Hall Sensor -- Explorer
Hall Sensor Power
GEM sends a regulated 12 volts to both front and rear Hall effect sensors.
Check at the 16-way transfer case motor harness connector Pins 3 and 7 for approximately 12 volts. If no voltage exists, check for continuity between GEM Connector C3-Pin 1 and transfer case harness. If continuity exists, check Hall sensor Connector Pin 3 or 7.
Hall Sensor Ground
Check transfer case harness Connector Pins 6 and 8 for ground. If no ground, check for continuity between GEM Connector C1-Pin 21 and Pins 6 and 8, if continuity exists.
Front Prop Shaft Hall Sensor Return
Check for continuity between GEM harness Connector J3-Pin 6 and transfer case 16-way harness Connector Pin 4. If continuity exists, replace front Hall sensor.
Rear Prop Shaft Hall Sensor Return
Check for continuity between GEM harness Connector J3-Pin 5 and transfer case 16-way Connector Pin 2. If continuity exists, replace rear Hall sensor.
Note:
To verify Hall sensors are functional, clear DTC and drive above 30 mph for 45 seconds in 4WD Auto.
If Hall sensors are functional and associated Connectors are firmly attached (GEM -- Harnesses -- T-Case Connector), Codes B1836 and/or B1837 should not reappear unless the new Hall sensors or the GEM is defective.
Sensors
Check the three sensors with the ignition on. The transmission sensors (manual or automatic) should be closed with the clutch in, or the automatic shift in neutral. The speed sensor should show 225-275 ohms with the vehicle stopped. Check at the module connection.
Shift Switch Checks
If the concern isn't in the sensors or the transfer case shift motor (7G360), check the control panel switches. Make this check with the ignition on. Disconnect the "B" and "C" connections to the sensors, so that their data won't confuse the diagnosis. Now check power at the C1 connection at the module. There should be 5 volts coming from the GEM to the 4H and 4L switch. Check C1, C2, and C3 for short to ground.
Check the switches themselves by disconnecting C1 and checking continuity across C1 to C2 and C1 to C3. If current passes when the switch buttons are pushed, the switches are OK.
Finally, check for a short between C2 and C3 by bridging between them and activating the 4H and 4L switch. 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.
No Range Shift Checks
If the vehicle won't shift into 4L, check the speed sensor brake switch input and the transmission interlocks (neutral or clutch in). Also check the 4L switch (C3) to see if the module is getting a signal. Check for corroded connections.
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.
Shifting on the Fly Isn't Smooth and May Require Stopping to Complete Shift
Look for concerns with the electromagnetic clutch. If the ratcheting or grinding goes on for more than four seconds, there may be a problem with power to the clutch from the GEM, the clutch ground or the clutch itself. Check the wiring harness as well.
Indicator Lamps Check
To check the lamps, turn the ignition on and ground C3 Pin 14 and C3 Pin 10 at the GEM on manual shift vehicles ground Circuit 783 (GY) and 784 (LB/BK) at the transfer case position switch. The lamps should light.
Indicator Lights Do Not Register the Correct Information
Ranger and Explorer have indicator lights in two locations. There are lights on the instrument panel and LED indicator lights in the switches. If the instrument panel lights don't respond, look for no power or a burned-out bulb.
If the lights are on all the time, look for a short to ground. Check to see if the generic electronic module is activating them all as this is a malfunction.
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.
If no lights illuminate as you go through the shifts and ground power and bulbs are good, then the GEM is at fault or the transfer case shift motor has stopped at an intermediate point.
I know where the t/c connector is so that is not a problem but am unsure about the c1 c2 and so on connectors. I guess it would help if I bought a haynes manual.
