NEW PROCESS MODEL 241
An identification tag is attached to the rear case half. The tag provides the transfer case model number, low range reduction ratio and assembly part number.
BORG-WARNER MODELS 1370 & 4470
An identification tag is attached to an extension housing bolt. The tag provides the transfer case model number, serial number, build date and low range reduction ratio.
DESCRIPTION
The transfer case is used to provide power flow to the front axle. The transfer case also provides a means of disconnecting the front axle, providing for better fuel economy and, quieter operation when the vehicle is driven on improved roads where four wheel drive is not required. In addition, the transfer case provides for an additional gear reduction when placed in low range, which is useful when difficult off-road conditions are encountered.
A New Process Model 241 transfer case is used on all vehicles except K30 Models with dual rear wheels (RPO-R05). The K30 Model with dual rear wheels uses the Borg-Warner Models 1370 or 4470 transfer case.
All three models are aluminum case, chain driven units with four modes of operation: neutral, two wheel drive high range, four wheel drive high range, and four wheel drive low range. Gear reduction for low range is provided by a planetary gear set.
A floor mounted shift lever is used to select the operation range. Indicator lights on the floor console show the current mode of operation. When four wheel drive has been selected, the four wheel drive indicator light is designed to come on when the front axle has engaged. A slight delay for the front axle indicator light to come on is normal.
NORMAL OPERATION (2WD)
When the transfer case is in "2 WHEEL" range, torque flows from the input gear to the range shift hub and main shaft, through the drive shaft, to the rear axle. A switch in the shifter mechanism causes the "2 WHEEL" indicator light to turn on.
HIGH RANGE OPERATION (4WD)
Shifting into "4 HIGH" range causes the following to happen
- A switch in the shifter mechanism causes "2 WHEEL" indicator light to turn off and the "4 HIGH" indicator light to turn on. The front axle indicator light does not come on immediately.
- Torque flows from the input gear to the mainshaft the same as in "2 wheel" position. The shift linkage moves the mode synchronizer sleeve into engagement with the clutch teeth of the drive sprocket. This locks the drive sprocket to the mainshaft through the synchronizer sleeve.
- Torque is transmitted through the drive sprocket and drive chain to the driven sprocket and output shaft. Torque then flows through the front drive shaft to the front axle.
- The shift mechanism is the transfer case closes a switch. Current is then applied to the front axle thermal actuator.
- The terminal actuator contains a heating element, a gas charge, and a piston. When current is applied, the heating element heats the gas. The gas expands, pushing the piston out after a delay of a few seconds. The piston actuates the shift fork in the front axle. This connects the right axle output shaft to the front axle differential. Torque is then available at the front wheels.
- The front axle shift mechanism, when fully engaged, closes a switch, causing the front axle indicator light to come on.
- If the shift lever is moved back to "2 WHEEL" position, the operation in the preceding steps is reversed. The current to the thermal actuator is turned off. The gas cools, and the piston retracts, allowing the shift fork in the front axle to return to the two-wheel drive position.
LOW RANGE OPERATION (4WD)
- When the transfer case is shifted into "4 LOW" position torque flow and operation is similar to "4 HIGH" range, except that the range shift hub engages the planetary carrier. The planetary gear set then provides a gear reduction to both the front and rear axles.
- A switch in the shift mechanism causes the "4 HI" indicator light to turn off and the "4 LO" indicator light to turn on.
ELECTRONIC SYNCHRONIZER OPERATION (MODEL 1370 & 4470 ONLY)
The electronic synchronizer is used in model 1370 and 4470 transfer cases to provide smoother shifting. The system requires no maintenance or service.
The system consists of a relay and a clutch coil (electromagnet) inside the transfer case. The clutch coil replaces the conventional blocker ring. When energized, the clutch coil provides synchronization, resulting in a smooth shift. When the transfer case lever is moved to "4 HI" or "4 LO" position, current is supplied to the normally closed relay. (Scheme 1) Current flows through the relay to the clutch coil. When the front axle engages, the axle switch energizes the relay coil. The relay switch then opens, and current to the clutch coil is interrupted.
FOUR WHEEL DRIVE DOES NOT ENGAGE
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Blown A/C-HTR Fuse. | Replace. |
| Faulty transfer sw. | Replace. |
| Faulty 4WD Indicator light, sw, or wiring (4WD engaging but indicator light not coming on. | Repair as needed. |
| Transfer case linkage improperly adjusted or disconnected. | Adjust or repair. |
| Faulty transfer case: Drive chain broken, range selector ring broken | Repair |
| Faulty front axle. | Repair |
TRANSFER CASE DIAGNOSIS
FOUR WHEEL DRIVE ENGAGES BUT INDICATOR LAMP WILL NOT LIGHT
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Blown bulb. | Replace. |
| A/C-HTR fuse blown. | Replace. |
| Faulty front axle sw. | Replace. |
| Faulty wiring. | Repair open in wiring. |
FOUR WHEEL DRIVE ENGAGES BUT INDICATOR LAMP WILL NOT LIGHT
4WD INDICATOR LIGHT WON'T TURN OFF (4WD DISENGAGES PROPERLY)
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Faulty front axle sw. | Replace. |
4WD INDICATOR LIGHT WON'T TURN OFF (4WD DISENGAGES PROPERLY)
FOUR WHEEL DRIVE WILL NOT DISENGAGE
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Faulty wiring or front axle sw. (4WD disengaging but indicator light staying on). | Replace or repair wiring. |
| Transfer case linkage binding or improperly adjusted. | Replace or repair. |
| Faulty front axle shift mechanism. | Repair |
FOUR WHEEL DRIVE WILL NOT DISENGAGE
JUMPS OUT OF FOUR WHEEL DRIVE
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Transfer case linkage binding or improperly adjusted. | Replace. |
| Worn or damaged engine or trans. mountings. | Replace |
| Transfer case mounting bolts loose | Tighten. |
| Drive shaft slip splines dry or loose. | Lubricate or replace |
| Transfer case or front axle internal problem. | Repair |
JUMPS OUT OF FOUR WHEEL DRIVE
TRANSFER CASE SHIFT LEVER HARD TO SHIFT OR WON'T SHIFT INTO 4 LOW OR NEUTRAL (VEHICLE MOVING)
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Vehicle in motion when attempting to shift. Stop vehicle when shifting into or out of 4 "LO" or "NEUTRAL". or wiring (4WD engaging but indicator light not coming on. | None is required. |
SHIFT LEVER HARD TO SHIFT OR WON'T SHIFT INTO 4 LOW OR NEUTRAL (VEHICLE MOVING)
TRANSFER CASE DIFFICULT TO SHIFT
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| In extremely cold weather, it may be necessary to reduce vehicle speed or stop before shifting from 2 Wheel to 4 High. indicator light not coming on. | None is required. |
| If vehicle has been operated for an extended period in 4 High mode on dry pavement, difficult shifting may result due to driveline torque lock. Stop vehicle, shift transmission to neutral and shift transfer case into desired mode. | Operate vehicle in 2 WHEEL mode on dry pave- ment. Oversize under-inflated tires may also cause torque. |
| Transfer case linkage binding. | Adjust or repair. |
| Low transfer case lubricant level or improper lubricant used. | Fill with proper lubricant. |
| Internal transfer case problem. | Repair. |
| Faulty wiring or electronic synchronizer (Models 1370 & 4470) | Test as outlined later & repair as needed. |
TRANSFER CASE DIFFICULT TO SHIFT
TRANSFER CASE NOISY IN ALL MODES
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Low lube level, or improper lubricant used. | Fill with proper lubricant. |
| Worn, under-inflated or over-sized tires. | Replace or inflate. |
| Internal transfer case problem. | Repair. |
TRANSFER CASE NOISY IN ALL MODES
NOISY IN OR JUMPS OUT OF 4 LOW RANGE
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Transfer case not completely engaged in 4 LOW range. Stop vehicle, shift into NEUTRAL, then back to 4 LOW. | None required. |
| Shift linkage loose or binding. | Repair. |
| Transfer case internal shift mechanism faulty. | Repair or replace. |
NOISY IN OR JUMPS OUT OF 4 LOW RANGE
LUBRICANT LEAKING FROM TRANSFER CASE VENT
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Transfer case overfilled. | Drain lubricant to proper level. |
LUBRICANT LEAKING FROM TRANSFER CASE VENT
LUBRICANT LEAK AT OUTPUT SHAFT SEALS
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Transfer case overfilled. | Drain lubricant to proper level. |
| Vent hose plugged or kinked. | Repair. |
| Output shaft seals damaged or incorrectly installed. | Replace. |
LUBRICANT LEAK AT OUTPUT SHAFT SEALS
ABNORMAL FRONT TIRE WEAR
| POSSIBLE CAUSE | CORRECTION |
|---|---|
| Front end needs alignment. | Align to specifica- tions. |
| Extended operation on hard, dry surfaces in 4 HIGH mode. | Operate vehicle in 2 WHEEL mode on hard, dry surfaces. |
ABNORMAL FRONT TIRE WEAR
ELECTRONIC SYNCHRONIZER SYSTEM CHECK (1370 & 4470 ONLY)
- Place ignition switch in RUN position, with 4WD engaged. It may be necessary to rotate the front tires slightly for the front axle to fully engage.
- Electronic synchronizer connector at the transfer case. Connect a test lamp from the wiring harness read wire connector ground. The test lamp should light.
- If the test lamp does not light, check the ckt. for opens. If none are found, replace the relay as outlined later.
- If the test lamp lights in step 2, check the synchronizer coil for continuity. If the coil is open, replace it. If the synchronizer coil has continuity, it is probably OK. Recheck fluid levels, linkage adjustments, etc. before presuming the synchronizer to be faulty.
REMOVAL
Raise vehicle. Support with suitable safety stands. Place a drain pan under drain plug.
Drain plug. Allow oil to drain. Fill plug.
INSTALLATION
Drain plug. Tighten drain plug to 18 ft.lbs. (25 N.m). Install oil and filler plug. Tighten filler plug to 18 ft.lbs. (25 N.m). Lower vehicle.
