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Old 12-23-2011, 01:39 PM   #1
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Merry Christmas everyone!

So I think a sensor went bad on my 93 YJ. All of a sudden my temp gauge is not working (it always shows the coldest reading). I have heat and there is ample coolant in the engine. Is this most likely the temp sensor? Or could it be something else?

If it is the sensor, where is it located and what type tool do I need to remove it/change it?

Thanks in advance

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Old 12-23-2011, 01:56 PM   #2
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Its probably the sensor, if its a 4 cyl its located at the rear of the head, drivers side near the end of the fuel rail area and just below the valve cover...

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Old 12-23-2011, 01:58 PM   #3
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Quote:
Originally Posted by Garyk
Its probably the sensor, if its a 4 cyl its located at the rear of the head, drivers side near the end of the fuel rail area and just below the valve cover...
Thanks! It's the 6 cyl
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Old 12-23-2011, 02:08 PM   #4
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Its also located in the same area on the i6..
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Old 12-23-2011, 02:09 PM   #5
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Quote:
Originally Posted by darkproximity
Its also located in the same area on the i6..
Cool I'll check that out! Thank you
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Old 12-23-2011, 02:43 PM   #6
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Same thing on my 93 I've had a couple of weeks,plenty of heat not overheating...gauge doesn't move
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Old 12-23-2011, 02:53 PM   #7
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Mine was like that so I wiggled the wire around and its been working ever since, so you might want to check that too
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Old 12-23-2011, 03:35 PM   #8
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temp sensor is for computor. temp sending unit is for the gauge. sending unit should be on the back of the head driver side.
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Old 12-23-2011, 03:50 PM   #9
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Originally Posted by AzWrangler93 View Post
Mine was like that so I wiggled the wire around and its been working ever since, so you might want to check that too
the wire on the sending unit, sorry
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Old 12-23-2011, 04:33 PM   #10
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Quote:
Originally Posted by AzWrangler93

the wire on the sending unit, sorry
Ok so it sounds like i dont need the sensor then. Anyone have a pic of the temp sending unit in the engine bay? Also how much does this cost?
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Old 12-23-2011, 06:17 PM   #11
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Its in the top of the head next to the firewall on the drivers side, has 1 wire coming from it.. its a small sensor.. trying to find out a pic
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Old 12-23-2011, 06:18 PM   #12
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Should be like 10-20$
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Old 12-23-2011, 06:26 PM   #13
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Thanks to the google images :-)
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Old 12-23-2011, 06:31 PM   #14
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Quote:
Originally Posted by darkproximity

Thanks to the google images :-)
Haha. I was just going to post that exact pic. Unfortunately, that sensor in the pic is not at that spot on my jeep
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Old 12-23-2011, 06:38 PM   #15
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Hmmmmmm motor swap?
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Old 12-23-2011, 06:41 PM   #16
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Quote:
Originally Posted by darkproximity
Hmmmmmm motor swap?
I don't think so. I guess its possible that I missed it with the flashlight because it was dark out. I can look again tomorrow when it's daytime
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Old 12-23-2011, 06:41 PM   #17
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The 96+ motors don't have a temp sender sensor, they pull their temp info for the gauge, from the computer, which is pulled from the sensor in the theromostat housing
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Old 12-23-2011, 06:43 PM   #18
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Quote:
Originally Posted by darkproximity
The 96+ motors don't have a temp sender sensor, they pull their temp info for the gauge, from the computer, which is pulled from the sensor in the theromostat housing
I'll snap a pic or two tomorrow and post. Is there an easy way to tell if it's NOT a 93 engine?
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Old 12-23-2011, 06:52 PM   #19
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The block casting date on the drivers side toward the back.. you'll have to get down under your driver side door and look on the back of the block.. it will literally tell you the date the block was cast...

If they used a complete donor motor I could tell from the valve cover.. they changed them in 96 too I believe
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Old 12-23-2011, 07:04 PM   #20
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Ok cool. I'll see what I can find out tomorrow. Thanks for your help.
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Old 12-23-2011, 07:07 PM   #21
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No problem ill be here :-)
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Old 12-24-2011, 11:09 AM   #22
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Ok so I found the sending unit...it was unplugged! I plugged it back in and now the gauge works fine. I'm wondering if when I had the shop replace my oil sending unit a week or 2 ago they for some reason unplugged that?
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Old 12-24-2011, 11:13 AM   #23
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I had to replace the sensor on my 93 4.0 just the other day. I found a plug which didn't lead to anything and thanks to help from this forum determined it was the sensor. The top of the sensor was still in the plug and I had to search long and hard to find the rest of the snesor in the engine block. Auto Zone has the sensor for about 15.00. I had to clean the area of the engine where the sensor goes to locate it. There is a wiring harnes located above the sensor and I suspect that is what broke mine off. Easy fix once you locate it.
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Old 12-24-2011, 12:09 PM   #24
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Quote:
Originally Posted by cjeezy
Ok so I found the sending unit...it was unplugged! I plugged it back in and now the gauge works fine. I'm wondering if when I had the shop replace my oil sending unit a week or 2 ago they for some reason unplugged that?
Thats weird.. maybe it just came loose?
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Old 12-24-2011, 12:12 PM   #25
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I had to relocate the sensor when I swapped to a 99 motor, we got creative and found a pipe plug that threaded into the water jacket drain hole, then tapped it to fit the sensor and extended the wire.. that was the only change to make to retain obd1 on the obd2 motor
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Old 12-24-2011, 03:50 PM   #26
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Quote:
Originally Posted by darkproximity
The 96+ motors don't have a temp sender sensor, they pull their temp info for the gauge, from the computer, which is pulled from the sensor in the theromostat housing
I have a question for you. I have a '92 YJ with the 2.5L in it and the engine was stolen out of it, the insurance company replaced the engine with a new rebuild. This all happened with the previous owner and this thread makes sense why I dont have a temp sending unit in the back of the engine, it must have a 96+ engine in it. Since my yj is a '92 and it normally uses a separate wire for the internal gauge and a separate wire for the ecu and now that the new engine in it only has 1 temp unit with no temp sending unit in the back of the engine, how can I add an aftermarket gauge inside the cabin so I can watch the temps? Right now the coolant temp gauge in the cabin of the Jeep doesn't work because it's not plugged into anything. Do I need to get a new thermostat housing that allows two plugs to go into it? If not how is everyone watching their engine temps? Any advice or links is appreciated how I can accomplish this.
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Old 12-24-2011, 03:57 PM   #27
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Lemme see if I cant find a link for ya.. im gonna have to do some research on the 2.5l block.. it might be a bit of an undertaking though as you'll probably want to drain your coolant as you'll be using an existing plug in the side of the block.. that or there might be a flat spot on the thermostat housing that you can drill and tap for the sensor.. either way you'll want a drill and tap to do the job and a wire tool to extend the line to the new location
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Old 10-10-2013, 07:46 PM   #28
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I have a 89 wrangler 2.5l, it will not start without priming.. have replaced the entire fuel system.. wondering if it might be a coolant sensor??? any thoughts?
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Old 11-18-2013, 08:20 AM   #29
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Thanks to the google images :-)
Is there a special tool to remover the sending unit. Can't find a wrench that seems to fit properly...metric or standard.

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