TDC Offset Learn Procedure
WARNING: This page does not describe the selected car, but rather 21 other vehicles, including the 1996 Chevrolet Chevy Van, 1995 GMC Yukon, 1995 GMC Vandura Special, 1995 GMC Vandura, and 1995 GMC Suburban. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
It takes PCM 20 seconds to learn TDC offset.
This procedure is only used when one of following conditions exists:
- Front cover and PCM are removed and replaced at same time.
- Injection pump and PCM are removed and replaced at same time.
- Front cover and/or crank sensor, pump and PCM are removed and replaced at same time.
- Front cover has been removed.
- Engine has been replaced.
- Start and warm engine to normal operating temperature. Connect Tech 1 scan tester. Using scan tester, select OUTPUT TEST or INJECTION PUMP mode, and activate TDC OFFSET LEARN.NOTE: If engine stalls when "TDC TIME SET" is activated, turn engine off, then slightly rotate injection pump toward driver's side of vehicle. Tighten mounting nuts and repeat step 1).
- If learned TDC OFFSET reading is between .00 and -.50 degrees, procedure is complete. If reading is not as specified, slightly rotate injection pump and repeat step 1). A 1-mm pump movement equals about 2 degrees timing.
- To achieve a negative reading, rotate pump toward driver's side. To achieve a positive reading, rotate pump toward passenger's side.