Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1344 (ENGINE CONTROL SYSTEM (DIAGNOSTIC INFORMATION & PROCEDURES) -- 1.8L (LNK))DIAGNOSTIC INFORMATION & PROCEDURESDIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLSTEST DESCRIPTION
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Test Description
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Test Description
WARNING: This page is about a different car, the 2004 Pontiac Vibe. 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.
- 2: Lack of communication may be due to a malfunction of the serial data circuit, the control module, or the scan tool. The specified procedures in Data Link Communications will determine the particular condition.
- 5:
This step stores the powertrain control module (PCM) DTC information into the scan tool memory. Review the captured information at the end of the diagnostic procedure in order to catch the next DTC in the event there are multiple DTCs stored. Use this information in order to determine how frequently and how recently the DTC set. This information and other operating conditions when the DTC set may help diagnose an intermittent condition. Capturing the stored information preserves data that the PCM loses when the following occurs:
- When you are instructed to clear the DTCs
- The PCM connectors are disconnected.
- The PCM is replaced during a diagnostic procedure or a repair procedure.
- 6:
A DTC P1600 that is stored must be diagnosed first. If multiple powertrain DTCs are stored, diagnose in the following order of priority:
- Component level DTCs-Sensors, solenoids, relays etc. Multiple DTCs within this category should be diagnosed in numerical order starting with the lowest numbered DTC, unless otherwise directed.
- System level DTCs-Misfire, fuel trim, catalyst etc.
- 7: This step is for vehicles that are located in areas that have an Inspection/Maintenance or emission testing program. The testing facility found one or more I/M system monitors has not run and passed.
Diagnostic System Check - Engine Controls
| Step | Action | Yes | No |
|---|---|---|---|
|
IMPORTANT:
|
|||
| 1 | Install a scan tool. Does the scan tool power-up? |
Go to Step 2 | Go to Scan Tool Does Not Power Up in Data Link Communications |
| 2 |
|
Go to Step 3 | Go to Scan Tool Does Not Communicate with VCM/PCM in Data Link Communications |
| 3 | Attempt to start the engine. Does the engine start and idle? |
Go to Step 4 | Go to Engine Cranks but Does Not Run |
| 4 | Select the DTC Information on the scan tool. Does the scan tool display any Powertrain DTCs? |
Go to Step 5 | Go to Step 7 |
| 5 | With the scan tool, save or capture the Powertrain DTC Information, Store Information. Did you complete the action? |
Go to Step 6 | - |
| 6 | Does the scan tool display DTC P0606? | Go to DTC P0601-P0607, P1600, P1621, P1627, P1680, P1681, P1683, or P2610 | Go to Diagnostic Trouble Code (DTC) List |
| 7 | Is the customer's concern with Inspection/Maintenance (I/M) testing? | Go to Inspection/Maintenance (I/M) System Check | Go to Step 8 |
| 8 | Perform the applicable symptom table:
Did you find and correct the condition? |
System OK | Go to Intermittent Conditions |
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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.