Temp gauge goes from normal to cold so does heat

SOURCE: u1073 scp code

Hi MaddMD!

This is partly an answer to part of your question, and part clarification request

According to: http://www.ford-trucks.com/forums/141841-odometer-test-codes.html the U1073 SCP is defined as:
"U1073 SCP (J1850) Invalid or Missing Data for Engine Coolant PCM REFER to Powertrain Control/Emissions Diagnosis (PC/ED) manual"

Okay.... I need to research what exactly the above means, but I also need a little more information from you.

• What engine do you have?
• Were there any malfunction indicator lights (MILs)?
• How did the overheating occur (stopped at idle, going down the road, A/C on or off?), and how drastic was it? (i.e.: Was there loss of engine oil, any significant smoking or steam out of the engine bay, significant loss of power?)
• Do you know what caused it to overheat? (Low coolant, fan failure, broken belt, water pump problem, stuck thermostat)
• What prompted you to change the temp sensor?
• Is it an electric or engine driven radiator fan?

The way you describe the situation now, without considering the code, it sounds like the radiator fan is not moving enough air across the radiator to remove heat from the coolant. Turning the heater on causes the heater core to act as a kind of substirute radiator and thus lowering the engine temp. This can be verified, if the truck is driveable, by going down some open road with the heater on to cool the engine, switching off the heater and then see if the temp comes back up while moving at least 30 mph or if it stays down. If it stays down while moving, try stopping and idling for a couple of minutes and see if the temp then goes hot... If so, the fan is not working as it should and should be looked at. Don't let it get too hot, and see if you can get it to an AutoZone to have them perform a free diagnostic scan and see what OBD-II trouble codes are set.

Get back to me by posting a comment to your problem with whatever further information you can gather and also by sending me an e-mail at [email protected] so that I'll know to check that information, and in the meantime I'll check with some of my Ford tech friends as to the signicance of the U1073 SCP code.

Thanks!
WildBill

SOURCE: 2000 Ranger 4 cyl auto w/ac, no heat, temp guage doesn't move

follow the upper radiator hose to ehrer it connects to the engine, the t-stat is right there
olso remove all that other stuff in needed

SOURCE: Temp gauge fluctuates from normal, up to blow Hot,

Sounds like a head gasket problem

SOURCE: replaced thermostat,heater core and still no heat

the dommed part of the T-stat goes up, it won't go in backwards as memory serves me, what u almost certainly have going on here is the Air temperature control electric bend door actuator s defective, and the door is stuck in the cold air position in the heating/ac duct, to replace this the dash must be removed from the car..

SOURCE: 1995 ford ranger with 4.0 auto, I have very

Hi. There are several ways to test the opening temperature of a thermostat. Use this procedure to confirm that you are running the correct rated thermostat.

One method does not require that the thermostat be removed from the engine.

* Remove the radiator pressure cap from a cool radiator and insert a thermometer into the coolant.
* Start the engine and let it warm up. Watch the thermometer and the surface of the coolant.
* When the coolant begins to flow, this indicates the thermostat has started to open.
* The reading on the thermometer indicates the opening temperature of the thermostat.
* If the engine is cold and coolant circulates, this indicates the thermostat is stuck open and must be replaced.

The other way to test a thermostat is to remove it.

* Suspend the thermostat completely submerged in a small container of water so it does not touch the bottom.
* Place a thermometer in the water so it does not touch the container and only measures water temperature.
* Heat the water.
* When the thermostat valve barely begins to open, read the thermometer. This is the opening temperature of this particular thermostat.
* If the valve stays open after the thermostat is removed from the water, the thermostat is defective and must be replaced.
* Several types of commercial testers are available. When using such a tester, be sure to follow the manufacturer's instructions.
* Markings on the thermostat normally indicate which end should face toward the radiator. Regardless of the markings, the sensored end must always be installed toward the engine.
* When replacing the thermostat, also replace the gasket that seals the thermostat in place and is positioned between the water outlet casting and the engine block.
* Generally, these gaskets are made of a composition fiber material and are die-cut to match the thermostat opening and mounting bolt configuration of the water outlet.
* Thermostat gaskets generally come with or without an adhesive backing. The adhesive backing of gaskets holds the thermostat securely centered in the mounting flange, leaving both hands of the technician free to align and bolt the thermostat securely in place.