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NOTE: DO NOT perform this diagnostic if there is not a driveability concern, unless another procedure directs you to this diagnostic. Before proceeding with the diagnosis, search for applicable service bulletins. Unless a diagnostic procedure instructs you, DO NOT clear DTCs. If starting system condition exists, go to ENGINE ELECTRICAL SYSTEM DIAGNOSTIC SYSTEM CHECK . Ensure battery is fully charged. Ensure battery cables are clean and tight. Ensure PCM grounds are clean, tight, and in correct location.

Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC), located below steering column. Turn ignition switch to RUN position. If scan tool powers up, go to next step. If scan tool does not power up, go to TEST A: SCAN TOOL DOES NOT POWER UP under SYSTEM TESTS.
Using scan tool attempt to communicate with following modules:
- Vehicle Theft Deterrent module (VTD).
- Instrument Panel Cluster (IPC).
- Electronic Brake Control Module (EBCM).
- HVAC module.
If scan tool communicates with all specified modules, go to next step. If scan tool does not communicate with specified modules, see TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS.
Attempt to start engine. If engine starts and idles, go to next step. If engine does not start, diagnose no start by symptom. Go to TROUBLESHOOTING - NO CODES - TRUCKS article in ENGINE PERFORMANCE.
Select DISPLAY DTCs from PCM, VTD, EBCM, IPC, and HVAC modules. If any DTCs are retrieved, go to next step. If no DTCs are retrieved, go to step 9 .
Select CAPTURED INFO to store DTCs in memory, then go to next step.
If scan tool does not display any DTCs which begin with "U", go to next step. If scan tool displays DTCs which begin with "U", see TEST B: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE under SYSTEM TESTS.
If scan tool displays DTC P0601, P0602 or P0604, go to next step. If scan tool does not display DTC P0601, P0602 or P0604, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
If scan tool displays DTC P0562, P0563, P01637 or P1638, go to ENGINE ELECTRICAL SYSTEM DIAGNOSTIC SYSTEM CHECK . If scan tool does not display DTC P0562, P0563, P01637 or P1638, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
If customer's concern is with automatic transmission, see AUTOMATIC TRANSMISSION DIAGNOSTIC SYSTEM CHECK . See TROUBLESHOOTING - NO CODES - TRUCKS article in ENGINE PERFORMANCE. Repair as necessary.
If customer's concern is not with inspection and maintenance testing, go to next step. If customer's concern is with inspection and maintenance testing, go to INSPECTION & MAINTENANCE DIAGNOSTIC SYSTEM CHECK .
Diagnose engine control system by symptom. See appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE. If concern still exists, diagnose intermittent condition. See PROBLEM DIAGNOSIS under INTERMITTENTS.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Engine Controls Diagnostic System Check

Use the Manual With the Right Hardware

When to See a Mechanic

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