Ok I just need some clarifacation here 1992 3.0L manual trans

I assume she asked the shop about the Gauge on the Dash Always Reading Cold (Never makes it into the Normal Range on the dash Gauge) and makes ZERO sense to me why Ford did it this way. IMO
To have a Snowball Chance in you know what you Must be able to see what the PCM is Seeing if there is a Problem

So I guess Shop recomended a Thermostat and Water Pump Newer Maybe 2months AGO she had the Shop change them and the Serpintine Belt. When I scanned for DTC a week ago I did get a DTC for Low Coolant temp or something along those lines. IDK if the DTC was from Before the New Thermostat or Not. Maybe I should just scan it again anyways!!!

I did find Both ECT Sensors today

I Saw the Bigger ECT sensor the one with 2 Wires coming Off it a week ago when I started wrenching this truck

I found the Smaller one Today Next to the thermostat as well it was Kinda Hidden under the Wire Harness that runs threw right there


So I am thinking its just a Bad Sensor Unit going to the Dash or a Wireharness issue .
Or a Very Very Very Slim chance the New thermostat is Stuck open or weak spring


So Tell me if I have this Right Below

The Bigger 2 wire sensor goes to the PCM????????

The Smaller Single Wire sensor goes to the Dash Gauge????????




So is there any Chart that shows what I should have Resistence/volts wise that Corralates to Temp??? I do have a DVM to check them with

 

Just to clarify -- are you getting a scan code failure for coolant temp AND a low gauge reading? That's 2 sensors, not likely that they're both bad.

How about the heater?

Ford's generally had 2 wire units to the PCM and one wire to the dash gauge.
Not positive about Rangers, but pretty sure.

To see for sure:
Pull the single wire off and check your gauge ( key on ). Then ground the the wire and check again. Gauge should move -- proving that it's the coolant sensor for the gauge.

A Chilton's, Motor's or whatever should have the temp sensor values -- at least a couple to check it against. Your local library probably has them if you don't want to buy one. Autozone used to have on line service info -- not sure if they still do.

I had a brand new thermostat -- installed at a shop -- fail almost immediately. You hear about it fairly often.

Good Luck,

hj

 

If there is a coolant temperature-related code then you are probably looking at either a bad or unplugged ECT, or an "open" in the ECT circuit (cut wire, for example).

As mentioned, the ECT is the 2-wire sensor.

 

If you suspect a faulty Engine coolant temp sensor, go to the Ford Fuel Injection site link I posted in your other thread & it'll have a resistance range chart for the Engine coolant temp sensor. If its resistance range is also out of whack, the computer should be upset with it & you should have a CEL lit & a trouble code set.
A faulty ECT can cause the computer to get confused about what to do about fuel trim & closed loop operation, so mpg & driveability can be adversely affected.

As ford2go has said, if the Dash temp gauge single wire is grounded through a resistor that matches its sensors resistance range, it should move up scale. If its grounded without a resistor in series with the wire, it'll slam the meter movement full scale hot, so don't leave it connected that way long, just long enough to check the movement.

The Dash temp sensor resistance range typically falls between 74 ohms Cold, to 9.7 ohms Hot, so if you use, say a 10 ohm resistor in series to ground with the single wire Dash temp sender wire, the Dash temp gauge should move upscale to Hot, unless as Rockledge has suggested, the conductor to the gauge is open circuit, or the gauge is faulty or its movement is stuck.
More thoughts for consideration, let us know what you find.

Rockledge, long time no post, really good to see you on the forum again!!!!

 

OK Great Info as usual Guys

I am going to Mess around with it this weekend

There is NO CEL at this time and I will Scan For DTC again

PAW PAW I remember that Link you gave me For some reason had it in my mind that the scale was for the Two Wire sender But sounds like it works for Both

She did have the thermostat & Water Pump replaced
I think what happened is She saw the Dash Gauge reading Low and thought she needed a new thermostat so took to a Shop and they Did Both WP and Thermostat. Maybe they told her the WP Leaked IDK water under the Bridge Now. Just Dash Gauge still reads Cold However I do beleive the ECT is right where it Needs to be after warmed up but just want to Make Shure

Will do some testing and try to see where I stand with it this weekend

Thanks for the help and I will report back

 

BTW I reped everyone

But I got to spread the Love before it will let me Rep PawPaw again

thanks Guys

 

The fuel injection site is for the computer engine temp sensor numbers, the other values I posted are typical values for the dash gauge coolant temp sensor. You can disconnect each temp senders wires & use your multimeter to check their resistance value referenced to the temp of the coolant when you make the measurement & thus determine if either temp sending unit has a problem. With a substitute resistor in series with the dash senders lead to ground, you can determine if the dash gauge & its wiring are ok & kinda calibrate its movement.

 

You might want to find out if they installed a 180 or 195 degree thermostat.

 

Thanks paw paw. I'm glad to see that you're still here giving out good, sound advice to people.

 

If they did not install a genuine Motorcraft thermostat, expect to have problems. Every non-ford thermostat I have used in recent years opened and got stuck open way before the rated temperature.

 

I totaly Agree with the Above^^^^


I have had thermostat problems in my big truck the Spring gets weakened threwout the summer then Winter comes and it Runs Cold

The Diesels are VERY Dependant on a Properly working thermostat since no spark to ignite Air/Fuel Mix

Ford OEM is the only thing that Lasts

 

going to be a day before I get back to this She is driving it today