Hi everyone. I am the proud new owner of a very clean '95 F150 with the 300 I6 EFI motor and 5speed manual. The truck was an old man's who put only 80K on the ODO before I got it last week. It is my first Ford and the first American car I have owned in almost 20 years since I got out of MOPARs in my early twenties. I have been into vintage VWs for almost as long and know a bit about turning wrenches and using the "SEARCH" button on various forum pages.

With all of that out of the way, I have a non-working temp gauge. After using the aforementioned "search" button and reading many threads on this exact topic, I have some questions. First, I replaced the temp sender (the one with the single wire on the block) and got nothing. I also grounded the wire and again, nothing. So I am assuming it is either the wire itself or the gauge. So how do I do a continuity test on the wire and/or test the gauge itself. After all the threads I read, I still dont have a concrete example of where to go from here.

Oh and as a side note, with the key 'off', the needle points at "C". when I turn the key "on" the needle actually drops below "C" so it as if it is getting power.... not just a dead gauge. Any ideas?

 

Welcome to and congrats on your new Ford truck!

It sounds like bad ground at the gauge. I think all the gauges share the same grounding point, but unfortunately I'm not sure where that is so I can't tell you.

As for a continuity check on your wiring, the easiest way is to do it with a meter. Using the lowest resistance (ohm) range you have, touch the test leads together to get a point of reference. Then, with the wire unhooked from the temp sender and the gauge, touch one lead to one end of the wire and one lead to the other. As short as that wire is, you shouldn't see more than .5 ohm increase as compared to your reference number.

 

So I guess the next step in my Ford Truck learning curve is how to take apart the dash and get at the gauge cluster. Oh boy... Is the wire from the sender a straight shot to the back of the gauge? I am just thinking that I will have to open the cluster no matter what, but the wire disappears into a cluster f**k of a loom about 9inches away from the sender. It seems like it might be easier to run a new wire than try and pull the old one out. Of course, if its the gauge or a bad ground, that might be even easier still.

After driving it around for a while, I used the temp gun to check motor temps and they seem to be in line with what everyone says they should be. So thats good.

 

Is there or does there appear to be any aftermarket electronic installations in the cab or under the hood ???

You never know what the real story is until you find the PO's carnage !!!

I had an aftermarket alarm system removed from my truck just before I bought it.
When they initialy installed it they used the first ground wire they could find behind the cluster and removed it from the wiring harness connector.

Needless to say I had to do some custom wiring to get all of my gauges to work correctly.

Find yourself a good wiring diagram of the three (IIRC) connectors that plug into the the cluster. Take your time and don't get frustrated....compare pin positions against/with wire colors.
If all looks good with the wiring, gather up all the tools you used to remove the cluster and what you'd need to remove the temp gauge entirely from the cluster and find the nearest u-pick boneyard and remove a donor/their cluster and then their gauge......it should be way less expensive than buying the complete cluster.

And be warned.......don't touch or even try to clean off the white painted areas of the gauge itself to clean it up...........the paint will come off like it were chalk.
Just find an ideal replacement, handle it carefully, and call it good.

Good luck,

Bob

 

Now that you mention it, there is a Locktronics anti theft thingy under the dash. I might have to check that out. Where can I find a detailed pic of those plugs and their corresponding wires and what they do. I would love to find which wire the temp gauge is and if it has its own ground or shares with others.

 

That was the brand of alarm that was installed in my truck !!!!!

When I did my pinout I used a Haynes manual.
But........
Their wiring diagrams have been known to be incorrect at least I've been told.

The best diagrams would be the ones from the official FORD repair manuals.

If Subford Bill sees this post he may be able to provide the wiring schematic and pinouts you'll need.

You'll need the schematic for the cluster as well to see if/how the temp guage functions with all the other guages in the cluster.

And please take this little piece of advise, if there's suppose to be a pin in a connector, make sure to put one in there.
Some of those pins bridge other circuits in the cluster. ie. one pin marked as a simple ground may link three other circuits within the cluster.


Keep us posted,

Bob

 

On the way home this evening, I looked down and -voila!- my temp gauge was working with the needle firmly over the "r" in "normal". Then I had to stop for gas. When I restarted my truck, the gauge went back to its same old non-working self. And again, when i turn the key on, the needle actually goes from hovering over "c" to pegged below "c".

What the hell is going on?

 

It's not out of the realm of possibilities, but, you could have a sticking "open" thermostat instead of an electrical problem....

Bob

 

Yeah, I thought about that too, except for the fact that the temp gauge working/not-working is so intermittent that it rules out thermostat malfunction. For instance, I got in the truck this afternoon and the gauge worked straight away. I drove about 5 minutes to the store, the gauge registered the engine warming up. I got back in to start it.... Nothing. Again, the needle went the opposite direction...pegged below the "C".

Baffling.