What the ffffffff is an ECT circuit??

[Boss 351]

pulled that code before I changed my faulty injector... I didn't have time to recheck anything, but now I have another problem I think... but what is an ECT circuit?

 

[rd]

Engine Coolant Temperature. There is a separate temp sender for the computer, separate from the one for the gage.

 

[VG30DE]

Its the one on the black pipe that goes up over the passenger side of the intake. Right on the front of the motor.

 

[65ShelbyClone]

Those would be the metal heater tubes that go back to the firewall. Check the plug or the wires on the sensor, maybe it got bumped in the injector swap.

 

[jrichker]

There are two ECT codes that you can get. For the sake of getting all the info
at once, I posted both of them.

Code 21 – ECT sensor out of range. Broken or damaged wiring, bad ECT
sensor. Note that that if the outside air temp is below 50 degrees F that
the test for the ECT can be in error.

The ECT sensor has absolutely nothing to do with the temperature gauge.
They are different animals. The ECT sensor is normally located it the RH front
of the engine in the water feed tubes for the heater.

The ACT & ECT have the same thermistor, so the table values are the same

ACT & ECT test data:

Use Pin 46 on the computer for ground for both ECT & ACT to get most
accurate readings.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5
volts. It is a good number if the ACT is mounted in the inlet airbox. If it is
mounted in the lower intake manifold, the voltage readings will be lower
because of the heat transfer.

Voltages may be measured across the ECT/ACT by probing the connector
from the rear. Use care in doing it so that you don't damage the wiring or
connector.

Here's the table :

68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61

Note that all resistance tests must be done with power off. Measuring
resistance with a circuit powered on will give false readings and possibly
damage the meter.

Ohms measures at the computer with the computer disconnected, or at the
sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

Code 51 Engine Coolant Temperature (ECT) sensor signal is/was too high -
Possible bad ECT sensor, or wiring. Possible missing signal ground -
black/wire wire broken or bad connection. With the power off, measure the
resistance between the black/white wire and battery ground. You should see
less than 1 ohm. Check the same black /white wire on the TPS and MAP
sensor. More than 1 ohm there and the wire is probably broken in the harness
between the engine and the computer. The 10 pin connectors pass the
black/white wire back to the computer, and can cause problems.

Use Pin 46 on the computer for ground for both ECT & ACT to get most
accurate readings.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Voltages may be measured across the ECT by probing the connector from the
rear. Use care in doing it so that you don't damage the wiring or connector.

Here's the table :

68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61

Note that all resistance tests must be done with power off. Measuring
resistance with a circuit powered on will give false readings and possibly
damage the meter.

Ohms measures at the computer with the computer disconnected, or at the
sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

Diagram courtesy of Tmoss & Stang&2birds

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/

http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif