ECM/ECU location

Good morning,

I attached the location of the ECM for you.

Why are you replacing it? Do you have any codes? Was it confirmed as a failure?

Roy

REMOVAL

Use the DRB scan tool to reprogram the new power-train control module (PCM) with the vehicles original identification number (VIN) and the vehicles original mileage. If this step is not done, a diagnostic trouble code (DTC) may be set.

Fig.11 PCM Location
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The PCM is located in the engine compartment next to the air cleaner assembly.

To avoid possible voltage spike damage to the PCM, ignition key must be OFF, and negative battery cable must be disconnected before unplugging PCM connectors.

1. Disconnect negative battery cable at battery.

Fig.12 PCM Mounting
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2. Remove cover over electrical connectors. Cover snaps onto PCM.
3. Carefully unplug the three 32-way connectors from PCM.
4. Remove three PCM mounting bolts and remove PCM from vehicle.

INSTALLATION

Use the DRB scan tool to reprogram the new power-train control module (PCM) with the vehicles original identification number (VIN) and the vehicles original mileage. If this step is not done, a diagnostic trouble code (DTC) may be set.

1. Install PCM and mounting bolts to vehicle.
2. Tighten bolts to 4 Nm (35 in. Lbs.).
3. Check pin connectors in the PCM and the three 32-way connectors for corrosion or damage. Also, the pin heights in connectors should all be same. Repair as necessary before installing connectors.
4. Install three 32-way connectors.
5. Install cover over electrical connectors. Cover snaps onto PCM.
6. Install battery cable.
7. Use the DRB scan tool to reprogram new PCM with vehicles original Identification Number (VIN) and original vehicle mileage.

As indicated in the pictures that Roy attached it is in the left front of the engine bay. The unit is the Power-train Control Module. It controls the engine, transmission, emissions and some electrical parts of your Jeep. That is why it goes to PCM when you look for it. An ECU is typically an engine controls only part.
They are not a drop in part and need to be programmed to allow it to control the various items.