oil temp sensor via can not reading correct

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oil temp sensor via can not reading correct

Postby Yves » Sat May 06, 2017 12:29 pm

I have an GM coolant temp sensor that I use as an oil temperature sensor and has it proprietary circuitry via a can board (iox). The thing worked well up untill recently. Now the readings are all over the place. The most noteworthy is that when putting ignition on, it seems to react like a WB sensor would but inversed. I mean, a reading of say 90°F for the first second or so, then a reading of 50°F for the next second and then it goes to -13°F.

Cannot find anything wrong with my setup.

Input appreciated.
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2017-05-06_20.53.26.msq
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Yves
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Re: oil temp sensor via can not reading correct

Postby racingmini_mtl » Sat May 06, 2017 1:04 pm

Have you checked the voltage at the sensor and at the IOx? That sounds like a bad physical connection for that sensor. It could be anywhere from the sensor to the input circuit itself.

Jean
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Re: oil temp sensor via can not reading correct

Postby Yves » Sat May 06, 2017 2:02 pm

at the sensor I have 4.97 V. At the IOX I have also around 5V.
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Re: oil temp sensor via can not reading correct

Postby racingmini_mtl » Sat May 06, 2017 2:09 pm

That's what you'd measure without any sensor connected. The 5V you see comes from the 5V pull up; the sensor would make this lower. Check your sensor return (ground) wiring.

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Re: oil temp sensor via can not reading correct

Postby Yves » Sat May 06, 2017 2:37 pm

racingmini_mtl wrote:That's what you'd measure without any sensor connected. The 5V you see comes from the 5V pull up; the sensor would make this lower. Check your sensor return (ground) wiring.

Jean


Jean, I measured voltage over the 2 wires going to the sensor. Wouldn't that confirm ground is ok ?
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Re: oil temp sensor via can not reading correct

Postby racingmini_mtl » Sat May 06, 2017 2:57 pm

That would mean the sensor has a very high resistance, possibly infinite. The latter would indicate a failed sensor. Disconnect the sensor and check its resistance.

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Re: oil temp sensor via can not reading correct

Postby Yves » Sun May 07, 2017 2:32 am

I checked the resistance over the sensor and I do have resistance here.

I then connected the pigtail of a iat sensor to the wiring and connected this to the circuit. The GM iat has the same resistance value, but the reaction on the gauge is the same : first a value of around 90°F then after a second 50°F and then it goes to -13°F. Looks to me something else is wrong.
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Re: oil temp sensor via can not reading correct

Postby racingmini_mtl » Sun May 07, 2017 9:12 am

One thing you could do is to connect a potentiometer in place of the sensor and check the ADC value on the IOx. If the ADC value moves as you move the pot and you see the same changes for the oil temp then the issue is the sensor or its connection. If the ADC value moves but you get the same thing for the oil temp you currently do, the issue is either a CAN transfer or a calibration issue. If the ADC value doesn't move, you have a problem with the IOx input circuit or the CPU.

If the issue seems to be on the IOx from the previous test, you will need to follow the voltage from the sensor (or pot) all the way to the CPU to see where the fault is.

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Re: oil temp sensor via can not reading correct

Postby Yves » Sun May 07, 2017 9:56 am

A potentiometer...Can't I just use the iat and use a hair dryer on it ? ADC values should then change.
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Re: oil temp sensor via can not reading correct

Postby racingmini_mtl » Sun May 07, 2017 9:59 am

As long as you can see the ADC value change. You could also measure how much the resistance changes to make sure it is significant.

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Re: oil temp sensor via can not reading correct

Postby racingmini_mtl » Sun May 07, 2017 10:00 am

I should add that one issue with that is that you don't eliminate the sensor from the test which would be useful.
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Re: oil temp sensor via can not reading correct

Postby Yves » Sun May 07, 2017 11:49 am

I did the following : put a raw signal gauge for the channel which is the oil temp on it. I then plugged in the ecu and let it do it's thing. The raw values exhibit the same behavior. first a lower value, then after a second an medium value and then a final high value.

However, when disconnecting the pigtail from the oil temp sensor, where it should change again, it didn't do anything. It just stayed at the last value (see previous paragraph).

Kinda strange that it started doing this after the last TS upgrade.
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Re: oil temp sensor via can not reading correct

Postby Yves » Sun May 07, 2017 11:55 am

I just tried something else. I changed the adp designations and used adp15 on channel 23/visa versa and set that as my oil temp sensor. Now it does work....raw value is solid as well. Temp reading is close to the CLT and IAT. :shock:
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Re: oil temp sensor via can not reading correct

Postby Yves » Mon May 08, 2017 8:45 am

any ideas ?
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Re: oil temp sensor via can not reading correct

Postby racingmini_mtl » Mon May 08, 2017 9:31 am

Can you post the entire project (not just the msq but the project backup containing both the MS3 and IOx)? Do this for both the version that works and the one where is doesn't. Make sure you don't include the datalogs and restore points in the backup (unselect the check boxes on the right).

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Re: oil temp sensor via can not reading correct

Postby Yves » Mon May 08, 2017 1:30 pm

even with everything unnecessary deleted it's still to big to post here. It only allows 716 kB.
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