Circuit Description
The PCM monitors the EGR valve pintle position input to ensure that the valve responds properly to commands from the PCM and to detect a fault if the pintle position sensor circuit is open or shorted. If the PCM detects an excessively low EGR Feedback signal voltage, DTC P0405 will set.
Conditions for Running the DTC
System voltage is more than 10 volts.
Conditions for Setting the DTC
| • | EGR Feedback is less than 0.14 volt at any time. |
| • | The condition is present for more than 20 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using a scan tool. |
Diagnostic Aids
| • | Poor connection at PCM or EGR Valve. |
| Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness. |
| Inspect the wiring harness for damage. If the harness appears to be OK, connect J 39200 DMM and check circuit continuity while moving connectors and wiring harnesses related to the EGR valve. A change in the DMM display will indicate the location of the malfunction. |
Test Description
The numbers below refer to the step numbers on the diagnoatic table.
-
Verifies that the malfunction is present.
-
If DTC P0405 will only set under certain conditions, the malfunction may be intermittent; refer to Diagnostic Aids. If an intermittent wiring problem is not present, check for a poor connection at the PCM or the EGR valve.
-
This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check ? | -- | ||||||||
|
Important: If DTC P1635 5 Volt Reference Circuit is set, perform that diagnostic first.
Does the desired EGR position remain within 15 percent of actual EGR position at all commanded positions? | -- | |||||||||
Does the scan tool indicate DTC P0405 failed this ignition? | -- | Go to Diagnostic Aids | ||||||||
4 |
Is the voltage at the specified value? | 5V | ||||||||
5 | Probe the EGR valve pintle position signal circuit at the EGR valve harness connector with a test lamp connected to B+. Is the test lamp ON? | -- | ||||||||
6 |
Is actual EGR position at the specified value? | 100 percent | ||||||||
7 |
Was a problem found? | -- | ||||||||
8 |
Is the test lamp ON? | -- | ||||||||
9 | Probe the 5 volt reference A circuit with a test lamp to B+. Is the test lamp ON? | -- | ||||||||
10 |
Is the test lamp ON? | -- | ||||||||
11 |
Was a problem found? | -- | ||||||||
12 | Locate and correct the short to ground in the EGR valve pintle position signal circuit. Refer to Wiring Repairs in Wiring Systems. Is action complete? | -- | -- | |||||||
13 |
Was a problem found? | -- | ||||||||
14 | Replace the EGR valve. Refer to Exhaust Gas Recirculation Valve Replacement . Important: If the EGR valve shows signs of excessive heat, check the exhaust system
for blockage (possibly a plugged converter) using the procedure found in the
Restricted Exhaust System Check
. If the exhaust
system is restricted, repair the cause; one of which might be an injector
which is open due to one of the following reasons:
Is action complete? | -- | -- | |||||||
15 |
Was a problem found? | -- | ||||||||
16 | Locate and repair short to ground in the 5 volt reference A circuit. Refer to Wiring Repairs in Wiring Systems. Is action complete? | -- | -- | |||||||
17 |
Was a problem found? | -- | ||||||||
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is action complete? | -- | -- | ||||||||
19 |
Does the scan tool indicate DTC P0405 failed this ignition? | -- | System OK |
