How to Change the ECM on a Chevrolet HHRby Zyon Silket
The electronic control module (ECM) on the Chevy HHR is the brains of the vehicle. Without it, the engine would not know how to run properly. When the ECM goes bad, you must replace it with a new or reconditioned ECM. The relatively straightforward process for removing the ECM requires the use of basic tools. Even novices can change the ECM on their HHR.
Remove the screws that hold the passenger side kick panel against the right side of the inner fender under the dashboard using a Phillips screwdriver. Pull the panel off the fender.
Unplug the three wiring harnesses from the ECM --- a silver box with three ports located on its side. Three individual wiring harnesses plug into the ports. (The ECM is the only silver box behind the panel.)
Remove the four bolts that hold the ECM onto the fender using a socket and ratchet.
Place the new ECM onto the inner fender, and secure it using the four bolts and socket.
Plug the three harnesses into the ECM. Each harness has a different shape to ensure you plug it into the correct port.
Place the kick panel over the ECM, and secure it using the screws and screwdriver.