replaced sending unit and sensor, replaced water pump and tstat, filled with coolant, now why is my temp gauge still not working? could it be a defective sending unit? i purchased TS334 sending unit.

 

Was your gauge working correctly prior to the replacements?
I would suggest unplugging the connector to the new unit, inspect for any dust/dirt, etc... and reconnect making sure that it is fully connected before making the assumption that the unit is bad. If you get the same result, it's certainly within the realm of possibility that you have a defective unit. But that way you've done your due diligence first.
Let us know the results.

 

You don't say what year you have, and that's very important here.

 

You can test the temp gauge by holding a lighter near the end (obviously unplug the sending unit from the back of the head, keep the wiring connected and turn the key to "on" before applying heat). If the gauge responds then the sending unit is at least reading temperature. I'd definitely check the connection first to make sure it's clean. Throw some di--electric grease on it before re-connecting just to be sure.

 

You might have an idiot light sending unit, which would only peg the gauge if it got too hot.

 

How many threads are you planning on starting regarding this? Help is available. Test your components, report back. It’s as simple as that.

https://www.cherokeeforum.com/f2/tem...orking-241322/

 

tested using lighter and wire on my sending unit. both the sender and sensor were replaced. what now?

96 cherokee

 

So did the gauge respond to the lighter?

If not then the problem is with wiring. If so then to clarify the gauge responds but the Jeep doesn't register any temp which would mean the coolant isn't contacting the sending unit.. which could be a number of things.

Please clarify so we can move forward with analysis.

 

i put a lighter to the sending unit, didn't work, i put a wire in the connector and to ground, and still nothing on the gauge. my coolant system was pretty bad from the previous owner, i don't believe the coolant system worked all the way through. so when you said that the coolant isn't hitting the sending unit could be it, i was curious. but wouldn't the gauge still work or register with both a lighter and wire test? so what else could it be?

 

So it's NOT the sending unit - if you got no response with a lighter you have an issue with something between the unit and instrument cluster.
Do you have a full temp gauge or just the idiot light? Looking at the part number it appears to be just the light. Assuming that so, then it could be as simple as the bulb being bad.
Pull your instrument cluster (it's just a few screws, I pulled a junkyard cluster in about 3 minutes.. lol.. it took 15 on my XJ since I was being careful.) Remove the temp bulb from the back and see if the bulb is bad (it probably is) - replace the bulb (194 I believe) and repeat the lighter test.

Those would be my next steps.

Actually that's not true. I'd swap the cluster for gauges rather than lights... which is why I was at the junkyard since my XJ originally had lights.

 

If it wasn't clear, I would NOT fully re-assemble the dash until testing the light works. If things aren't fixed with a bulb you're going to be testing wires.

I WOULD make sure that your engine compartment grounds are all clean and tight if that hasn't been reiterated.

 

From the original post, it appears there is a temp gauge, not just a temp light. Make sure you have the correct sensor, and make sure your ignition is in the “on” position during your tests. If you know for sure you are testing correctly and there is still no activity at the temp gauge, then PatHenry is correct in that the problem is somwhere between the sensor and gauge. In my mind more likely a bad gauge. If it were me, I’d pick up a spare gauge cluster from a junk yard. Should cost around $30. Find the cleanest one you can. I have a ‘96 and removal requires taking the cover off the steering column (2 screws, one of them is torx). Four screws in the bezel, and four screws holding the cluster in. It takes a little wiggling and fiddling to get the parts out, but it is quite easy to do. Just take your time.

 

To follow up on what Senor Martillo said - it's a very easy job to get the cluster out.
If you have gauges, you may want to double check the part you originally mentioned - TS334 looked like a switch rather than a sender when I looked it up. You need to have the proper switch/sender for your configuration. The unit LOOKS the same and has the same connector, but internally is different for lights (switch) or gauges (sender). If your part doesn't match the setup, it will be wonky.
So that's something to check. If you don't have gauges or you do and you get no reading - I do HIGHLY recommend following ElMartilo's advice and get a clean cluster with gauges, replace your current cluster and if you're "upgrading" (in other words going from lights to gauges), replace your temp switch with a sender and your oil pressure switch with a sender (they are interchangeable - no connectors or wiring changes or anything requiring more than std hand tools.. a good super deep 1" socket for the sender was key for the oil pressure side for mine..)

The gauge swap was one of the first things I did on my 95 and it's awesome.

 

I have looked everywhere and can not find the sensor anywhere. I can see the plug in attached to the wire harness. It is unplugged. I have even gotten under it and ran my hand all over the back side of the head. I climbed up onto the engine bay and looked everywhere back there and still do not see it. Is there a chance my 4.0 does not have the temp sending sensor? It is a 1994 cherokee country high output.

 

If the head was replaced with a 97+ then it would not have the port for the temp sender (the sender for 97+ is integrated into the CTS in the t-stat housing).

If that's the case, then you can drill a port into the t-stat housing and extend the wire from the original sender and it will work. It won't be as good as the original location (you won't see a temp reading until the t-stat opens) but that's the typical way the sender is relocated.