Test Description
WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The numbers below refer to the step numbers on the diagnostic table.
- 7: This step verifies that the PCM is providing ground to the AIR valve relay when the command is ON. Listen for a click when the relay operates. Be sure to command the AIR valve relay ON and the OFF. Repeat the commands as necessary.
- 8: This step tests if a ground is constantly being applied to the AIR valve relay.
- 9: This step tests for a short to voltage on the AIR valve relay control circuit. This will allow the AIR solenoid to hold the shut-off valve open continuously with the key in the OFF position.
- 10: This step tests for a short to ground on the AIR valve relay control circuit. This will allow the AIR valve to hold the shut-off valve open continuously with the key in the ON position.
DTC P0412 (L26, NU3)
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Component Views or Engine Controls Connector End Views |
||||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | - | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Inspect the fuse for the AIR relays. Is the fuse open? |
- | Go to Step 6 | Go to Step 3 |
| 3 |
|
- | Go to Step 4 | Go to Testing for Intermittent Conditions and Poor Connections |
| 4 |
|
- | Go to Step 5 | Go to Step 13 |
| 5 |
|
70-90 Ω | Go to Step 7 | Go to Step 14 |
| 6 |
IMPORTANT:
The ignition 1 voltage circuit of the AIR valve relay is spliced to other components of the vehicle. Test all circuits and components that are supplied by the fuse for the AIR relay for excessive current draw. Refer to Circuit Testing
and Wiring Repairs
.Did you find and correct the condition? |
- | Go to Step 16 | Go to Testing for Intermittent Conditions and Poor Connections |
| 7 |
|
- | Go to Step 11 | Go to Step 8 |
| 8 | Does the test lamp remain illuminated with each command? | - | Go to Step 10 | Go to Step 9 |
| 9 | Test the AIR valve relay control circuit for an open or a short to voltage. Refer to Circuit Testing
and Wiring Repairs
. Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 12 |
| 10 | Test the AIR valve relay control circuit for a short to ground. Refer to Circuit Testing
and Wiring Repairs
. Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 12 |
| 11 | Test for a poor or intermittent connection at the AIR valve relay. Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
. Did you find a condition? |
- | Go to Step 16 | Go to Step 14 |
| 12 | Test for shorted terminals and for poor connections at the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections
and Connector Repairs
. Did you find and correct the condition? |
- | Go to Step 16 | Go to Step 15 |
| 13 | Repair the open or high resistance in the AIR valve relay ignition 1 voltage circuit. Refer to Wiring Repairs
. Did you complete the repair? |
- | Go to Step 16 | - |
| 14 | Replace the AIR valve relay. Refer to Relay Replacement (Within an Electrical Center)
or Relay Replacement (Attached to Wire Harness)
. Did you complete the replacement? |
- | Go to Step 16 | - |
| 15 | Replace the PCM. Refer to Control Module References
for replacement, setup and programming. Did you complete the replacement? |
- | Go to Step 16 | - |
| 16 |
|
- | Go to Step 2 | Go to Step 17 |
| 17 | Observe the Capture Info with a scan tool. Are there any DTCs that you have not diagnosed? |
- | Go to Diagnostic Trouble Code (DTC) List - Vehicle | System OK |