1998 ford f150 coolant temp gauge max hot

This topic has 7 replies, 3 voices, and was last updated 9 years, 6 months ago by David.

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May 14, 2015 at 4:12 am #663872
ray Jenkins
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my coolant temp gauge reads hot at all times with the key on
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May 14, 2015 at 4:22 am #663874
Allan
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Hello 🙂
Try unplug Connector at coolant temp sensor and see if gauge goes Down. if it does it is the sensor, if not the pull Down ref signal is short too ground somwere in harnes or gauge.
May 14, 2015 at 4:26 am #663877
ray Jenkins
Participant
i have unplugged the sensor with no change and tomorrow i will try adding ground to the sensor
May 14, 2015 at 4:41 am #663879
Allan
Participant
Ok.. Here you have wiring diagram.. But adding ground will not work i think.. becouse ref signal must alreddy be grounded for gauge show max temp..
Attachments:
- f150instrument-cluster.pdf
May 14, 2015 at 5:04 am #663881
ray Jenkins
Participant
so if i bring ref voltage down the gauge should come down with it and if so i have an open circuit?
May 14, 2015 at 5:21 am #663882
Allan
Participant
No, ref voltage (5V i belive). if high resistance in sensor ( low temp) then ref votage i high. and low resistance (high temp) ref voltage low.
May 14, 2015 at 5:27 am #663883
ray Jenkins
Participant
ok im good now i understand, i will look at it tomorrow and let you know what i find
May 14, 2015 at 5:29 am #663884
David
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If you have unplugged the sensor and the gauge is still showing hot, your gauge is faulty.
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