Hi Betty:DTC P1115 - Engine Coolant Temperature (ECT) Sensor Circuit Intermittent High Voltage
The Engine Coolant Temperature (ECT) sensor contains a semiconductor device which changes resistance based on temperature (a thermistor). The ECT sensor mounts in the left bank cylinder head near the front of the engine. The ECT sensor has a signal circuit and a ground circuit. The PCM applies a voltage (about 5.0 volts) on the signal circuit to the sensor. The PCM monitors changes in this voltage caused by changes in the resistance of the sensor in order to determine the engine coolant temperature.
When the engine coolant is cold, the sensor (thermistor) resistance is high, and the PCMs signal voltage is only pulled down a small amount through the sensor to ground. The PCM senses a high signal voltage (low temperature). When the engine coolant is warm, the sensor resistance is low, and the signal voltage is pulled down a greater amount. This causes the PCM to sense a low signal voltage (high temperature).
When the PCM senses a signal voltage higher than the normal operating range of the sensor, this DTC sets.
Zoom Image Link: boggs/DTC%20P1115_files/image002
Conditions for Setting the DTC
Engine operates longer than 60 seconds.
Conditions for Setting the DTC
The engine coolant temperature is less than -35 C degrees (-31 F) for less than a second.
Action Taken When the DTC Sets
The PCM stores the DTC information into memory when the diagnostic runs and fails.
The malfunction indicator lamp (MIL) will not illuminate.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.
Conditions for Clearing the DTC
A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.
Use a scan tool in order to clear the DTC.
Electromagnetic interference (EMI) can cause an intermittent DTC. Inspect the related circuits for being too close to secondary ignition wires and the generator.
If the engine sat overnight, the engine coolant temperature and intake air temperature values should display within a few degrees of each other. If the temperatures are not within 3 C degrees (5 F degrees), refer to Temperature vs Resistance .
For an intermittent, refer to Symptoms .
The numbers below refer to the step numbers on the diagnostic table.
If DTC P0118 failed this ignition, this indicates a hard failure is present. When a hard failure is present, both the hard and intermittent DTCs set.
When moving related connectors, visually/physically inspect connectors for the following:
Poor mating of the connector halves or a terminal not fully seated in the connector body (backed out).
Improperly formed or damaged terminals. Carefully reformed or replaced all connector terminals in the related circuits in order to insure proper terminal contact tension.
Poor terminal to wire connection. Inspect for poor crimps, crimping over wire insulation rather than the wire.
Dirt or corrosion on the terminals. Inspect the connector seals for being there and for being damaged.
When moving the related wiring harnesses, visually/physically inspect the wiring for the following:
Wire insulation that is rubbed through, causing an intermittent short.
Wiring broken inside the insulation.
Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents any damage to the harness connector terminals.
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