Mechanics

4 WHEEL DRIVE ENGAGES ON ITS OWN WHILE DRIVING?

2001 Ford Ranger • 150,000 miles

While driving today all of a sudden it felt as if my truck went into low gear, it apparently went into 4 wheel drive. The indicator lights do not illuminate any more and when I switch back and forth between 4 high, 4 low, or 2 wheel drive it doesn't seem to do anything?
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Crashio
January 7, 2012.




TRANSFER CASE - FOUR WHEEL DRIVE SYSTEMS -2001 Ford Ranger
Page 1 of 10
ARTICLE BEGINNING

DESCRIPTION AND OPERATION

FOUR-WHEEL DRIVE SYSTEMS

Fig. 1: Identifying Transfer Case
The electronic shift on the fly system is an electronically-shifted four wheel drive system that allows the operator to choose between three different modes. The operator can switch between 2WD and
4WD HIGH modes at any speed. To engage or disengage 4WD LOW range, the vehicle speed must be less than 5 km/h (3 mph), the brake depressed, and the transmission must be in NEUTRAL
(automatic transmission) or the clutch pedal must be depressed (manual transmission).
The shift motor sense plate, an integral part of the electric shift motor, informs the four-wheel drive (4WD) control module of the transfer case position.
The digital transmission range (TR) sensor is located on the LH side of the automatic transmission; this sensor informs the 4WD control module when the automatic transmission is in the NEUTRAL
position.
The clutch pedal position (CPP) switch is present on manual transmission vehicles; this switch informs the 4WD control module when the clutch pedal is depressed.
The electric shift motor is mounted externally at the rear of the transfer case. It drives a rotary cam which moves the mode fork and range fork within the transfer case between the 4WD HIGH, 4WD
LOW and 2WD positions.
The 4WD shift motor is controlled by the 4WD control module to shift the transfer case between 4WD HIGH, 4WD LOW and 2WD modes.
System Function

Feature inputs: ? Brake On/Off Switch
? Mode Select Switch (MSS)
? Digital Transmission Range (TR) Sensor
? Vehicle Speed Signal Transmitted From The Powertrain Control Module (PCM) ? Contact Plate Position Inputs A, B, C, D
Feature outputs: ? 4WD LOW Indicator (Ground When Activated, Open Circuit When Deactivated) ? 4WD HIGH Indicator (Ground When Activated, Open Circuit When Deactivated)

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? 4WD Shift Motor Outputs
Shifts between 2WD and 4WD HIGH can be made at any speed. Listed below are the inputs and outputs needed by the 4WD control module to execute a change between any of these modes.
Feature inputs: ? Vehicle Speed Signal \? Mode Select Switch
Feature outputs: ? 4WD HIGH Cluster Indicator (Ground When Activated, Open Circuit When Deactivated)
When shifting into or out of LOW range, the 4WD control module requires that the vehicle speed is less than 5 km/h (3 mph), the brake is applied, and the transmission is in NEUTRAL.
Feature inputs: ? Mode Select Switch
? Contact Plate Position Inputs A, B, C, D ? Vehicle Speed Signal
? Brake On/Off Switch Input (Battery Voltage When Brake Is Depressed, Open Circuit When Not Activated)
? Digital Transmission Range Sensor (Ground When Transmission Is In NEUTRAL, Open Circuit Otherwise)
Feature outputs: ? 4WD Shift Motor Outputs
? 4WD LOW Cluster Indicator (Ground When Activated, Open Circuit When Deactivated)
DIAGNOSIS AND TESTING

FOUR-WHEEL DRIVE SYSTEMS-ELECTRONIC SHIFT

Fig. 2: Identifying Special Tool(s)
Principles of Operation

Transfer Case - Electronic Shift

The four-wheel drive electronic shift-on-the-fly feature electrically shifts the vehicle transfer case between 2WD, 4WD HIGH, and 4WD LOW. The system mode is selected by the operator through
the mode select switch (MSS) on the instrument panel. The operator is informed which mode the system is in by two instrument cluster indicators: one for 4WD HIGH which appears as 4WD HIGH,

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TRANSFER CASE - FOUR WHEEL DRIVE SYSTEMS -2001 Ford Ranger
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and one for 4WD LOW, which appears as 4WD LOW. Shifts into 4WD HIGH can be made at any speed. When shifting into 4WD HIGH with the vehicle stationary, tooth blockage may occur
preventing shift completion. When the vehicle is driven above 8 km/h (5 mph) the shift will complete. When shifting in or out of 4WD LOW, the four-wheel drive (4WD) control module
requires that the vehicle speed be less than 5 km/h (3 mph), the brake pedal be applied, and the transmission be in NEUTRAL (automatic transmission) or the clutch pedal be depressed (manual
transmission).
The gearmotor encoder assembly is mounted externally on the transfer case. It drives a rotary cam which moves the mode fork and range fork within the transfer case between the 4WD HIGH, 4WD
LOW, and 2WD range positions.
The four-wheel drive (4WD) control module controls the gearmotor encoder assembly that shifts between 4WD HIGH, 4WD LOW, and 2WD modes.
The 4WD control module accomplishes shifts by interpreting inputs from the following: ? Mode Select Switch (MSS) \? Vehicle Speed Signal
? Encoder Plate Position ? Brake Pedal Switch
? Digital Transmission Range (TR) Sensor ? Ignition Switch
? Gearmotor Encoder Assembly
Based on these inputs, the 4WD control module controls the shifts into 2WD, 4WD HIGH or 4WD LOW with the following outputs: ? Gearmotor (Clockwise)
? Gearmotor (Counterclockwise)
Inspection and Verification - Electronic Shift

1.
Visually inspect the following for obvious signs of mechanical and electrical damage.
Fig. 3: Visual Inspection Chart
2.
If the concern remains after the inspection, connect the diagnostic tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from
the diagnostic tool menu. If the diagnostic tool does not communicate with the vehicle: ? Check that the program card is correctly installed.
? Check the connections to the vehicle. ? Check the ignition switch position.
If the diagnostic tool still does not communicate with the vehicle, refer to the diagnostic tool manual.
4. Carry out the DATA LINK DIAGNOSTICS test. If the diagnostic tool responds with: 3.

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? CKT914, CKT915 or CKT70 = ALL ECUS NO RESP/NOT EQUIP, refer to MODULE COMMUNICATIONS NETWORK article.
? NO RESP/NOT EQUIP for 4WD control module, go to PINPOINT TEST B.
? SYSTEM PASSED, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and carry out the 4WD control module self-test.
If the DTCs retrieved are related to the concern, go to the 4WD Control Module Diagnostic Trouble Code (DTC) Index to continue diagnostics. See Fig. 4 - Fig. 5.
6. If no DTCs related to the concern are retrieved, carry out the Electronic Shift Function Test. Refer to PINPOINT TEST A.
5.
4WD Control Module Diagnostic Trouble Codes (DTCS)

4WD CONTROL MODULE DIAGNOSTIC TROUBLE CODES (DTCS)
DTC B1342
Description ECU Defective
Source 4WD Control
Module
Perform Test Clear DTC. Repeat 4WD control
module self-test. If DTC B1342 is retreved, install a new 4WD control
module. Clear DTCs and repeat self-test C
B1355
Ignition Run Circuit Failure
Brake Pedal Input Circuit Failure
Brake Pedal Input Battery Short
Ignition Run/Start Circuit Failure
Transfer Case Unable To Transition
Between 2WD HIGH and 4WD HIGH
Transfer Case Unable To Transition
Between 4WD HIGH And 4WD LOW
Vehicle Speed Sensor (VSS) Malfunction
Transmission 4WD Mode Select Circuit
Failure Transmission 4WD
Mode Select Short Circuit To Ground
Transmission Neutral Safety Switch Circuit
Failure Transmission Neutral
Safety Switch Circuit
4WD Control Module
4WD Control Module
4WD Control Module
4WD Control Module
4WD Control Module
D
B1483
B1485
D
C
B1555
C1728
Perform electronic shift function test in A
C1729
4WD Control Module
Perform electronic shift function test in A
D
P0500
4WD Control Module
4WD Control Module
C
P1812
C
P1815
4WD Control Module
D
P1816
4WD Control Module
D
P1819
4WD Control Module

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To Ground Transmission Transfer
Case Contact Plate A Short Circuit To
Ground Transmission Transfer
Case Contact Plate B Short Circuit To
Ground Transmission Transfer
Case Contact Plate C Short Circuit To
Ground Transmission Transfer
Case Contact Plate D Short Circuit To
Ground Transmission Transfer
Case Contact Plate General Circuit
Failure Transmission Tansfer
Case Contact Plate Ground Return Open
Circuit
C
P1849
4WD Control Module
C
P1853
4WD Control Module
C
P1857
4WD Control Module
C
P1861
4WD Control Module
C
P1867
4WD Control Module
C
P1891
4WD Control Module
Fig. 4: 4WD Control Module Diagnostic Trouble Codes (DTC) (1 Of 2)
Fig. 5: 4WD Control Module Diagnostic Trouble Codes (DTC) (2 Of 2)
Functional Test - Electronic Shift

Pinpoint Test A: Electronic Shift Functional Test

CAUTION: The function test must be carried out on a hard surface in a vacant area without traffic.
Fig. 6: Pinpoint Test A: Electronic Shift Functional Test (Steps A1-A3)
Fig. 7: Pinpoint Test A: Electronic Shift Functional Test (Steps A3 Cont.-A4)
Fig. 8: Pinpoint Test A: Electronic Shift Functional Test (Steps A5-A7)
Fig. 9: Pinpoint Test A: Electronic Shift Functional Test (Steps A7 Cont.-A9)
Fig. 10: Pinpoint Test A: Electronic Shift Functional Test (Steps A9 Cont.-A11)

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Fig. 11: Pinpoint Test A: Electronic Shift Functional Test (Steps A11 Cont.-A13)
Fig. 12: Pinpoint Test A: Electronic Shift Functional Test (Steps A13 Cont.-A15)
Fig. 13: Pinpoint Test A: Electronic Shift Functional Test (Steps A15 Cont.- A17)
Fig. 14: Pinpoint Test A: Electronic Shift Functional Test (Steps A17 Cont.- A19)
Fig. 15: Pinpoint Test A: Electronic Shift Functional Test (Steps A19 Cont.-A20)
Symptom Chart - Electronic Shift

Fig. 16: Symptom Chart (1 Of 2)
Fig. 17: Symptom Chart (2 Of 2)
Pinpoint Tests - Electronic Shift

Pinpoint Test B: No Communication With The Four-Wheel Drive (4WD) Control Module

Fig. 18: Pinpoint Test B: No Communication With The Four-Wheel Drive (4WD) Control Module (Step B1)
Fig. 19: Pinpoint Test B: No Communication With The Four-Wheel Drive (4WD) Control Module (Step B2)
Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly

Fig. 20: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Step C1)
Fig. 21: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C2-C4)
Fig. 22: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C4 Cont.-C5)
Fig. 23: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C6-C7)
Fig. 24: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C8-C10)
Fig. 25: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C10 Cont.-C11)
Fig. 26: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C11 Cont.-C12)

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Fig. 27: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C13-C14)
Fig. 28: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C14 Cont.-C16)
Fig. 29: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C16 Cont.-C17)
Fig. 30: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C18-C19)
Fig. 31: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Step C20)
Fig. 32: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Steps C21-C22)
Fig. 33: Pinpoint Test C: The Vehicle Does Not Shift Between 2WD & 4WD Modes Correctly (Step C23)
Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly

Fig. 34: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Step D1)
Fig. 35: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D2-D4)
Fig. 36: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D4 Cont.-D6)
Fig. 37: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D6 Cont.-D7)
Fig. 38: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D8-D9)
Fig. 39: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D10-D11)
Fig. 40: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D12-D13)
Fig. 41: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D14-D15)
Fig. 42: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D16-D17)

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Fig. 43: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D17 Cont.-D18)
Fig. 44: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D18 Cont.-D19)
Fig. 45: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D20-D21)
Fig. 46: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D22-D23)
Fig. 47: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D23 Cont.-D25)
Fig. 48: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Steps D26-D27)
Fig. 49: Pinpoint Test D: The Vehicle Does Not Shift Between 4WD High & 4WD Low Modes Correctly (Step D28)
REMOVAL AND INSTALLATION

MODE SELECT SWITCH (MSS)

Removal and Installation

1. 2.
Removal the mode select switch (MSS) ****. \ Remove the audio unit.
Fig. 50: Identifying Mode Select Switch
3.
Remove the screws and pull the instrument panel center finish panel out of the instrument panel.
Fig. 51: Pulling Instrument Panel Center Finish Panel Out Of Instrument Panel
4.
Disconnect the harness connector, remove the two screws and the MSS.
Fig. 52: Removing 2 Screws & MSS
5.
To install, reverse the removal procedure.
GEARMOTOR ENCODER ASSEMBLY

Removal and Installation

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1.
Set the mode select switch to the 4X4 HIGH position.
Fig. 53: Setting Mode Select Switch To 4X4 HIGH
2. 3.
Raise and support the vehicle.
Disconnect the gearmotor encoder assembly harness connector.
Fig. 54: Disconnecting Gearmotor Encoder Assembly Harness Connector
4.
Remove the bracket bolt and the gearmotor encoder assembly mounting bolts and remove the gearmotor encoder assembly.
Fig. 55: Removing Bracket Bolt & Gearmotor Encoder Assembly Mounting Bolts
5.
Remove the grease from the motor adapter and check for any nicks or burrs. If any damage is found, repair or install a new gearmotor encoder assembly as necessary.
To install, reverse the removal procedure.
6.
? Apply a coat of multi-purpose grease to the gearmotor encoder assembly.
FOUR-WHEEL DRIVE (4WD) CONTROL MODULE

Removal and Installation

1. 2.
Remove the passenger cowl side trim panel. Remove the 4WD control module.
1. 2. 3.
Disengage the locking tangs and remove the harness connectors. Remove the screws.
Remove the 4WD control module.
Fig. 56: Removing 4WD Control Module
4.
To install, reverse the removal procedure.
SPECIFICATIONS

General Specifications
Item Multi-Purpose Grease DOAZ-19584-AA
Specification ESB-M1C93-B
Torque Specifications
Description Gearmotor encoder assembly mounting bolts
Nm 20
Lb-Ft 15
Lb-In ---

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1/7/2012

Rivermikerat
Jan 8, 2012.


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