Circuit Description
This diagnostic tests for an EGR valve that is stuck open. The PCM determines that the EGR valve is stuck open if the actual EGR position and the learned closed EGR position vary by more than a predetermined value. The PCM tests for a stuck valve when the desired EGR position is at 0%. The PCM commands the EGR valve to 100% during certain driving conditions in order to clear a possible restriction from the EGR valve if the PCM determines that the valve is stuck open. The PCM retests for a stuck valve when the desired EGR position returns to 0%. A failure timer increments if the stuck EGR valve condition is still present. This DTC sets when the timer reaches a predetermined value.
Conditions for Running the DTC
The ignition voltage is greater than 11.7 volts.
Conditions for Setting the DTC
The actual EGR pintle position is greater than 0.29 volts when the valve is commanded closed.
Action Taken When the DTC Sets
The PCM disables the EGR valve for the ignition cycle.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Use a scan tool in order to clear the MIL and the DTC. |
Diagnostic Aids
Important: The PCM terminals C1-24 and C2-24 are the Sensor Ground Jumper terminals. This DTC sets if the jumper is open or the connection between the jumper and the PCM is faulty. Inspect for proper terminal tension/connections at the PCM harness connector before replacing the PCM.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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If DTC P1635 sets at the same time, this indicates that the 5.0 volt reference circuit is either shorted to a ground or shorted to a voltage. The 5.0 volt reference circuit is internally connected within the PCM.
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This step tests for open EGR valve when the valve should be closed.
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This step tests for an EGR pintle position voltage that is out of range. The EGR pintle position voltage should be between 0.14 and 1.07 volts at idle.
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Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicated 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 vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For an intermittent condition, refer to Symptoms
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This tests whether the ground circuit is available to the EGR valve. Test for poor electrical connections at the EGR valve. Refer to Repairing Connector Terminals in Wiring Systems.
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The PCM terminals C1-24 and C2-24 are the Sensor Ground Jumper terminals. This DTC sets if the jumper is open or the connection between the jumper and the PCM is faulty.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
Did DTC P1635 fail this ignition? | -- | |||
Idle the engine. Is the idle quality poor? | -- | |||
4 |
Does the idle quality return to normal? | -- | ||
Is the EGR pintle position voltage within the specified value? | 0.14-1.07V | |||
Does the scan tool indicate that this diagnostic failed this ignition? | -- | Go to Diagnostic Aids | ||
7 |
Is the EGR pintle position voltage below the specified value? | 0.14V | ||
Probe the EGR pintle position ground circuit at the EGR valve harness connector with the test lampJ 35616-200 connected to B+. Refer to Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate? | -- | |||
9 | Measure the voltage at the 5.0 volt reference circuit to ground using the DMM J 39200 . Is the voltage greater than the specified value? | 5.0V | ||
10 |
Did you find and correct the condition? | -- | ||
11 |
Did you find and correct the condition? | -- | ||
12 |
Did you find and correct the condition? | -- | ||
13 |
Did you find and correct the condition? | -- | ||
14 | Repair the 5.0 volt reference circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |
15 |
Did you find and correct the condition? | -- | ||
16 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Is the action complete? | -- | -- | |
|
Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | -- | ||
18 |
Does the scan tool indicate that this test ran and passed? | -- | ||
19 | Select the Capture Info option and the Review Info using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
