got a 2004 zr2 blazer can someone tell me where the coolant temp sensor is located? gotta get the old one switched out.

 

Driver side cylinder head between cylinders 3 & 5 on the side of the head.

 

The sensor for the dash gauge is in the driver side cylinder head as Kyle mentioned. The engine coolant temperature sensor, (ECT) for the OBDII is next to the thermostat housing.

 

it has threads on it right? and screws into the block?

 

2004 == only one sensor, not separate sensors. That happened in '99 if I remember correctly which is when the BCM took over controlling the dash and talked with the PCM for its information instead of pulling directly from sending units & sensors. My '00 Bravada only had the one, two-wire sensor in the driver side head and just a blank, un-machined boss on the lower intake manifold where the 96-98 ETC sensor went.

The location for all 99+ is in the driver side cylinder head threaded into the head. The hole that it threads into opens up into the coolant passage in the cylinder head so expect to loose some coolant in the process. Have the new sensor ready to put in right away to minimize the lost coolant.

 

Good call on the single sensor and class II communications! (I missed the 2004)

 

Just to clear up auto parts jargon, the sensor for the computer is the temperature sensor, the sensor for the gauge is the temperature switch. That will ensure you get the right thing when you ask the kid behind the counter. As for the later model single sensor... I dunno.. Temperature Sensor Switch?

 

Doesn't really matter what they call it, there's only one. So as long as the kid behind the counter can look it up, you should get the right part