Kicking another dead horse here... re grounding the temp sending wire to see if the gauge jumps to H is not recommended in the "official" big, fat, Orange Ford shop manual... just fyi. I know, I know... there's more years of experience in this forum than craters on the moon... but since my research into this topic got me here... thought I'd share...

 

So do tell us how the orange book has us do the gauge test with no fancy tools in tool box?


I quick ground of wire to see if gauge moves is how I have ever done it for temp/oil/fuel gauges or even lights.
Dave ----

 

Hey Dave... sorry this took me a while... been under da hood today...

Just to be clear... we're talking about grounding the lead that connects to the temp sender... not the gauge itself... (tough to do without the IC in your lap!)

So... a few pics from the Great Orange Bible...

re the "warning"...



... and how to test the gauge without the "Rotunda Tester" as recommended...




... and a note about bench testing the gauge itself...



This Temperature Gauge worm-hole I'm in has me very curious about the gauge... and what it's REALLY telling me in run mode. And as usual... there are too many variables!

I may do a test on my temp sender and see the Ohm to Temp relationship...

 

Warning not to put 12 volts to the sender or sender wire/gauge.......No S**t!


So the bible said to first use "Rotunda Tester" that no one has in their toolbox.


Then use resisters to check gauge calibration and if not right replace the IVR and if that does not fix it replace the gauge.


For us trying to see if wiring & gauge work or if bad sender grounding the wire works. Besides the gauges are not that dead on to worry if calibrated or not.


oh thanks for posting that
Dave ----

 

Does your truck have the oil pressure gauge or the idiot light? If it has the gauge, that circuit can be used to troubleshoot the temp gauge.

The oil pressure, coolant temp, and fuel gauges are all the same electrically. They just have different markings on the face.

Disconnect the wires from the oil pressure and coolant temp sensors. Use a pair of jumper wires to connect the oil pressure circuit to the temp gauge, and vice versa.

Fire up the engine. The oil pressure gauge will now display the signal from the coolant temp sensor. The coolant temp gauge will now display the signal from the oil pressure sender. That should let you quickly figure out what component is at fault.

 

These gauges are thermal (spring relaxes when heated up) so i can see why The Bible says not to just ground the terminal, but in practice it works just fine if only done momentarily.

As usual, Gary has a great writeup on the ICVR, gauge testing and a solid state replacement.

Some members do have some of the Rotunda testers. Subford, 85lebaront2 and GaryLewis come to mind.

 

clever, KR... good one!

and Jim... I've been searching Gary's site and the EVTM pages (I'm actually waiting on delivery of my own copy but haven't seen his ICVR stuff yet... I'll head back there.

And the crazy in me would love to get my hands on the impossible-to-read hard copy of the electrical schem... any hidden corners of the internet that you know of that I haven't found yet?

 

Glad to post what I can...
speaking of posting... I found Gary's post https://www.ford-trucks.com/forums/1...ervations.html

I'm now an official geek.