DESCRIPTION
The NV271 transfer case is a part-time transfer case with a low-range gear system. It provides three operating ranges plus a NEUTRAL position. The low range position provides a gear reduction ratio of 2.72:1 for increased low speed torque capability.
The gear cases and extension are all of aluminum (Scheme 121) Drive sprockets and an interconnecting drive chain are used to transmit engine torque to the front/ rear propeller shafts. The mainshaft, input gear and front output shaft are supported by ball and needle bearings.
IDENTIFICATION
An identification tag (Scheme 122) is attached to the rear case of every transfer case. The tag provides the transfer case model number, assembly number, serial number, and low range ratio.
The transfer case serial number also represents the date of build.
Scheme 121
Scheme 122
The transfer case position sensor is an electronic device whose output can be interpreted to indicate the transfer case's current operating mode. The sensor consists of a five position, resistive multiplexed circuit which returns a specific resistance value to the Powertrain Control Module (PCM) for each transfer case operating mode. The sensor is located on the top of the transfer case, just left of the transfer case centerline and rides against the sector plate roostercomb. The PCM supplies 5VDC (+/- 0.5V) to the sensor and monitors the return voltage to determine the sector plate, and therefore the transfer case, position.
OPERATION
During normal vehicle operation, the Powertrain Control Module (PCM) monitors the transfer case position sensor return voltage to determine the operating mode of the transfer case. Refer to the OPERATING MODE VERSUS RESISTANCE table for the correct resistance for each position.
| SENSOR POSITION (1) | OPERATING MODE | SENSOR RESISTANCE (ohms) |
|---|---|---|
| 1 | 2H | 1172-1195 |
| 2 | 4H | 677-691 |
| 3 | NEUTRAL | 406-415 |
| 4 | 4L | 208-213 |
| 5 | NOT USED | 60-61 |
| (1) (Scheme 123) | ||
| (1) | (Scheme 123) |
OPERATING MODE VERSUS RESISTANCE
