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.
Powertrain Control Module (PCM)
The PCM is on the CAN. The PCM controls the engine for better fuel economy, emissions control, failure mode detection and storage. If one of the communications network circuits become shorted to ground or voltage, or if some but not all termination resistors are lost, communications can continue. Check the communications network circuits 1827 (WH/LG) and 1828 (PK/LG) between the PCM C175 (gasoline) or PCM C176a (diesel) and the DLC C251. The total resistance values must not be more than 5 ohms. If the resistance is more than 5 ohms there is an open circuit in the CAN, damage to the DLC C251, damage to the PCM C175 (gasoline), damage to the PCM C176a (diesel) or a problem in the in-line connector. For additional information, See INTRODUCTION - GASOLINE and/or INTRODUCTION -- 6.0L DIESEL articles.
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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.
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