Coolant Temperature Gauge not Working

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Aug 11, 2016 | 09:35 PM

kwozz48

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Joined: Sep 2015

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Coolant Temperature Gauge not Working

Hey everyone, I know there are a few posts regarding this issue on this forum, but I haven't found any that are the same as mine. So let me know if there's already a solution somewhere.

Basically my coolant temperature gauge either reads as the hottest it can be, or the coldest. It doesn't jump around a whole bunch, but it's always all the way to one end or the other. From what I've read there seems to be a lot of different temperature sensors, so I get a little confused with all of the abbreviations, but I'm fairly certain I checked the correct one, next to the thermostat housing. Using a multimeter I checked the resistance of the sensor, and it was around 600 ohms about 30 minutes after it had been driven. I'm not sure if this is where it should be or not, but it was rising as the truck cooled off.

Anyway, I'm not sure if I just tested the sensor incorrectly or if there could be another issue. A friend of mine suggested that the thermostat may have gotten stuck or something, but it doesn't seem like the gauge would switch at all if that were the case. If anyone knows what I should check to try and fix this, please let me know. Thanks!

Aug 12, 2016 | 06:25 AM

Rikster-7700

Fleet Mechanic

Joined: Aug 2006

Posts: 1,465

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From: Jacksonville, FL

do you have an auto or manual tranny?

Aug 12, 2016 | 06:35 AM

Tugly

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Joined: Jan 2011

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From: Puget Sound

I wonder if somehow a wire was crossed and you either have the wrong connection to the wrong sensor - or the wrong wires to the wrong pins. Has there been any electrical muckery going on under the hood by the PO?

You are talking about the gauge on the dash, right?

Aug 12, 2016 | 08:14 AM

kwozz48

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My transmission is automatic, sorry should've mentioned that initially. And I'm not sure what you mean by the PO, but I don't believe anyone has been messing around with the wiring underneath the hood. I've only had the truck for about a year, and the gauge hasn't been working the whole time, so I'm not 100% sure. And yes I do mean the gauge on the dash, just below the trans. temp gauge.

Aug 12, 2016 | 10:07 AM

Walleye Hunter

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Joined: Mar 2014

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From: Douglassville, PA

Quote:

Originally Posted by kwozz48

PO=previous owner, they tend to monkey around with stuff under the hood. I'm no expert here but I would swap out that sensor first, it sounds like the gauge is working. Remember Ford only, I tried cheating on this one and got a bad one right out of the box. You can change it without draining the system, just put a bucket under there and be quick.

Aug 12, 2016 | 10:34 AM

AllaboutMPG

Logistics Pro

Joined: Oct 2011

Posts: 3,953

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From: Mcdonough, GA

Quote:

Originally Posted by Walleye Hunter

Remember Ford only, I tried cheating on this one and got a bad one right out of the box.

X2 on oem for this sensor. I got one from Rock Auto and it was DOA. They refunded my money and didn't even want the sensor back.

Aug 12, 2016 | 11:03 PM

retiredsparky

Elder User

Joined: Sep 2011

Posts: 979

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From: Vancouver

If a new sensor doesn't do the job, there is likely a loose connection in the wiring harness.

When you install the new sensor, inspect the connector for corrosion and loose connection. And of course use thread sealant. Ford dash modules don't have a history of bad connections and failures like the GM trucks and cars do, but that is a possibility.