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A little help with a Thermistor FIXED
- Paul74
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8 years 3 weeks ago - 8 years 3 weeks ago #13042
by Paul74
A little help with a Thermistor FIXED was created by Paul74
Having some trouble with a thermistor. 2010 Bluebird D3 with a Cummins ISB6.7 CM2150 Fault code1878 Aftertreatment Exhaust Gas Temperature 3 - Data Erratic, Intermittent, or Incorrect. The aftertreatment diesel particulate filter outlet temperature sensor is not changing with engine operating conditions.
I can watch the voltage change with the factory scan tool on all 3 thermistors. Factory scan tool appears to be using thermistor #2 temp as a substituted value for thermistor #3. Did the unplug it test scan tool went to 5 volts on the signal for thermistor 3 and set a code for shorted to high source. Shorted the signal and return together for thermistor 3 scan tool showed 0 volts, and threw a code for shorted to low source. At this point in time I replaced the thermistor. Problem was not fixed. Checked resistance of all 3 thermistors at ECM connector and at each thermistor. All 3 thermistors are within 2kohms of each other and within spec for the temperature at the ECM and at the sensor according to Factory chart. Checked all 3 signal wires for short to ground OL MOhms. Removed harness from loom and visually inspected it. I didn't find any damage. Sensor 1 and 3 are identical and are interchangeable. Swapped sensor 1 and 3 no change.
Does anyone have any other ideas? I am about ready to put an ECM in this pig.
I can watch the voltage change with the factory scan tool on all 3 thermistors. Factory scan tool appears to be using thermistor #2 temp as a substituted value for thermistor #3. Did the unplug it test scan tool went to 5 volts on the signal for thermistor 3 and set a code for shorted to high source. Shorted the signal and return together for thermistor 3 scan tool showed 0 volts, and threw a code for shorted to low source. At this point in time I replaced the thermistor. Problem was not fixed. Checked resistance of all 3 thermistors at ECM connector and at each thermistor. All 3 thermistors are within 2kohms of each other and within spec for the temperature at the ECM and at the sensor according to Factory chart. Checked all 3 signal wires for short to ground OL MOhms. Removed harness from loom and visually inspected it. I didn't find any damage. Sensor 1 and 3 are identical and are interchangeable. Swapped sensor 1 and 3 no change.
Does anyone have any other ideas? I am about ready to put an ECM in this pig.
Last edit: 8 years 3 weeks ago by Paul74.
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