Ground Circuits
- Turn ignition off. Using ohmmeter connected to ground, backprobe each ECM ground terminal. For ECM ground terminal identification, see appropriate pin voltage chart in PIN VOLTAGE CHARTS article. Resistance should be zero ohms. If resistance is not close to zero ohms, repair open to ground.
- Start engine. Using voltmeter connected to ground, backprobe each ground terminal. Voltage should be less than one volt. If voltage is greater than one volt, check for open, corrosion, or loose connection on ground lead.