Diagnostic Aids
The scan tool has the ability to command certain components and functions ON and OFF. If a component or function does not have this capability, operate the vehicle during its normal function criteria to inspect for an open or shorted circuit. An open or short to ground will appear in the open positions on the scan tool only when it is not commanded by the ECM or the scan tool. A short to voltage will appear in the short positions on the scan tool only while the component is being commanded by the ECM or scan tool.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Perform the Diagnostic System Check - Engine Controls. Is the check complete? |
Go to Step 2 | Go to Diagnostic System Check - Engine Controls |
| 2 | Install the scan tool. Is there a number 1=Fault below any of the numbered positions in the OUTPUT DRIVERS? |
Go to Step 3 | Go to Step 4 |
| 3 | Inspect for an open or shorted circuit in any corresponding position, or circuit, that contained a number 1 and repair, as necessary. Is a repair necessary? |
Go to Step 9 | Go to Step 7 |
| 4 | Command the output being inspected with a scan tool while watching the corresponding position for each circuit. Do any of the positions change to a 1? |
Go to Step 6 | Go to Step 5 |
| 5 | Command the output being inspected with a scan tool while watching the corresponding position for each circuit. Does the component or function operate when commanded? |
Go to Step 9 | Go to the appropriate component table for repair |
| 6 | Repair the short to voltage in the corresponding circuit for the position, or circuit, that displayed a 1. Is the repair complete? |
Go to Step 9 | - |
| 7 | Disconnect the electrical connector to the component connected to the fault circuit. Is a 1 still displayed in the corresponding OUTPUT DRIVER position? |
Go to Step 8 | Go to the appropriate component table for repair |
| 8 | Replace the engine control module (ECM). Refer to Engine Control Module Replacement
. Is the repair complete? |
Go to Step 9 | - |
| 9 | Operate the vehicle within the conditions under which the original symptom was noted. Does the system now operate correctly? |
System OK | Go to Step 2 |