Conditions for Clearing the MIL/DTC
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.
DTC P0643
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module (ECM) Connector End Views or Engine Controls Connector End Views |
||||
| 1 | Did you perform the Diagnostic System Check - Engine Controls? | - | Go to Step 2 | Go to Diagnostic System Check - Engine Controls |
| 2 |
|
4.7 V | Go to Step 3 | Go to Intermittent Conditions |
| 3 | Test each 5-volt reference 1 circuits for a short to voltage. Refer to Circuit Testing
and Wiring Repairs
in Wiring Systems. Did you find and correct the condition? |
- | Go to Step 6 | Go to Step 4 |
| 4 | Replace the ECM. Refer to Engine Control Module (ECM) Replacement
. Did you complete the replacement? |
- | Go to Step 6 | - |
| 5 |
|
- | Go to Step 2 | Go to Step 6 |
| 6 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? |
- | Go to Diagnostic Trouble Code (DTC) List | System OK |