1998 GMC Forward Control 6.5 FFACTORY OEM SERVICE PROCEDURE

TDC Offset Learn Procedure (6.5L Diesel)

PCM will automatically activate TDC offset program when engine coolant is greater than 170Β°F (77Β°C) and engine speed is 900 RPM or less. A momentary engine stumble will occur once engine has reached desired temperature and RPM. This is an indication that PCM auto learn function has been activated. If offset is programmed out of range, DTC P1214 will set.

Factory Service Tools

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When to See a Mechanic

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

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.