HELP !!!!????!!!! please ..

[TinyToon]

i have a 99 expedition 5.4L the ECT (engine coolant temp.) sensor is shorted out and i need to change it .. my question is can anyone tell me where it's located ?? i have already changed the CHT (cylinder head temp.) sensor , all the books and people i have referred too all are dead ends .. (behind the alternator , in thermostat housing , and in driver head by the exhaust manifold ) all are dead ends .. can anyone help me find the sensor ??? dealer tells me they will locate it for $250 dollars and that's pathetic highway robbery .. do to the sensor telling ECU the engines cold it has increased my fuel consumption to raise the engine to its operating temp. a difference from 18/19 MPG to 9.2/9.7 MPG ..

 

[ELVATO]

The only thing in the manual that mentions the ECT is for the 4.6L engine and gives the picture attached.

Also mentions the following:

The ECT sensor:

-sends the PCM a signal indicating engine temperature.
-resistance decreases as coolant temperature increases


But, when looking at the wiring diagram, it mentions that there is one on the top of the 5.4 engine (lists location as "Engine,top"). The connector going to it will have two wire, a light green w/ red stripe, and a gray w/ red stripe.

Hope that helps.

 

[Bow Down]

Try looking at the bottom tank of the radiator..

 

[TinyToon]

love my 5.4 but ready to shoot it (44 MAGNUM)

well no ECT sensor in my 5.4L yet still gauge down on the cold mark and when i get up to about 2500 RPMS the idiot light comes on also , no clue why my CHT is reading the fallowing codes

P1289 -- CHT out of range-high input
P0128 -- coolant temp. always low

engine not overheating , new thermostat , new CHT , and coolant level is at correct limit ..

 

[TinyToon]

well i disconnected the CHT from the harness and my temp. gauge still done the same thing .. shows its not the CHT sensor , does anyone have any ideas ??
PLEASE .....

 

[smo0othride]

The 1999 should not have an ECT sensor, they programed the PCM to do all the math through the CHT Sensor. The 97 -98 5.4L used both ECT and CHT Sensors.

If you want to varify this though, here's some info on how to find the ECT sensor:

c107 is the ECT sensor in the pic.

The ECT switch is on the driver's side, underneath the intake manifold,with a pigtail connection to the wire harness behind the thermostat housing.

 

[TinyToon]

can anyone get me the wiring schismatic for this 99 Expy please ??? just the engine harness from the ECM to the engine components ...

 

[ELVATO]

This might help?

You're looking for the wire with a yellow with a light green stripe going to the PCM harness. Do as projectSHO89 suggested, and do a continuity test from the sensor harness to the PCM side of the harness.

 

[TinyToon]

thx for the schismatics thats what i needed to do the test on it , i didn't know if it changed color b4 the ECM .. well workin 6p to 6a tonite so when i get off in the mornin ill check it and post results .. thx again guys

 

[TinyToon]

projectSHO89 and ELVATO thx guys , i bypassed the harness and wired from the ECM to the CHT with the wire u described EL and wahlah works like a charm .. i greatly appreciate the help guys