Circuit Description
The engine control module (ECM) monitors various sensors to determine engine operating conditions. The ECM controls fuel delivery, spark advance, transaxle operation, and emission control device operation based on the sensor inputs.
The ECM provides a sensor ground to all of the sensors. The ECM applies 5 volts through a pull-up resistor and monitors the voltage present between the sensor and the resistor to determine the status of the engine coolant temperature (ECT) sensor and the intake air temperature (IAT) sensor. The ECM provides the exhaust gas recirculation (EGR) pintle position sensor, the throttle position (TP) sensor, the manifold absolute pressure (MAP) sensor, and the fuel tank pressure sensor with a 5-volt reference and a sensor ground signal. The ECM monitors the separate feedback signals from these sensors to determine their operating status.
Diagnostic Aids
Be sure to inspect the ECM and the engine grounds for being secure and clean.
A short to voltage in one of the sensor circuits can cause one or more of the following DTCs to be set: P0108, P0113, P0118, P0123, P0132, P0463, P0533, P1106, P1111, P1115, and P1121.
If a sensor input circuit has been shorted to voltage, ensure that the sensor is not damaged. A damaged sensor will continue to indicate a high or low voltage after the affected circuit has been repaired. If the sensor has been damaged, replace it.
An open in the sensor ground circuit between the ECM and the splice will cause one or more of the following DTCs to be set: P0107, P0108, P0113, P0118, P0122, P0123, P0131, P0137, P0462, P0532, P1106, P1111, P1115, and P1121.
A short to ground in the 5-volt reference circuit or an open in the 5-volt reference circuit between the ECM and the splice will cause one or more of the following DTCs to be set: P0107, P0112, P0117, P0122, P0131, P0137, P0462, P0532, P1107, P1112, P1114, and P1122.
Check for the following conditions:
| • | Inspect for a poor connection at the ECM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection. |
| • | Inspect the wiring harness for damage. If the harness appears to be OK, observe an affected sensor displayed value on the scan tool with the ignition ON and the engine OFF while moving connectors and wiring harnesses related to the affected sensors. A change in the affected sensor displayed value will indicate the location of the fault. |
| • | If a sensor input circuit has been shorted to voltage, ensure that the sensor has not been damaged. A damaged IAT or ECT sensor will continue to indicate a high voltage or low temperature after the affected circuit has been repaired. A damaged ACT, TP, MAP, fuel tank pressure, or EGR pintle position sensor will indicate a high or low voltage or may be stuck at a fixed value after the affected circuit has been repaired. If the sensor has been damaged, replace it. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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The On-Board Diagnostic (EOBD) System Check prompts the technician to complete some basic checks and store the Freeze Frame and Failure Records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
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A faulty EGR valve can leak a small amount of current from the ignition feed circuit to the 5-volt reference circuit. If the problem does not exist with the EGR valve disconnected, replace the EGR valve.
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The replacement ECM must be reprogrammed. Refer to the latest Techline procedure for ECM reprogramming.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Perform an On-Board Diagnostic (EOBD) System Check. Is the check complete? | -- | Go to Step 2 | ||||||
2 |
Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 3 | ||||
3 |
Did you find and correct the condition? | -- | Go to Step 19 | Go to Step 4 | ||||
4 | Measure the voltage of the exhaust gas recirculation (EGR) pintle position sensor signal circuit between ECM harness connector and ground. Is the voltage near the specified value? | 0 V | Go to Step 5 | Go to Step 9 | ||||
5 | Measure the voltage of the manifold absolute pressure (MAP) sensor signal circuit between the ECM harness connector and ground. Is the voltage near the specified value? | 0 V | Go to Step 6 | Go to Step 12 | ||||
6 | Measure the voltage of the throttle position (TP) sensor signal circuit between the ECM harness connector and ground. Is the voltage near the specified value? | 0 V | Go to Step 7 | Go to Step 12 | ||||
7 | Measure the voltage of the intake air temperature (IAT) sensor signal circuit between the ECM harness connector and ground. Is the voltage near the specified value? | 0 V | Go to Step 8 | Go to Step 13 | ||||
8 | Measure the voltage of the engine coolant temperature (ECT) sensor signal circuit between the ECM harness connector and ground. Is the voltage near the specified value? | 0 V | Go to Step 16 | Go to Step 14 | ||||
Is the voltage near the specified value? | 0 V | Go to Step 10 | Go to Step 15 | |||||
10 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- | ||||
11 | Locate and repair the short to voltage in the MAP sensor signal circuit. Did you complete the repair? | -- | Go to Step 19 | -- | ||||
12 | Locate and repair the short to voltage in the TP sensor signal circuit. Did you complete the repair? | -- | Go to Step 19 | -- | ||||
13 | Locate and repair the short to voltage in the IAT sensor signal circuit. Did you complete the repair? | -- | Go to Step 19 | -- | ||||
14 | Locate and repair the short to voltage in the ECT sensor signal circuit. Did you complete the repair? | -- | Go to Step 19 | -- | ||||
15 | Locate and repair the short to voltage in the EGR pintle position sensor circuit. Did you complete the repair? | -- | Go to Step 19 | -- | ||||
16 | Measure the voltage of the fuel tank pressure sensor signal circuit between the ECM harness connector and ground. Is the voltage near the specified value? | 0 V | Go to Step 18 | Go to Step 17 | ||||
17 | Locate and repair the short to voltage in the fuel tank pressure sensor signal circuit. Did you complete the repair? | -- | Go to Step 19 | -- | ||||
Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 19 | -- | |||||
19 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | Go to Step 20 | Go to Step 2 | ||||
20 | Are any DTCs displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK |
