Unplug the cooktop. Flip up its hinged top until it holds in place with the provided support rod or rods.
Unscrew the bracket holding the ceramic igniter, which sits equidistant between the exposed burners and may resemble a tiny spark plug. Cut the wire leading to the igniter near its base.
Overlap the end of the new igniter wire to the clipped end of the old wire and wrap the overlap tightly with electrical tape.
Pull the cooktop out from the wall.
Unscrew the top back panel from the cooktop and set it aside. Locate the control module, typically an orange or blue plastic box on the upper right edge of the cooktop back. Tug gently on its incoming wires and observe which one makes the taped new wire move out of the upper compartment.
Pull the old wire to guide the new wire to the control module. Wiggle the old wire’s connector off its post and press the replacement wire’s connector onto the module.
Test the burner. Replace the upper panel. Press the support rods away from the front of the cooktop slightly, lower its top and push the cooktop back into place.