mjkjmk1

I`m trying to find the coolant temp. sensor on my 89 Cherokee 4.0. NOT the temp. sending unit or the temp. switch, but the coolant temp. sensor. Any help would be appreciated.

5-90

As you've probably already figured, you have three.

1) The sensor that drives the IP gage/lamp is at the driver's side rear of the cylinder head. Takes a 7/16" wrench (as I recall,) and threaded 1/8" NPT. Be careful with this one - it's easy to twist the head off!

2) The switch for the electric fan is in the radiator tank, on the driver's side. Takes a wrench somewhere around an inch - I don't recall exactly.

3) The sensor for the ECU (the one you sound like you're looking for) is down on the driver's side of the engine block, kinda behind the exhaust manifold. When you look down there, you'll see two sensors - the lower one should have a plug like on your fuel injectors, and you should see a foil overwrap on the wiring if you pull back the cover a bit. This is not the CTS - it's the knock sensor. You can leave that one alone. Look up on the block about 4" above and probably 6" behind the knock sensor, and you should see the coolant temperature sensor.

NB: Pulling this one will lose most of the coolant in your system. I'd advise you to do a radiator flush before you pull the sensor, since you'll have to change coolant anyhow. Flush, rinse, change sensor (letting all of the water drain out,) and refill with coolant mix.

Cherokee 4.0

well explained