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 MANUALSCHEVROLET1998SUBURBAN K2500, 7.4 J, PART TIMEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 24 (ENGINE CONTROLS - TESTS W/CODES - 6.5L)DIAGNOSTIC TROUBLE CODESDTC P0604 - CONTROL MODULE RANDOM ACCESS MEMORYDIAGNOSTIC PROCEDURES
1998 Chevrolet Suburban K2500, 7.4 J, Part Time
Diagnostic Procedures
1998 Chevrolet Suburban K2500, 7.4 J, Part TimeSECTION Diagnostic Procedures
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1997 GMC Yukon, 1997 GMC Suburban, 1997 GMC Pickup, 1997 GMC Cab & Chassis, and 1997 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
- Perform Powertrain ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING - 6.5L DIESEL article. Then go to next step.
- Check all PCM connections. Repair as necessary. After repairs, go to step 4). If connections are okay, go to next step.
- Replace PCM. After replacing PCM, go to next step.
- Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0604. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
- Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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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.