Replaced Temperature Sending Unit--Won't Start.

[GMDiesel]

The temperature gauge didn't work, replaced sensor. Cleaned engine with a degreaser and rinsed off. Replaced coolant reservoir and refilled with coolant. Engine cranks and will not start. Check gauges light comes on. Plugged in block heater to get engine warm, still no start condition. What to check?

Up date, replaced unit on passenger side front, reinstalled old unit and it now statrts. AutoZone replacement did not work. I now understand this sensor is for the ECM? I changed it because the temperature gauge does not work, but this is the wrong sensor for that?

[john8662]

Yeah, leave that sensor alone.

The sender you're looking for is located on the Driver's side of the engine near the front on the cylinder head (behind alternator), this drives the gauge inside.

J