Circuit Description
The Engine Coolant Temperature (ECT) sensor contains a device which changes the resistance that is based on temperature (a thermistor). The ECT sensor is located in the coolant crossover pipe at the center rear of the engine. The ECT sensor has a signal circuit and a ground circuit. The ECM applies a voltage (about 5.0 volts) on the signal circuit to the sensor. The ECM monitors the changes in this voltage that are caused by the 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. Therefore, the ECM will sense a high signal voltage (low temperature). When the engine coolant is warm, the sensor resistance is low. This causes the ECM to sense a low signal voltage (high temperature).
When the ECM senses a signal voltage outside of the normal operating range of the sensor, this DTC will set.
Conditions for Running the DTC
DTC P0110 not set
Conditions for Setting the DTC
| • | The ECT signal voltage indicates an ECT that is greater than 139°C (282°F) |
| OR |
| • | The ECT signal voltage indicates an ECT that is less than -43°C (-45°F). |
| • | The above condition is met for at least 2.0 seconds. |
Action Taken When the DTC Sets
The ECM illuminates the malfunction indicator lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.
Conditions for Clearing the MIL/DTC
| • | The ECM turns OFF the MIL after three consecutive drive trips that the diagnostic runs and passes. |
| • | A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic. |
| • | The ECM battery voltage is interrupted. |
| • | The scan tool clears the MIL/DTC. |
Diagnostic Aids
Use the Connector Test Adapter Kit J 35616 for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.
Check the following conditions:
| • | Poor connections at the ECM or at the component. Inspect the harness connectors for the following: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal to wire connection. |
| - | Refer to Engine Control Module Diagnosis Checking Terminal Contact for the proper procedure. |
| • | Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving any of the related connectors and the wiring harnesses. A change in the display may help in order to locate the fault. |
| If the sensor signal is only affected when the harness is moved at a component, and there is no problem with the harness or the connections, the component may be damaged. |
| • | When checking the ECT sensor, the Temperature vs Resistance may be used in order to test the sensor at various temperature levels in order to evaluate the possibility of a shifted (mis-scaled) sensor. A shifted sensor could result in poor driveability complaints. |
| Refer to Symptoms , Preliminary Checks, for the intermittents. |
| • | If other DTCs are set that share the same ground circuit, check the point where the circuits ground to the chassis or the engine block. |
If the engine has been allowed to sit overnight, the engine coolant temperature and the engine intake air temperature values should display within a few degrees of each other. If the temperatures are not within 3°C (5°F), refer to Temperature vs Resistance
Test Description
The number(s) below refer to the step numbers on the diagnostic table.
-
The scan tool will show the default value after the DTC Poll 5 sets.
-
Determine if the circuit is currently malfunctioning.
-
Using the Freeze Frame data may aid in locating an intermittent condition. If the DTC cannot be duplicated, review the information in the Freeze Frame. Try to operate the vehicle within the same freeze frame conditions (the RPM, the MAF, the vehicle speed, the temperature etc.) that were noted. This process may help to recreate the malfunction.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Is the ECT above the specified value? | 139°C (282°F) | |||
Is the ECT below the specified value? | -43°C (-45°F) | |||
4 |
Is the ECT value affected by moving the harness or connectors? | -- | ||
Is this DTC set? | -- | Refer to Diagnostic Aids | ||
6 |
Is the ECT below the specified value? | -43°C (-45°F) | ||
7 |
Is continuity indicated? | -- | ||
8 |
Is the ECT above the specified value? | 139°C (282°F) | ||
9 | Jumper the ECT signal circuit to a known good ground. Is the ECT above the specified value? | 139°C (282°F) | ||
10 |
Is continuity indicated? | -- | ||
11 |
Is continuity indicated? | -- | ||
12 | Repair the harness/connections as necessary. Refer to Test Description. Is the action complete? | -- | -- | |
13 | Repair the signal circuit shorted to ground. Is the action complete? | -- | -- | |
14 | Repair the open/high resistance signal circuit. Is the action complete? | -- | -- | |
15 | Repair the open/high resistance ground circuit. Is the action complete? | -- | -- | |
16 | Check for a poor connection or poor terminal tension at the ECT sensor harness connector. Refer to Electrical Diagnosis in Engine Electrical, and Troubleshooting Procedures for the proper procedure. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis . Was a problem found and corrected? | -- | ||
17 | Replace the ECT sensor. Refer to Engine Coolant Temperature Sensor Replacement . Is the action complete? | -- | -- | |
18 | Check for a poor connection or poor terminal tension at the ECM harness connector. Refer to Electrical Diagnosis in Engine Electrical, and Troubleshooting Procedures for the proper procedure. Also, refer to Checking Terminal Contact in Engine Control Module Diagnosis . Was a problem found and corrected? | -- | ||
19 |
Important: This vehicle is equipped with a Theft Deterrent System which interfaces with the Engine Control Module (ECM). Program the new ECM with the frequency code of the theft deterrent module that is currently on the vehicle. Replace the ECM. Refer to Engine Control Module Replacement/Programming . Is the action complete? | -- | -- | |
20 |
Is this DTC set? | -- | ||
21 | Were there any additional DTCs noted during the Powertrain OBD System Check that have not been diagnosed? | -- | Go to the applicable DTC table | The System is OK |
