4HI Lock Mode Power Flow

WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: 4HI Lock Mode Power Flow

Courtesy of GENERAL MOTORS CORP.

When shifting to the 4HI Lock mode, the encoder motor (4) turns the shift detent lever shaft (5), to rotate the shift detent lever cam (8). The cam action of the shift detent lever cam (8) moves the lockup mode shift fork rearward along with the lockup shift assembly sleeve (2). The lockup shift assembly sleeve (2) locks the mainshaft (1) to the drive sprocket (3). Torque is sent by the chain (6) to the front output shaft (7) and to the front axle. The torque distribution in this mode is now determined by vehicle dynamic conditions and weight distribution. The planetary differential is not operating, and both the front and rear propeller shafts are being driven at equal RPM, therefore giving a 4 high lock mode. This mode should only be used for extra traction during off road use. Using this mode on dry pavement causes tire scuffing.