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Jeep JK Dash Warning Lights: What They Mean

Posted in Features on December 21, 2016
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Dash lights are one of the many joys of Wrangler ownership, and JKs are the most communicative Wrangler to date, but they can send you mixed signals. Of course, my disclaimer here is that your Jeep should see your local dealership as soon as possible if any indicator lights come on. It should be noted as to when any dash lights began and under what conditions. That said, we have developed our own protocol in the rental business for the various dash lights.

Not all wheel speed sensor wire problems are this obvious, but clearly, this one was causing the pretty light festival on the dashboard. When you modify your suspension, brake lines and wheel speed sensor wires must be long enough to allow for the extra wheel travel but carefully placed out of harms way when compressed.

ABS

For liability reasons, we ground rental Jeeps that have an ABS light on. Usually, this is a wire to a wheel sensor that has been damaged, not actual brake malfunction, so you can visually inspect at each wheel to see if a wire is rubbing. If you don’t have brake fluid leaking somewhere (you will know quickly, as your brakes will stop working), just know that your anti-lock brake and stability control system will likely be offline until you can get it fixed.

The ESC Off light is the bottom left. It will be on normally when you are in 4L. The top right ESC light (also known as the “snakes chasing Jeep” or “bacon road” light) will flash when the ESC system is activated, but it will be solid when the ESC system has malfunctioned.
Another indicator light that will likely illuminate when you have a faulty wheel speed sensor wire is the hill descent control, as well as the ESC OFF message. Different model-year JKs have the HDC light in different places on the dash board, and very early JKs used ESP (electronic stability program), not ESC (electronic stability control).

ESC light (ESP/BAS on older JKs)

This is the “snakes chasing Jeep” light, not the “ESC Off” light, which will normally be on when you are in 4L. Though the electronic stability control will not be operational if that light is on, it is not necessary to park the Jeep immediately, unless the malfunction is causing the braking system to activate constantly while driving the Jeep normally. Usually you either have a bad clock spring or you hit something and bent or knocked your frontend out of alignment. These are the steps we take. First, check tire pressure—all four tires should be within 2-3 psi of each other. Second, check steering wheel—is the steering wheel straight when driving the Jeep straight or is the steering wheel cock-eyed? Adjust drag link as necessary (and get a professional alignment as soon as convenient, and see what else you may have damaged in the process). Third, if you have performed the above, the steering wheel is straight, and the light is still on after driving for 3 or more miles, the Jeep usually requires a clock-spring sensor replacement.

Sway Bar

The sway bar light may be flashing because it was not disengaged correctly or because there is a malfunction in the unit itself. Visually inspect the unit for damage. Did the front cross member hit the wiring harness? Is there mud or water visible at or above the unit? Is a mount or sway bar link broken? Next, disconnect the battery to reset the unit. If you do all of that and the light is still flashing, it will require a full or partial new sway bar power unit. If you aren’t going to do that soon, disconnect the ponytail wiring harness at the sway bar motor and secure it behind the grille to avoid further irritation to the CAN bus. Some of our early JKs would die altogether with a bad sway bar still connected.

Axle Lock, Front or Rear (“Lockers”)

Not necessary to park the Jeep, unless locker will not disengage, which is characterized by a distinct tire chirping and hopping while trying to turn on pavement, even in 2WD. Park and turn off Jeep. Restart and reassess. A locker that will not disengage warrants a tow truck once you get to maintained roads.

Though the ABS light (top) is usually caused by a damaged wire or wheel speed sensor, it still means that your stability control and ABS may not function. The airbag light (bottom) is not related to the ABS light. The airbag light is most commonly a malfunctioned clock-spring sensor. Those two systems are not interrelated.

Airbag

If the airbag light is going on and off (and dinging annoyingly every time), dust has chewed up the clock-spring sensor in the steering wheel. If the light is solid, it could be the clock-spring or a bonafide airbag malfunction. Typically, if the airbag light is on, the airbags are not going to deploy unexpectedly, but rather, they won’t deploy at all, even if you need them.

Though a solid engine light is usually not a dire issue, it should be dealt with at your earliest convenience. If it is flashing, do not ignore it. Stop driving as soon as it is safe to do so and call a tow truck.

Engine

If you have owned any car manufactured since the early ’80s, then you have seen this light and probably been conditioned to ignore it. However, a flashing engine light is extremely bad. Park the Jeep immediately and call a tow truck to take it to the dealer. It means the engine is sensing a misfire and there could be dire consequences if you continue driving. A solid engine light can be a myriad of sensor issues, and we consider it OK to drive for a while unless it is running “funny.”

So, in summary, a flashing engine light is bad, but a solid engine light is OK. A flashing ESC light is OK, but a solid ESC light is bad. An ESC Off light is normal. An HDC light is normal, unless you are not in 4L and the ESC Off light is also on. Clear as mud?
Relationship counseling not included.

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