Circuit Description
The VCM constantly monitors the linear EGR valve pintle position sensor in order to ensure that the valve is responding properly to the commands from the VCM. The DTC P1406 is a type A DTC.
Conditions for Setting the DTC
| • | The ignition voltage is greater than 9 volts |
| • | The difference between the actual EGR position and the desired EGR position is greater than 10% for 10 seconds. |
Action Taken When DTC Sets
If a current DTC P1406 sets during 2 consecutive test cycles, the VCM turns ON the MIL.
Conditions for Clearing the MIL/DTC
The VCM turns OFF the MIL after 3 consecutive driving trips without a fault condition present. A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (the coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the engine coolant temperature exceeds 71°C (160°F) during that same ignition cycle) or the scan tool clearing feature has been used.
Diagnostic Aids
A poor connection or a rubbed-through wire insulation may cause an intermittent condition. Check for the following conditions:
| • | A poor connection or a damaged harness - Inspect VCM harness connectors for backed out terminals BLK 18, GRY 27, GRY19, or RED 10 for the following items: |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed or damaged terminals |
| • | A poor terminal to wire connection |
| • | A damaged harness |
Intermittent test - If the connections and the harness check OK, monitor a digital voltmeter connected between the affected terminals and the ground while moving the related connectors and the wiring harness. If the failure is induced, the voltage reading will change.
Test Description
The numbers below refer to the step umbers on the diagnostic table.
-
Checks for an EGR valve sticking partially open or an incorrect pintle position sensor feedback signal.
-
Ensures that the VCM is capable of controlling EGR pintle position and is reading the pintle position feedback signal properly.
-
Checks the EGR valve driver in the VCM and the EGR LOW signal circuit.
-
The checks for an incorrect EGR pintle position sensor input signal. This test verifies a 5 volt reference at the EGR valve.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear Info function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
Does the scan tool display the specified value? | 0% | |||
Does the Actual EGR position reflect the Desired EGR position? | -- | Go to Diagnostic Aids | ||
Is the test light on? | -- | |||
Is the test light on? | -- | |||
6 |
Was a problem found? | -- | ||
7 | Repair the poor connections or open in the EGR Low circuit as necessary. Refer to Wiring Repair in Engine Electrical. Is the action complete? | -- | -- | |
8 |
Is the display at the specified value? | 0% | ||
9 | Is the DTC P0108 also set? | -- | Go to DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage | |
10 | Check for a short to voltage in the EGR pintle position circuit. Was a problem found? | -- | ||
11 | Repair the short to voltage in the EGR pintle position circuit. Refer to Wiring Repair in Engine Electrical. Is the action complete? | -- | -- | |
12 | Check for a blown fuse number 4. Was fuse number 4 blown? | -- | ||
13 | Replace fuse number 4. Is the action complete? | -- | -- | |
14 | Repair the short to ground in the EGR high circuit. Refer to Wiring Repair in Engine electrical. Is the action complete? | -- | -- | |
15 | Repair the open EGR high circuit. Refer to Wiring Repair in Engine Electrical. Is the action complete? | -- | -- | |
16 |
Is the test light on? | -- | ||
17 | Check for an open EGR pintle position ground circuit. Was a problem found? | -- | ||
18 | Repair the open in the EGR pintle position ground circuit. Refer to Wiring Repairs in Engine Electrical. Is the action complete? | -- | -- | |
19 |
Is the test light on? | -- | ||
20 |
Is the test light on? | -- | Go to Step 21 | Go to Step 39 |
21 | Check for short to ground in the EGR low circuit. Was a problem found? | -- | ||
22 | Repair the short circuit to ground in the EGR low circuit. Refer to Wiring Repair in Engine Electrical. Is the action complete? | -- | -- | |
23 | Check for a poor connection at the EGR valve harness connector. Was a problem found? | -- | ||
24 | Repair the poor connection at the EGR valve harness connector. Refer to Wiring Repair in Engine Electrical. Is the action complete? | -- | -- | |
25 | Replace the EGR valve. Refer to EGR Valve Replacement . Is the action complete? | -- | -- | |
26 | Connect a DVM between the EGR valve connector terminal B and D. Is the voltage approximately at the specified value? | 5.0V | ||
27 | Connect a DVM between the VCM harness connector terminal 5V Reference circuit and ground. Is the voltage at the specified value? | 5.0V | ||
28 | Check for a poor connection at the VCM harness connector terminal for the 5V Reference circuit. Was a problem found? | -- | ||
29 | Repair the poor connection at the VCM harness connector terminal 5V Reference circuit. Refer to Wiring Repair in Engine Electrical. Is the action complete? | -- | -- | |
30 | Repair the open EGR pintle position 5 volt reference. Refer to Wiring Repair in Engine Electrical. Is the action complete? | -- | -- | |
31 |
Is the test light on? | -- | ||
32 | Check for a short to ground in the EGR pintle position circuit. Was a problem found? | -- | ||
33 | Repair the short to ground in the EGR pintle position circuit. Refer to Wiring Repair in Engine electrical. Is the action complete? | -- | -- | |
34 |
Is the voltage within the specified value? | 3.5-5.0V | ||
35 |
Was a problem found? | -- | ||
36 | Check for a poor connection at the VCM harness connector terminal Pintle Position circuit. Was a problem found? | -- | ||
37 | Repair the open in the EGR pintle position circuit. Refer to Wiring Repair in Engine Electrical. Is the action complete? | -- | -- | |
38 | Repair the connection at the VCM harness connector terminal Pintle Position circuit. Refer to Wiring Repair in Engine Electrical. Is the action complete? | -- | -- | |
39 | Replace the VCM. Important: When replacing the VCM, the new VCM will need to be programmed. Refer to VCM Replacement/Programming . Is the action complete? | -- | -- | |
40 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
41 | Use the scan tool in order to display the Capture Info and the Review Info. Are there any DTCs displayed that have not been diagnosed? | -- | Go to the applicable DTC table | System OK |
