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ECT Sensor problem

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Old 12-07-2010, 06:00 PM   #1
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Default ECT Sensor problem

I Installed a new ECT sensor on my camaro beacuse my guage was not reading a temp. The actual guage its sellf works beacuse when i turn the car on and off it moves. But when the car is running the guage will not work. I looked on all data and ran through all the test they asked me to. When i use the snap on modis and jump the wires the temp goes from -38 to 238 like its suspose to. So the wiring is good and the the cars computer is reading it. So the wiring and the computer and the sensor are not bad. My buddy has the same year camaro as me i took his ECT sensor out and put it in my car and it still didnt work. I also put mine on his and it did work. So it something to do with my car. The wiring is good the sensor is good and and Cars ECU is good. Has anyone else had this proble or know what is wrong?
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Old 12-07-2010, 07:35 PM   #2
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its most likely your cluster because if the scanner shows the right temperature there is no reason for the guage to be off other than a bad guage. the data going to the scanner is the same going to the cluster, is daisy chained. air bag module, body control module. diagnostic plug. etc..
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Old 12-07-2010, 08:10 PM   #3
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its not the guage beacuse the snap on modis reads -38 all the time unless u jump the wire and the it goes up to 238. so its not a cluster related proble beacuse the guage actually works. the ECU is not reading the ect until u jump the wires. The Snapon modis scan tool never reads a temp. until u jump the wires and then it reads 238
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Old 12-12-2010, 03:54 PM   #4
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Quote:
Originally Posted by 98z28darkhell View Post
its not the guage beacuse the snap on modis reads -38 all the time unless u jump the wire and the it goes up to 238. so its not a cluster related proble beacuse the guage actually works. the ECU is not reading the ect until u jump the wires. The Snapon modis scan tool never reads a temp. until u jump the wires and then it reads 238
That was confusing to me.
With the wires connected to your ECT sensor, you're saying that scanning the PCM never reads a real temperature?
Assuming the wires plugged to the ECT, your scanner says -38*F.
Assuming the wires unplugged from the ECT, your scanner says -38*FF.

Is this correct?

How exactly are you jumping the wires? is it at the plug where they contact the ECT sensor? Is this a 2-wire sensor plug?

-38*F reading shows an open circuit.
That can mean that the plug is defective and not contacting the sensor.

If your PCM scanner shows a real temp, but gauge doesn't work, then you either have a faulty gauge circuit, or the gauge gets its signal from a second ECT sensor.

I have seen cars with:
One one-wire sensor
One two-wire sensor
Two two-wire sensors
One three-wire sensor
One sensor for the PCM and one sensor for the gauge
and a few other variations of one-wire sensors in cases where the ECM/PCM takes ground through the engine (older cars).

By the way, the power-on gauge sweep function is a separate circuit from the ECT signal, and is common to all (or most) of your gauges.
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Old 12-13-2010, 05:08 PM   #5
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its a 3 wire sensor. the ECM in not getting a temp at all. It reads -38 with the ect pluged in or unplugged.
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Old 12-13-2010, 07:12 PM   #6
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its a 3 wire sensor. the ECM in not getting a temp at all. It reads -38 with the ect pluged in or unplugged.
You said your sensor worked fine on a friend's car, that I'll assume has the same three-wire plug for the sensor as you do.

You didn't say which two wires you bridged (out of the three) during your test, so I still cannot be sure at this point.
I can tell you that one of the wires is for the gauge, and probably does not show up on a data scanner. If your wiring is good as you have concluded, then I'd assume that your PCM is seeing correct temperature from the ECT sensor, thus allowing your car to run normally, even though your gauge doesn't work.
You can verify that your PCM is seeing correct temp by observing a data scanner while your car is running.

That leaves the gauge circuit to be defective, - possibly just a loose connection at the cluster harness, or gauge itself.
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Old 12-14-2010, 04:48 PM   #7
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well the scanner is reading -38 temp. the pcm is reading -38. the 2 wires i jump were the wires that go 2 the pcm and the guage i beleive. thoses are the 2 wires ALLDATA told me to jump.
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Old 12-14-2010, 04:48 PM
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