temp light test 1996 cherokee 4.0L

I bought a used 1996 jeep Cherokee with the low end gauge cluster (no temperature gauge – just a red light that should light up if it overheats). The light does not light up when turning the key before starting when the other lights do (oil pressure light lights up). Is this normal or has it been disconnected or broken. Is there a way to test it to see if it is working?

Thanks for any advise or help with this.

Besides pulling the instrument cluster and putting in a new bulb, I've tested a couple by pulling out the coolant temp sensor, turning on the key, and holding a lighter to the sensor for a bit while a buddy watches for the light.

That's an idea! but brings up the next question for me of where is the coolant temp sensor located?



Besides pulling the instrument cluster and putting in a new bulb, I've tested a couple by pulling out the coolant temp sensor, turning on the key, and holding a lighter to the sensor for a bit while a buddy watches for the light.

Mounted on the top of the water pump. Looks to be in either the upper radiator hose neck, or the heater core outlet neck..

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Great diagram thanks! What is the difference between the temperature sending unit and the coolant temperature sensor? does one go to the computer the other go to the idiot light on the low end gauge set? which does what?

The coolant temprature sending unit on a 4.0 is the on at the left rear of the block near near the head. It controls the temp gauge or idiot light. The coolant temprature sensor is the one mounted on the thermostat housing and is part of the emissions control system. It tells the computer what it needs to know about the operating temprature of the engine. They are not interchangeable.

That's what I thought. So the temperature sending unit (not the coolant temperature sensor) is what needs to be activated to see if the idiot light on the instrument cluster works. Is there a simple way to do that?

The Engine Temperature Sending Unit is the sensor that turns on the Temp Light. The sensor is at the rear of the engine next to valve cover. An easy way to check the sensor is to remove the connector at the sensor. Turn the key so the other lights come on. Then touch the connector pin to ground. You will probably need a paper clip or small wire. The light should turn on. If not...bad bulb or bad sensor. If the light does turn on, the sensor is bad. On my 96 Cherokee it was the sensor.

I have a 96 4.0 and i have put 2 new Temperature Sending Units (the sensor by the vavle cover) on it. The first one i broke off. but when i ordered it they gave me a sensor that had 2 prongs (not sure what you call them) sticking up. BUT my connector only has a slot for 1 not 2. It was like this everywhere i went. NAPA, AutoZone, Advanced Autoparts, Oreilys all had the same one so i called the dealer and had them crossreference the dealer part and it had 2 prongs also. Oreilys looked at the part it called for and motched it up with one that only has 1 prong and sold it to me and now...... it still dont work and i have $15 Less. Can anyone tell me if i should have a 2 wire connector on that? It does not look like it has been changed. i have a Guage not a light. My temp guage has never moved from the far left.

thanks in advance.

TJ

Go back to advance and tell 'em they cut off the wrong prong! No no, don't.. It's only supposed to have one wire whether it's a guage or a switch. Go to a dealership. I know it's high, but you need the RIGHT part, right?

I have a 96 4.0 and i have put 2 new Temperature Sending Units (the sensor by the vavle cover) on it. The first one i broke off. but when i ordered it they gave me a sensor that had 2 prongs (not sure what you call them) sticking up. BUT my connector only has a slot for 1 not 2. It was like this everywhere i went. NAPA, AutoZone, Advanced Autoparts, Oreilys all had the same one so i called the dealer and had them crossreference the dealer part and it had 2 prongs also. Oreilys looked at the part it called for and motched it up with one that only has 1 prong and sold it to me and now...... it still dont work and i have $15 Less. Can anyone tell me if i should have a 2 wire connector on that? It does not look like it has been changed. i have a Guage not a light. My temp guage has never moved from the far left.

thanks in advance.

TJ

The sensor you need is "TU236". I just changed my instrument cluster from lights to gauges. I had the same problem finding the correct sending unit.

did you figure this out? I'm having trouble finding where my temp sensor is for my guage. I found the wire for it, but I can't find the sensor that it needs to be plugged into, so I have no temp guage till I find the sensor on the engine. Its a 1 prong wire, purple with a stripe on it, don't remember the color of the stripe.

while standing in front of the jeep follow the valve cover to the back of the engine and you should see it in the far back on the top right hand side

yeah...... there isn't one there

I know where your talking about, I saw a bunch on some older jeeps at the junk yard today, my engine doesn't have one cause its a newer engine. But I don't know how to make the guage work with this newer engine.