Strangeness With My Coolant Temp Gauge - JeepForum.com
 
LinkBack Thread Tools
post #1 of 6 Old 08-22-2016, 10:41 AM Thread Starter
DLYoung1
Registered User
1993 XJ Cherokee 
 
Join Date: Dec 2006
Location: Central Texas
Posts: 119
Strangeness With My Coolant Temp Gauge

I have a weird problem on my '93XJ in the instrument panel. The coolant temp gauge is behaving very erratically. At cold startup, the gauge works correctly, showing the engine coming up to working temp. Not long after, I will see the gauge start "going intermittent" (falling to 0 and back to functioning) in rapid cycles. And this is the strange part. It will fall to 0 and stay, but comes back when I hit the accelerator. Back to 0 as soon as I let off the gas.

It is obviously an electrical issue. I went through the FSM and found that several sensors under the hood (MAP, CPS, TPS, O2, and more) all share a common ground, along with the TCM. All other sensors seem to be working fine.

I don't want to throw parts at a new temp sensor if it's really a ground issue. The gauge functioning when I hit the gas and downshift and it sharing ground with the TCM has me intrigued, Anybody seen this before?


DLYoung1 in Texas
'93 Stock XJ, 4.0, 2wd, AW4 tranny
DLYoung1 is offline  
Sponsored Links
Advertisement
 
post #2 of 6 Old 08-22-2016, 08:42 PM
getterdun
Registered User
 
Join Date: Mar 2016
Location: Summerville
Posts: 143
If the other sensors were experiencing the same fluctuations, then checking their common ground would make sense. But, since they function normally, I'm more inclined to suspect the problem is with the coolant temperature sensor, a loose connection there, the wire running from there to the dash, or the connection to the gauge. I would start by disconnecting and inspecting both ends of the connector at the temperature sensor. I'd also examine the wires running to the sensor. If these are okay, I'd hook up a multimeter to check the ohms across the temperature sensor when the temperature gauge starts fluctuating. If it's the sensor, I'd expect to see the same fluctuations.

2001 Cherokee Sport
getterdun is offline  
post #3 of 6 Old 08-23-2016, 08:40 AM Thread Starter
DLYoung1
Registered User
1993 XJ Cherokee 
 
Join Date: Dec 2006
Location: Central Texas
Posts: 119
Thanks for the input. If I want to check the resistance across the sensor terminals, what am I looking for? Does the sensor "talk" to the PCM by ramping the resistance up and down relative to the coolant temp? So I would see wild fluctuations at the terminals, the same as the gauge?

DLYoung1 in Texas
'93 Stock XJ, 4.0, 2wd, AW4 tranny
DLYoung1 is offline  
 
post #4 of 6 Old 08-23-2016, 09:49 PM
getterdun
Registered User
 
Join Date: Mar 2016
Location: Summerville
Posts: 143
I just did some searching for the coolant temperature sensor for a 1993 XJ and learned that it actually has two, one in front for the computer, and another at left rear of engine for the gauge. See if this link helps: https://www.jeepforum.com/forum/f12/t...orking-858406/.

2001 Cherokee Sport
getterdun is offline  
post #5 of 6 Old 08-25-2016, 03:45 PM Thread Starter
DLYoung1
Registered User
1993 XJ Cherokee 
 
Join Date: Dec 2006
Location: Central Texas
Posts: 119
Bingo! Thanks for the input. A quick look at the REAR temp sensor shows the probe wire pulling out of the body of the sensor (it sits in a cavity of epoxy or something like that). I jammed it back in for now. Working fine until I can get it replaced. Thanks again.

DLYoung1 in Texas
'93 Stock XJ, 4.0, 2wd, AW4 tranny
DLYoung1 is offline  
post #6 of 6 Old 08-25-2016, 08:18 PM
getterdun
Registered User
 
Join Date: Mar 2016
Location: Summerville
Posts: 143
Glad to hear you got found the problem.

2001 Cherokee Sport
getterdun is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome