttle to slow the tires if they are spinning when you are trying to accelerate. There is a limited slip feature built into this programming that will apply some braking to one tire if it is slipping more than the others. This redistributes the torque to the tires that are not slipping as much. This limited slip feature is active even when the rest of TCS is turned off (ESP is switched to Partial Off or Full Off modes).
And why would you want this automatic stuff on your Jeep? You might not, but the technology saves a lot of people who get into situations they can't drive out of. And no matter how good of a driver you are, you don't have the ability to apply one brake at a time, which is the advantage this technology gives the vehicle.