CODE 15 (Open Coolant Sensor Circuit)
- Disconnect coolant sensor. See Fig 1
. With ignition on and engine stopped, check voltage between sensor connector terminals. Voltage should be greater than 4 volts. If voltage is less than 4 volts, go to step 3). If voltage is okay, check resistance of coolant sensor with engine warm.
- If resistance is greater than 1000 ohms, replace sensor. If resistance is less than 1000 ohms, sensor connection is poor or coolant is low.
- Check voltage from ECM terminals No. 17 to 22 with sensor disconnected. If voltage is less than 4 volts, ECM or connection is faulty. If voltage is greater than 4 volts, check for open in wire to ECM terminals No. 17 and 22.
Courtesy of GENERAL MOTORS CORP.