General Motors — Entering Sync Mode
Operation · Sync/Cruise system
From a General Motors owner's manual covering: Carb 5.7L, MP 5.0L, MP 5.7L, MP 6.0L. Check it applies to your exact model before use.
Procedure
- Position both throttles to their Idle/Start position and start both engines.
- Press the Syn/Cru Mode switch (A) to the ON position.
- Press the Speed Set/Cancel switch (B) to the Cancel position.
- With the Sync Lamp flashing or steady ON, slowly push the Slave engine throttle handle to the full forward position.
- The operator now has control of both engine speeds using the Master throttle handle only.
Source: General Motors owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.