Engine temp "dummy light" not working
CF Veteran
Joined: Jun 2014
Posts: 1,052
Likes: 1
From: PA
Year: 1994
Model: Cherokee
Engine: 4.0 HO
I have a '94 with idiot lights only.
If u turn the ignition switch to the on position,the coolant temp sensor light is not on. But it goes on when the starter is cranking, and goes off when the engine starts. I hope that helps.
Fyi, i am going to install a coolant temp guage.
If u turn the ignition switch to the on position,the coolant temp sensor light is not on. But it goes on when the starter is cranking, and goes off when the engine starts. I hope that helps.
Fyi, i am going to install a coolant temp guage.
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 103
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
The OEM part number for the switch (on head) is 56026710AB.
Rockauto has them.
http://www.rockauto.com/catalog/raframecatalog.php?ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=USD&ck[PHP_SESSION_ID]=rgs0c4vvge6gqbc47nbgfjlio2
Rockauto has them.
http://www.rockauto.com/catalog/raframecatalog.php?ck[ID]=0&ck[idlist]=0&ck[viewcurrency]=USD&ck[PHP_SESSION_ID]=rgs0c4vvge6gqbc47nbgfjlio2
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 103
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
Interesting - since we seem to have the same symptom, I wonder if you have a faulty / wrong sender as well (according to the post quoted below, the dummy light should NOT behave like this). My part # lines up with sender for light (not gauge), but still appears to be wrong.
Anyone else with a '95 XJ or similar with a dummy light out there to chime in whether a) theirs lights up upon ignition and b) if the light varies according to temperature?
Anyone else with a '95 XJ or similar with a dummy light out there to chime in whether a) theirs lights up upon ignition and b) if the light varies according to temperature?
According to the wiring diagrams the warning lamp is provided 12 VDC and is looking for a ground to illuminate.
The Coolant Temp Switch (on the head) provides the ground at a preset temp.
The ignition switch temporarily provides a ground to the warning lamp when the switch is turned to START, illumnating the warning lamp, then that circuit is opened when the switch is released to RUN. From this point onward, the Coolant Temp Switch will provide the ground.
The Coolant Temperature Switch has a one pin connector. The Switch is grounded through it threads to the head. If you wrapped the switch threads with Teflon tape, or used a non-conductive sealant on the threads, you may not be getting a good ground connection
for the switch.
If you had a temp gauge, its Sending Unit would have a one pin connector as well. The Switch is a simple open/close switch and the gauge Sending Unit is a variable resistor.
With a Temp Sending Unit installed the light could vary relative to temperature.
Sending Unit OEM part number is 56027012.
Last edited by CCKen; Sep 9, 2014 at 08:35 AM. Reason: Revised (in blue)
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
I don't have a '95 XJ but I can read and understand the English language.
According to the wiring diagrams the warning lamp is provided 12 VDC and is looking for a ground to illuminate.
The Coolant Temp Switch (on the head) provides the ground at a preset temp.
The ignition switch temporarily provides a ground to the warning lamp when the switch is turned to START, illumnating the warning lamp, then that circuit is opened when the switch is releaded to RUN. From this point onward, the Coolant Temp Switch will provide the ground.
The Coolant Temperature Switch has a one pin connector. The Switch is grounded through it threads to the head. If you wrapped the switch threads with Teflon tape, or used a non-conductive sealant on the threads, you may not be getting a good ground connection
for the switch.
If you had a temp gauge, its Sending Unit would have a two pin connector. The Switch is a simple open/close switch and the gauge Sending Unit is a variable resistor.
With a Switch the light will not vary relative to temperature.
According to the wiring diagrams the warning lamp is provided 12 VDC and is looking for a ground to illuminate.
The Coolant Temp Switch (on the head) provides the ground at a preset temp.
The ignition switch temporarily provides a ground to the warning lamp when the switch is turned to START, illumnating the warning lamp, then that circuit is opened when the switch is releaded to RUN. From this point onward, the Coolant Temp Switch will provide the ground.
The Coolant Temperature Switch has a one pin connector. The Switch is grounded through it threads to the head. If you wrapped the switch threads with Teflon tape, or used a non-conductive sealant on the threads, you may not be getting a good ground connection
for the switch.
If you had a temp gauge, its Sending Unit would have a two pin connector. The Switch is a simple open/close switch and the gauge Sending Unit is a variable resistor.
With a Switch the light will not vary relative to temperature.
Muddy the waters with facts once again...............
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