PTO Components: Pcm: Notes
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The powertrain control module (PCM) is the control center of the PTO system. Applications with a 6.6L diesel use an ECM. The PCM monitors numerous engine and vehicle functions. To engage the PTO, the PCM must see the following conditions:
- PTO switch is ON
- Engine must be running
- Transmission must be in PARK or NEUTRAL
- Park Brake must be set for manual transmission only
- Vehicle speed must be zero in Preset Mode only
- Brake or Clutch must not be depressed
The PCM constantly looks at the information from various sensors and other inputs, and controls the systems that affect vehicle performance. The PCM also performs a diagnostic test on the Electronic Throttle Control system.