Hello,
I have a 1998 E350 with a 5.4 engine. Having some problems with the temp sensors. I just bought the van and the temp gauge on the dashboard never came off cold. I did use an infrared temp tool and the engine is getting up to temp. The sensor/sender right behind the alternator was changed with an aftermarket part. Not even sure if that was the right part to change. Now the dashboard gauge goes from cold to hot in the blink of an eye. I called the local Ford Dealer and was told I needed either the Engine Coolant Temp Sender(part# F65Z10884AA) or the Engine Coolant Temp Sensor (part# 9U2Z12A648A). My question, is the part right behind the alternator the sensor or sender? And also, where would the other one be? Which one controls the dashboard gauge and which one goes to the ECU? The good fella who answered the phone at the Ford Dealer couldn't help me.

 

Engine temp sensors are usually screwed into the head or the thermostat housing. They might have a 5 volt reference voltage coming into the sensor a ground and a signal wire.
Temp senders usually have 3 wires while engine hot sender will have only 2 wires..If the temp gets HOT the 2 wire switch closes and the HOT light comes on ,on the dash.
The signal wire tells the temp gauge the temp of the engine.

 

OK button not clickable because Engine size is not selected. Which 5.4L? If you are unsure reply with your VIN here.
In the meantime do you have a scanner that can read live data to retrieve the current ECT temperature? If the value looks fine you are ok.

 

In the Ford Service Manual they refer to all gasoline engine "Coolant Temperature Sensor" and Diesel as "Coolant Temperature Sender".

I'm not saying all gasoline engines use the same part, just the same name.

5.4L wiring diagram attached

 

Thanks for the replies, the VIN is 1FBSS31L5WHA63218

 

 

The sensor/sender right behind he alternator is the one I changed, not sure if that was the correct one. The one in the picture, does it go to the dashboard gauge or the module?

 

Locate C137 as shown above.

R/W = red/white.
The other end refer to etinpa's diagram above, Y/R = yellow/red and it connects to G203 ground point with ground signal at all time.
There will be continuity on the R/W wire (unless yours is broken) from the sensor to the cluster pin 9. The needle moves based on the resistance reading.




Check torque spec above. And bleed your cooling system afterward.

 

This does go back a little, but very few of the manuals tell you , the temp gauge itself contains a voltage regulator feature internally that provides the correct voltage to the other gauges.Older systems used to use a voltage regulator mounted on the back of the instrument panel circuit board.
If you are getting incorrect readings ,you might want to verify the correct voltage is coming off the temp gauge.

 

Refer to the symbol of C137 etinpa provided above, so the sensor is thermistor. It doesn't matter the signal source is 12v or ground. But the Y/R (yellow/red) wire is terminated at G203 ground point hence a ground signal source. So pin 9 on cluster should have ground signal at all time check continuity can tell. To check resistance reading of course ohmmeter is needed.