If you have just installed some performance mods but your Jeep hasn’t responded yet, you may need to reset your ECU.By Jeffrey Smith – November 13, 2015

This article applies to the Jeep Wrangler JK (2007-Present).

So you have spent a small fortune on various performance modifications, but haven’t seen the results of your efforts yet? It is likely that your engine’s computer hasn’t yet adjusted to the new parts and is still trying to run with the existing OEM settings. This can be frustrating and really annoying. There is a simple fix for this. Your engine’s settings for such things as fuel to air ratios are automatically set at the factory for optimum stock performance. When you add new enhancements to such systems, the computer needs to make adjustments as well, and it sometimes needs a kick in the pants to get it in gear. Fortunately for you, this is a simple, no-special-tools-required procedure that will only take a matter of minutes to perform. Once you have performed this procedure, your Jeep may take up to about 50 warm-up periods (give or take) for the computer to learn the new optimum settings. The results of all your hard work should soon come to fruition.

Materials Needed

  • 8mm wrench to remove battery cables
  • Key

Step 1 – Remove the positive (red) battery cable

Use your wrench or ratchet to remove the positive battery cable. Only remove the positive cable. Leave the negative cable in tact.

Figure 1. Remove the positive (red) battery terminal only.

Step 2 – Ground the red cable to the negative terminal

Ground the positive battery cable to the negative battery terminal for about 30 seconds. Alternatively, you could also first disconnect the negative cable and move it well out of the way, then disconnect the positive cable and ground it to the metal frame for about 30 seconds as well. Either method should work.

Figure 2. Either ground the red to the black, or disconnect both and ground the red to a metal part of the frame.

Step 3 – Reconnect the positive battery cable

If you only disconnected the red cable and ground it to the black, reconnect the red cable now. If you used the alternative method, reconnect the positive first before reconnecting the negative cable.

Figure 3. Regardless of which method you use, always connect the positive cable first.

Step 4 – Turn on your Jeep

  • Insert your key into the ignition.
  • Turn the key to the “ON” position.
  • Do NOT start the engine.

Figure 4. Insert the key and turn it to the “ON” position only. Do not start your Jeep.

Step 5 – Cycle the headlights

With the key in the “ON” position, turn your headlights on and then off again.

Figure 5. Turn your headlights on and then off.

Step 6 – Turn the key off and remove

After you have cycled your headlights, turn the key off. The ECU has now been factory reset. It will take approximately 50 warm-up periods or driving cycles to re-learn the new optimal engine performance settings, and you should see all the modifications that you have made in full swing.

Figure 6. It will take up to 50 driving periods for the ECU to figure out the new performance settings.

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