93 Explorer Elec. Transfer Case Shift Diagnostics

1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 1 Transfer Case: Testing and Inspection Electronic Shift Diagnosis Check Lamps Electronic Shift Transfer Case Schematic To check the lamps, turn the ignition ON and ground C4 and C5. The lamps should light. Check Shift Switches 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 2 Electronic Shift Transfer Case Schematic It the problem isn't in the Sensors or the Motor, check the CONTROL PANEL SWITCHES. 1. Make this check with the ignition ON. 2. DISCONNECT the "B" and "C" connections to the Sensors, so that their data won't confuse the diagnosis. 3. Now check POWER at the C1 connection at the Module. 4. There should be 5 volts coming from the Shift Control Module to the 4H and 4L switches. 5. Check C1, C2, and C3 for short to ground. 6. Check the Switches themselves by DISCONNECTING C1 and checking CONTINUITY across C1 to C2, and C1 to C3. 7. If current passes when the switch buttons are PUSHED, the switches are OK. 8. Finally, check for a short between C2 and C3 by bridging between them and activating the 4H and 4L buttons. There are situations where wiring harnesses get crushed in such a way that TWO wires are crushed together and short, even though there is no short to ground. Check Transfer Case Shift Motor "Ford provides additional testing for the transfer case shift motor, refer to: Control Module Circuits : Control Module Circuits (Includes Shift Motor Circuit Testing) for additional test information (Ohmmeter Readings Fro Shift Motor)" See: Component Tests/Control Module Circuits (Includes Shift Motor Circut Testing) 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 3 Electronic Shift Transfer Case Schematic 1. To check if the Transfer Case Shift Motor is actually functioning (because it may be hard to hear it in a noisy shop) attach a voltmeter to A4 and A5. 2. Have someone activate a shift and look for a brief (one second) increase in voltage, and listen for the relay to click ON, then OFF. 3. If there is power present, then the Control Module is trying to run the Motor. At this point, unbolt the motor and have someone activate a shift again. 4. If the motor doesn't actually turn, it is malfunctioning and must be replaced. 5. If there is no power to the Motor, check both the POWER CIRCUITS again and the SENSORS. 6. If there is incorrect sensor data, the Module won't power the Motor. Control Module Circuits (Includes Shift Motor Circut Testing) 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 4 Control Module and Wiring Harness, Explorer 4-Door 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 5 Control Module and Wiring Harness, Explorer 2-Door There are three wiring harnesses connected to the Electronic Control Module (ECM): ^ The Eight-Wire Pigtail Harness Connector. ^ The Five-Wire Harness Connector. ^ The Eight-Wire Harness Connector. To check the integrity of these circuits, disconnect the harnesses from the ECM and perform the following checks: EIGHT-WIRE PIGTAIL HARNESS CONNECTOR 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 6 Eight-Wire Pigtail Harness Connector 1. Connect a voltmeter between terminal 8 and ground. The voltmeter should indicate battery voltage at all times. 2. Connect a voltmeter between terminal 7 and ground, then turn ignition switch to RUN position. The voltmeter should indicate battery voltage. CAUTION: In the following sections where the usage of an ohmmeter is specified, always remember that an ohmmeter should NEVER be connected into a "live" or powered circuit. If the ohmmeter is subjected to a powered circuit, severe damage will be done to the instrument. The vehicle's battery should be disconnected before performing checks on any circuit with an ohmmeter to prevent any accidental damage to the instrument. 3. 4. 5. 6. Connect an ohmmeter between terminal 6 and ground. The ohmmeter should indicate less than 10 ohms resistance. Connect an ohmmeter between terminals 4 and 5. The ohmmeter should indicate less than 10 ohms resistance. Connect an ohmmeter between terminal 3 and ground. The ohmmeter should indicate 0 ohms. Connect an ohmmeter between terminal 2 and ground. The ohmmeter should indicate 0 ohms. FIVE-WIRE PIGTAIL HARNESS CONNECTOR Fig. 7 Five-wire Pigtail Harness Connector (Electronic Shift) C300 1. Connect an ohmmeter between terminals 1 and 2, then DEPRESS the 4x4 (2H-4H) switch. The ohmmeter should indicate a very "low" resistance value (less than 50 ohms) while the switch is being DEPRESSED. 2. Connect ohmmeter between terminals 1 and 3, then DEPRESS the Low Range switch. The ohmmeter should indicate a very "low" resistance value (less than 50 ohms) while the switch is being DEPRESSED. 3. Connect a test lead between terminals 4 and ground, then turn ignition switch to RUN position and observe the indicator lights. The LOW RANGE light in the instrument panel and LOW RANGE indicator light on the switch should illuminate. 4. Connect a test lead between terminal 5 and ground, then turn ignition switch to RUN and observe the indicator lights. The 4x4 light in the instrument panel and 4x4 light on the switch should illuminate. 1993 Ford Truck Explorer 4WD V6-245 4.0L EIGHT-WIRE HARNESS CONNECTOR Copyright © 2008, ALLDATA 9.90 Page 7 Eight-Wire Harness Connector 1. Connect an ohmmeter between terminal 1 and ground. On a vehicle equipped with a Manual Transmission (M/T), DEPRESS the clutch pedal and observe the ohmmeter. The ohmmeter should indicate a "low" resistance (less than 50 ohms) while the clutch pedal is being depressed. If vehicle is equipped with an Automatic Transmission (A/T), shift the transmission into the "NEUTRAL" position and observe the ohmmeter. The ohmmeter should indicate a "low" resistance (less than 50 ohms) while the transmission selector lever is in the "NEUTRAL" position. 2. Connect an ohmmeter between terminals 2 and 3. The ohmmeter should indicate a "low" resistance (225-275 ohms). This will check the continuity of the speed sensor that is located in the transfer case. The speed sensor picks up the rotating speed of the output shaft from two notches that are cut in opposite sides of the outer ring of the clutch housing assembly. 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 8 Ohmmeter Readings For Shift Motor Position Sensor 3. Connect an ohmmeter between terminal 8 and terminals 4, 5, 6 and 7, respectively. Refer to the illustration for the appropriate ohmmeter readings in each transfer case position. Electric Shift Operations Shift Operations If the system operates improperly, or will not operate at all, a problem could exist in the push-button control switches, Electronic Control Module (ECM), Speed Sensor, Electric Shift Motor, Electro-Magnetic Clutch Assembly, Clutch Interlock Switch, Neutral Safety Switch, or the interconnecting wiring. Use the guidelines and test procedures to assist in locating the cause of a problem. Circuit Protection The battery feed circuit, through a circuit breaker, provides memory capability for the ECM. Ignition RUN or START feed circuits, through a fuse, provide power for switches and the electronic shift motor. Indicator Lights Don't Register the Correct Information 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 9 Electronic Shift Transfer Case Schematic 1. The indicator lights are in two locations. There are lights on the dash and LED indicator lights in the switches. If the dash lights don't respond, look for no power or a burned-out bulb. 2. If the lights are ON all the time, look for a short to ground. Check to see if the Shift Control Module is activating them all as this is a malfunction. 3. If the button lights remain ON all the time but the dash lights are not ON, this means the dash lights have burned out. The button lights are ON because a LOW current is still passing across, enough to light the LED. 4. If NO lights illuminate as you go through the shifts and ground power, and the bulbs are good, then the Module is at fault or the Motor has stopped at an intermediate point. Power In 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 10 Electronic Shift Transfer Case Schematic Power is supplied to the system at three points (P1, P2, and P3 in the schematic). P1. This is a direct connection to the battery. This power drives the electric shift control motor and provides current to the instrument cluster lamps. This circuit goes to ground G1. P2. The electronic shift control module is tied into the ignition circuit. This circuit provides power to the computer and goes to ground G2. P3. Nighttime illumination is provided by a connection to the vehicle's nighttime illumination circuit, which goes to ground G3. The Electronic Shift Control Module directs power depending on the position of the control switches. In the schematic, you will notice that INPUTS and OUTPUTS to and from the Shift Module are labeled A, B or C. A circuits are POWER CIRCUITS, B circuits are DATA CIRCUITS from SENSORS, and C circuits are ACTIVATING SWITCH and RELATED LAMP CIRCUITS. The B circuits supply data from THREE sources: The Speed Sensor, the Motor Position Sensor, and either a Park/Neutral Position Switch (for automatic transmissions) or a Clutch Pedal Position switch (for manual transmissions). The Speed Sensor is important because the vehicle must be stopped for a shift into or out of 4L. The shift module won't make the shift if the vehicle is moving. The shift module also won't make a shift to 4L or back unless the automatic transmission is in NEUTRAL, or the clutch is DEPRESSED on a manual transmission. 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 11 Shift Motor Rotation The Motor Position Sensor indicates the position of the Shift Motor Shaft. This shaft turns through approximately 270° and should STOP at THREE indexed points, 2H, 4H, and 4L. The Shift Control Module needs to know where the shaft is before making a new shift. When this sensor isn't functioning properly or the motor stops slightly off location, the Shift Control Module may become "confused." The C circuits involve the switches on the vehicle's Control Panel. When everything is working properly, activating a switch will result in either a shift from 2H to 4H or back, or a shift from 4H to 4L or back. The default operating mode is 2H. This means that in the absence of other instructions, the Shift Control Module will assume that the vehicle should be in 2H. If there is a failure in the system during shifts or engine start up, it will default the vehicle to 2H and permit continued operation. Sensors Electronic Shift Transfer Case Schematic 1. Check the THREE sensors with the ignition ON. a. The Transmission Sensors (manual or automatic) should be CLOSED with the clutch IN, or the automatic shift in NEUTRAL. 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 12 b. The Speed Sensor should show 225-275 ohms with the vehicle STOPPED. Check at the Module connection. Shift Motor Positions 2. Check both the Motor Position Sensors and the wiring harness at B4, B5, B6, and B7 and the INPUT from B8. Make sure the harness is OK, then check the contacts against the chart. a. Each valid combination of OPEN and CLOSED switches indicates a different position of the Motor. For example: ^ At the 4H position, B7 is CLOSED, B6 is CLOSED, B5 is OPEN and B4 is OPEN. b. Besides the THREE main positions (2H, 4H and 4L), INTERMEDIATE positions are also shown: ^ THREE between 2H and 4H and THREE between 4H and 4L. c. Combinations other than those shown in the chart indicate a defective Motor Sensor Assembly. Transfer Case Feed Harness Circuits Transfer Case Feed Harness Location For Borg-Warner Model 13-54 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 13 Electronic Transfer Case Feed Harness The electric transfer case feed harness contains ten wires that carry a variety of information to and from the Electronic Control Module (ECM). A listing of the transfer case feed harness circuits and their functions follows: 1. The Electro-Magnetic Clutch Feed circuit provides a power signal to the clutch coil from the ECM when shifting from 2W to 4W. 2. CLOCKWISE rotation of the electric shift motor circuit provides power to drive the shift motor through the 2H-4H-4L sequence. 3. COUNTERCLOCKWISE rotation of the electric shift motor circuit provides power to drive the shift through the 4L-4H-2H sequence. 4. Actuation of the 4x4 switch while in 2H will cause a shift into 4H. Actuation of the 4x4 switch while in 4H will cause a shift into 2H. NOTE: The module will not respond to actuation of the 4x4 switch while in 4L. 5. Actuation of the LOW RANGE switch while in 4H will cause a shift into 4L providing the following conditions are met: 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 14 a. Automatic transmission is in NEUTRAL position or the clutch pedal is depressed (manual transmission). b. Vehicle speed is below 3 mph. 6. Actuation of the LOW RANGE switch while in 4L will cause a shift into 4H providing the above conditions exist. NOTE: The module will not respond to actuation of the 4x4 switch while in 4L. 7. Shift position sensor return circuits provide the output information signals from the transfer case to the ECM. This information gives the ECM the correct position of the shift that turns the helical cam in the transfer case. At Start Up, the Vehicle Shifts on Its Own Electronic Shift Transfer Case Schematic This can occur when the Motor Position Sensor indicates an INTERMEDIATE POSITION between 4H and 4L. If the vehicle is started in PARK instead of NEUTRAL, when the Driver first moves the transmission shift lever to DRIVE, the transmission passes through NEUTRAL. As it passes through NEUTRAL, the Shift Module activates the shift called for by the misinformation from the Motor Position Sensor. On Manual Transmissions or Automatic Transmissions started in NEUTRAL, the shift occurs immediately. This may be a one-time only event. However, the Motor Position Sensor should be checked if it happens frequently. No Range Shift 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 15 Electronic Shift Transfer Case Schematic 1. If the vehicle won't shift into 4L, check the SPEED SENSOR and the TRANSMISSION INTERLOCKS (NEUTRAL or clutch IN). 2. Also check the 4L switch (C3) to see if the Module is getting a signal. Check for corroded connections. 3. If the vehicle won't shift back to 4H, follow the proper sequence of being stopped and having the vehicle in NEUTRAL (or Clutch IN) when PUSHING the switch. Check the 4L switch and the Motor Position Sensor. Nothing Happens (Dead System) 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 16 Electronic Shift Transfer Case Schematic The obvious first step in diagnosing a dead system is to check the POWER SOURCES, FUSES AND GROUNDS. If these check out, perform the Shift Control Module Diagnostic Test. The illustration shows the Module with pigtail A, B and C attachments. The Diagnostic Test button and Diagnostic Test LED are located on the side of the Shift Control Module. 1. DISCONNECT the B and C connectors, turn ON the ignition and allow 4 seconds for the Module to power up. 2. Then PUSH the Diagnostic Test button. a. If the LED doesn't illuminate, the Module is dead and must be replaced. b. If the LED comes on and stays on for 30 seconds, there is an error condition and the module will have to be replaced. c. If the module is OK the LED will flash 4 times. This test, however, is not 100 percent accurate. During the test, the vehicle isn't operating, so the Shift Control Module isn't receiving data and initiating shifts. If the unit passes the Diagnostic Test, it's probably a good Module. Check for other probable causes, although the Module may need to be replaced even after passing the Diagnostic Test. Shift from 2H/4L to 4H, Module Chatter/Clicking Noises-No Shift 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 17 Electronic Shift Transfer Case Schematic Shift From 2H to 4H Results in Chatter and Clicking Noises from the Module, But NO Shift Typically, in this situation the Motor hunts for 4H, but overshoots, then hunts back and overshoots the other way. After 7-10 seconds, the Module returns to the default, which is 2H. This problem is normally not the sensor input. It is usually the result of the Motor running too fast or braking too slowly to allow the Module to position it accurately. The motor must be replaced. Shifting on the Fly Not Smooth, Requires Stopping to Shift 1993 Ford Truck Explorer 4WD V6-245 4.0L Copyright © 2008, ALLDATA 9.90 Page 18 Electronic Shift Transfer Case Schematic Shifting on the Fly Isn't Smooth and May Require Stopping in Order to Complete the Shift Look for problems with the Electric Magnetic Clutch. If the ratcheting or grinding goes on for more than 4 seconds, there may be a problem with power to the clutch from the Shift Control Module, the clutch ground, or the clutch itself. Check the wiring harness as well.