Cooling fan still not working...

[CarVolvo]

so if this is the case of the coolant sensor...could you not just jump or cross the connector for it to see if the circuit would then be open?

Or will that cause a melt down? Just asking!

[Trilarry]

CV
I was just guessing with the breakdown in the sensor(short circuit), If the resistance is super high this would cause the fan not to come on but the fault would more likely be in the wiring not the ECT. And according to the excerpt below it would indicate a short circuit in the wiring between the ECT and the ECM.

To answer your question it looks like it would be a short circuit not a meltdown. A low or high signal will set a code of 116 or 117 indicating a fault.

I sure hope ROMBIJR let us know what it was. I'm very curious. I'm betting on a connector. This excerpt is only for checking for a bad ECT not for why the fan is not working, this very well could be a rabbit trail.
Excerpt (sorry about the long Post)
Code 116, 117, 118 (Engine Coolant Temperature Sensor Signal)
1) If ECM receives a signal from ECT sensor which indicates a
temperature less than -49 �� F (-45 �� C), or greater than 300 �� F (150 �� C),
this is interpreted as a fault and DTC 1-2-3 is set.
2) If Codes 3-1-4, 4-1-1, and/or 4-1-3 are set, check ECT
sensor, CMP sensor, TP sensor, and EGR temperature sensor joint
connector terminal A18 on ECM for signs of contact resistance and/or
oxidation. If no other codes are stored, go to next step.
3) If fault is permanent, go to next step. If fault is
intermittent and signal is too high, check all connectors for an
intermittent open or short circuit to voltage. If fault is
intermittent and signal is too low, check wiring between ECT sensor
connector terminal No. 1 and ECM terminal A31 for an intermittent
short to ground.
4) If fault is permanent and signal is too low, go to step
10). If fault is permanent and signal is too high, turn ignition off.
Wait 90 seconds, then disconnect ECT sensor. Connect an ohmmeter
between ECT sensor connector No. 2 and ground.
NOTE: Fan run-on must be allowed to finish before taking
resistance measurements.
5) If ohmmeter shows about zero ohms, go to next step. If
ohmmeter does not show about zero ohms, go to step 7).
6) Turn ignition on. Disconnect ECT sensor connector. Connect
voltmeter between ECT sensor connector terminal No. 1 and 2. If
voltmeter shows about 5 volts, go to step . If voltmeter shows about
zero volts, go to step 9). If voltmeter shows more than about 5 volts,
check wiring between ECT sensor connector terminal No. 1 and ECM
terminal A31 for a short to voltage, then check resistance between ECT
sensor terminals. Ohmmeter should show about 2200 ohms. If resistance
is incorrect, retest using a known good ECT sensor.
7) Ensure ignition is off. Disconnect ECT sensor connector.
Check ECM connector for poor contact and/or oxidation. Reconnect ECM
connector. Connect an ohmmeter between ECT sensor connector terminal
No. 2 and ground. If ohmmeter shows about zero ohms, code is caused by
poor contact in ECM connector. If ohmmeter does not show about zero
ohms, check wiring between ECT sensor connector terminal No. 2 and ECM
terminal A18 for an open circuit.
Ensure ignition is off. Disconnect ECT sensor connector.
Connect an ohmmeter between ECT sensor connector terminals No. 1 and
2. If ohmmeter does not show about 2200 ohms, repeat test using a
known good ECT sensor. If ohmmeter does show about 2200 ohms, check
for poor contact at ECT sensor connector.
9) Ensure ignition is off. Disconnect ECT sensor connector.
Ensure ECM connector has good terminal contact. Reconnect ECM
connector. Turn ignition on. Connect voltmeter between ECT sensor
connector terminals No. 1 and 2. If voltmeter shows about 5 volts,
check for poor contact at ECM connector. If voltmeter does not show
about 5 volts, check wiring between ECT sensor connector terminal No.
1 and ECM connector terminal A31 for an open circuit.
10) If fault is permanent and signal is too low, turn
ignition off. Disconnect ECT sensor. Turn ignition on. Connect
voltmeter between ECT sensor connector terminal No. 1 and ground. If
voltmeter shows about 5 volts, retest system using a known good ECT
sensor. If voltmeter does not show about 5 volts, check wiring between
ECT sensor terminal No. 1 and ECM connector terminal A31 for a short
to ground.

[Buck380]

Still curious as to the outcome rombijr had...

Just a word about the ECT. If it fails, there will be multiple codes because engine coolant temp is one of the criteria your ECM uses to insure proper fuel mixture related to ambient temp. ECT failure results in what's called a "limp mode": fan on and default temp value of about 115 degrees. This basically means your car's going to run like crap. Since the computer uses the ECT to control the EGR, you're gunna get codes there, too. Your fuel mix gets outa whack once you're at op. temperature so you'll get a bunch of codes for that, too. Codes, codes codes.

So, the question remains: any codes rombijr? Use that downloadable shop manuel, buddy...

(Just wondering Tri; does that test procedure you excerpted require a "breakout box"?)

-Buck