No ,not tunex . Qualified repair shop . Code's stored in 4X4 control module. Need a factory or some other professional scan tool to read code's .
SECTION 308-07A: Transfer Case - General Information
2000 Explorer/Mountaineer Workshop Manual
DESCRIPTION AND OPERATION
Procedure revision date: 06/17/1999
Transfer Case -Automatic Four Wheel Drive (A4WD)
The A4WD system is an electronic shift 4x4 system that allows the operator to choose between three different 4x4 modes. The operator can switch between A4WD and 4WD HIGH modes at any speed. To engage or disengage LOW range, the vehicle speed must be less than 5 km/h, the brake depressed, and the transmission must be in NEUTRAL.
The front/rear driveshaft speed sensors (Hall effect) are mounted to the transfer case and detect the speed of the front and rear driveshafts. This input is used by the generic electronic module (GEM) primarily to control A4WD operation.
The throttle position output signal is provided to the GEM from the powertrain control module (PCM). This signal is used by the GEM in controlling the A4WD clutch.
The shift motor sense plate, an integral part of the electric shift motor, informs the GEM to the position of the transfer case.
The digital TR sensors are located on the LH side of the transmission; these sensors inform the GEM when the transmission is in the neutral position.
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 HIGH range (A4WD, 4HIGH) and LOW range positions.
The 4x4 shift motor uses a module containing two relays which, under the control of the GEM, shifts the transfer case shift motor between HIGH range (A4WD, 4HIGH), and 4LOW modes.
The solid state clutch relay is used to activate the A4WD clutch within the transfer case.
System Function
Hall effect sensor monitors input and output shaft speed.
In the A4WD (C-Trac) system, the GEM varies the torque sent to the front driveline by controlling the transfer case clutch. At rest and under cruising conditions, the GEM activates the transfer case clutch a minimum duty cycle (percentage of time the clutch is turned on), which allows for the slight difference between the front and rear driveshafts which normally occurs when negotiating a corner on dry pavement. Under any of the following conditions, the GEM will increase the duty cycle in order to prevent or control slip:
Feature inputs:
Feature outputs:
Shifts between A4WD and 4x4 HIGH can be made at any speed. Listed below are the inputs and outputs needed by the GEM to execute a change between any of these modes.
Feature inputs:
Feature outputs:
When shifting into or out of LOW range, the GEM 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:
Feature outputs:
Tunex won't have a clue .
P1804 4WD High Indicator Circuit Failure GEM GO to Pinpoint Test C .
P1806 4WD High Indicator Short to Battery GEM GO to Pinpoint Test C .
P1808 4WD Low Indicator Circuit Failure GEM GO to Pinpoint Test C .
P1810 4WD Low Indicator Short Circuit to Battery GEM GO to Pinpoint Test C .
P1812 4WD Mode Select Circuit Failure GEM GO to Symptom Chart.
P1815 4WD Mode Select Short Circuit to Ground GEM GO to Symptom Chart.
P1820 Transfer Case CW Shift Relay Coil Circuit Open or Short to Ground GEM GO to Pinpoint Test B .
P1822 Transfer Case CW Shift Relay Coil Short to Battery GEM GO to Pinpoint Test B .
P1824 4WD Electric Clutch Relay Circuit Failure GEM GO to Pinpoint Test A .
P1826 4WD Electric Clutch Relay Short to Battery GEM GO to Pinpoint Test A .
P1828 Transfer Case CCW Shift Relay Circuit Failure GEM GO to Pinpoint Test B .
P1830 Transfer Case CCW Shift Relay Coil Short to Battery GEM GO to Pinpoint Test B .
P1836 Transfer Case Front Shaft Speed Sensor Circuit Failure GEM GO to Symptom Chart.
P1837 Transfer Case Rear Shaft Speed Sensor Circuit Failure GEM GO to Symptom Chart.
P1838 Transfer Case Shift Motor Circuit Failure GEM GO to Pinpoint Test B .
P1846 Transfer Case CONTACT PLATE "A" Circuit Failure GEM GO to Pinpoint Test B .
P1850 Transfer Case CONTACT PLATE "B" Circuit Failure GEM GO to Pinpoint Test B .
P1854 Transfer Case CONTACT PLATE "C" Circuit Failure (GEM Only) GEM GO to Pinpoint Test B .
P1858 Transfer Case CONTACT PLATE "D" Circuit Failure (GEM Only) GEM GO to Pinpoint Test B .
P1866 Transfer Case Maintenance Required (GEM Only) (4-wheel drive operation can be restored by clearing the DTC and cycling the ignition.) GEM GO to Pinpoint Test B .
P1867 Transfer Case Contact Plate General Circuit Failure (GEM Only) GEM GO to Pinpoint Test B .
P1874 Automatic Hall Effect Sensor Power Circuit Failure GEM GO to Symptom Chart.
P1875 Automatic Hall Effect Sensor Power Circuit Short to Battery (GEM Only) GEM GO to Symptom Chart.
P1891 Transfer Case Contact Plate Ground Return Open Circuit GEM GO to Pinpoint Test B .
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SOURCE: How do you install a 4x4 control module for a 2004 Ford Explorer.
do you mean the elect. control module if so it is behind the radio youll will need the radio tools to take the radio out they can be found at most any parts stores.
SOURCE: cannot connect the negative battery terminal without spark or starter turning over
You will need new igniton cylinder. Sounds like you have a short in the cylinder.
SOURCE: 02 Ford Explorer XLT 4x4 High light flashes and
I had same problem on my 2002 explorer. Its either the computer module, or the electric solenoid on the transfer case. In my case it was both. The computer module I had done twice in 14 months.
SOURCE: 2002 Ford Explorer passenger power window problem
Check the fuse panel first, after that check your fuse relays under the hood, if not then it might be a wiring problem.
Check out F150OwnersBlog.com or 4x4Owners Blog. It sounds like the actuator inside the transfer case is stuck.
If this is the Vacuum shift setup, the plunger inside the 4x4 box is sticking. You also could have low vacuum pressure from a bad Vacuum pump on the engine.
The Electric setups worked differently. The voltage running to the underside wires to the shift solenoid had set values to extend and retract the solenoid plunger. Often, a burned out light in the inside Selector switch on the dash would affect the Voltage sent to the solenoid. A silly thing like changing the indicator bulb would restore the proper voltage underneath the truck.
Remember to sequence the trans to neutral before engaging some of the transfer cases.
I hope my solution is helpful.
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