Engine temperature gauge is inoperable?

1990 FORD RANGER
68,000 MILES • 2.9L • 6 CYL • 2WD • AUTOMATIC
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RICK WILLHITE
My temperature gauge is inoperable. I tested the sensor, and it is good. Is there a fuse or frangible wire I can check? I've seen a partial wiring diagram on-line that shows an inline device marked 1 and labeled C105, but do not know what it indicates. What else am I missing?
Jan 18, 2025 at 10:40 AM
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STRAILER
  • ✓ASE Certified Mechanic
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  • ASE Certified Mechanic
There is just a blk/lb wire that goes from the sender to the cluster, so I would do a continuity test on that wire and if good replace the cluster with a rebuilt/used unit.

This guide will help with the test:

https://www.2carpros.com/articles/how-to-check-wiring

Here is the wiring diagrams for the coolant temperature sender so you can see how the system works. Check out the images (below). Please let us know what happens.
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Professional Diagram for 2CarPros Members
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Jan 18, 2025 at 1:25 PM
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