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Check connection at the 4X4 control module , check power and grounds . Do you know how to do basic electrical testing ? Does your truck have manual or automatic trans mission ? Which transfer case does yours have ?
The NVG 263 transfer case features a three button shift control switch located on the instrument panel. When the ignition is in the RUN position, the transfer case shift control module (TCCM) starts monitoring the transfer case shift control switch to determine if the driver desires a new mode/gear position. At a single press of the transfer case shift control switch, the lamp of the new desired position begins flashing to inform the driver that the TCCM has received the request for a new mode/gear position. The lamp continues to flash until all shifting criteria has been met and the new mode/gear position has been engaged. Once the new mode/gear position is fully active, the switch indicator for the new position remains ON constantly. In the event that the TCCM can not or will not complete the shift, the indicator returns to the previously selected position; this is a Transfer Case Shift Control Switch Indicator Flashes, then Returns to Previous Mode condition.
The NVG 263 transfer case provides the driver with 4 manual mode/gear positions:
• 2HI - 2 Wheel Drive high range
• 4HI - 4 Wheel Drive high range
• 4LO - 4 Wheel Drive low range
• Neutral
Have it check for DTC'S - diagnostic trouble codes ?
The 4X4 system on your vehicle is computer controlled , GEM module . generic electronic module . The four wheel drive mode switch is a low voltage input to the GEM module . The GEM energizes relay's to control the mode as depicted by input from the mode switch an torque on demand relay an someother inputs . Probably has DTC - diagnostic trouble codes stored in the GEM module .
Transfer Case -Automatic Four-Wheel Drive (A4WD)
The automatic 4-wheel drive transfer case system consists of the following:
automatic 4WD indicator light
brake pedal position (BPP) switch
torque on demand (TOD) relay
front output shaft speed sensor
generic electronic module (GEM)
4WD high indicator light
4WD low indicator light
4WD mode switch
rear output shaft speed sensor
shift position sensor
throttle position output (TPO) from the powertrain control module (PCM)
transmission range sensor
P1804
Transmission 4-Wheel Drive High Indicator Circuit Failure
GEM
REFER to Section 413-01 .
P1806
Transmission 4-Wheel Drive High Indicator Short Circuit to Battery
GEM
REFER to Section 413-01 .
P1812
Transmission 4-Wheel Drive Mode Select Circuit Failure
GEM
REFER to the Symptom Chart.
P1815
Transmission 4-Wheel Drive Mode Select Short Circuit to Ground
GEM
GO to Pinpoint Test C .
P1820
Transmission Transfer Case Clockwise Shift Relay Coil Circuit Failure
GEM
GO to Pinpoint Test B .
P1822
Transmission Transfer Case Clockwise Shift Relay Coil Short Circuit to Battery
GEM
GO to Pinpoint Test B .
P1824
Transmission 4-Wheel Drive Clutch Relay Circuit Failure
GEM
GO to Pinpoint Test A .
P1826
Transmission 4-Wheel Drive Low Clutch Relay Circuit to Battery
GEM
GO to Pinpoint Test A .
P1828
Transmission Transfer Case Counter Clockwise Shift Relay Coil Circuit Failure
GEM
GO to Pinpoint Test B .
P1830
Transmission Transfer Case Counter Clockwise Shift Relay Coil Short Circuit to Battery
GEM
GO to Pinpoint Test B .
P1836
Transmission Transfer Case Front Shaft Speed Sensor Circuit Failure
GEM
GO to Pinpoint Test A .
P1837
Transmission Transfer Case Rear Shaft Speed Sensor Circuit Failure
GEM
GO to Pinpoint Test A .
P1838
Transmission Transfer Case Shift Motor Circuit Failure
GEM
REFER to the Symptom Chart.
P1846
Transmission Transfer Case Contact Plate 'A' Circuit Failure
GEM
REFER to the Symptom Chart.
P1850
Transmission Transfer Case Contact Plate 'B' Circuit Failure
GEM
REFER to the Symptom Chart.
P1854
Transmission Transfer Case Contact Plate 'C' Circuit Failure
GEM
REFER to the Symptom Chart.
P1858
Transmission Transfer Case Contact Plate 'D' Circuit Failure
GEM
REFER to the Symptom Chart.
P1866
Transmission Transfer Case System Concern - Servicing Required
GEM
REFER to the Symptom Chart.
P1867
Transmission Transfer Case Contact Plate General Circuit Failure
GEM
REFER to the Symptom Chart.
P1874
Transmission Automatic Hall Effect Sensor Power Circuit Failure
GEM
GO to Pinpoint Test A .
P1875
Transmission Automatic Hall Effect Sensor Power Circuit Short to Battery
GEM
REFER to the Symptom Chart.
P1891
Transmission Transfer Case Contact Plate Ground Return Open Circuit
GEM
REFER to the Symptom Chart.
P1892
Trans. Automatic 4-Wheel Drive 4X4 Mechanical Lock Output Circuit Failure
GEM
GO to Pinpoint Test B .
P1893
Trans. Auto. 4-Wheel Drive 4X4 Mechanical Lock Output Short to Battery
GEM
GO to Pinpoint Test B .
Your best bet , take it to a qualified repair shop .
Which of these does your vehicle have ?
The NVG 233 transfer case features a 3 button shift control switch, located on the instrument panel.
The NVG 236 transfer case features a 4 button shift control switch located on the instrument panel.
Do you know what DTC'S - diagnostic trouble codes are ? Both of these 4X4 systems can set DTC'S , Having a professional or factory scanner is what is needed to check for these codes . Not a OBD 2 code reader or autozone , advance etc... The four button system can set a bunch of them .
DTC B2725
DTC C0300
DTC C0305
DTC C0308
DTC C0309
DTC C0310
DTC C0315
DTC C0323
DTC C0324
DTC C0327
DTC C0362
DTC C0367
DTC C0374
DTC C0376
DTC C0387
DTC C0550
DTC C0611
The NVG 233 transfer case features a 3 button shift control switch, located on the instrument panel. When the ignition is in the RUN position, the transfer case shift control module starts monitoring the transfer case shift control switch, to determine if a new mode/gear position has been selected. At a single press of the transfer case shift control switch, the lamp of the new position begins flashing to inform the driver that the transfer case shift control module has received the request for a new mode/gear position. The lamp continues to flash until all shifting criteria has been met and the new mode/gear position has been reached, or has engaged. Once the new mode/gear position is fully active, the switch indicator lamp for the new position remains ON constantly.
The NVG 233 transfer case provides the driver with 3 manual mode/gear positions:
• 2HI - 2 Wheel Drive high range
• 4HI - 4 Wheel Drive high range
• 4LO - 4 Wheel Drive low range
Any of these mode/gear positions may be selected while driving the vehicle. However, the transfer case will not allow a shift into, or out of, 4LO unless the following criteria has been met:
• The engine is running.
• The automatic transmission is in Neutral, or the clutch pedal is applied on manual transmissions.
• The vehicle speed is below 5 km/h (3 mph).
Finding out what if any codes are stored should be your first step .
I was researching the recalls for the 2002 tundra and havent found any recall pertaining to the 4whl drive. Sometimes when people have their 4wheel drive locked in and drive on pavement for any length of time, whether it be just a couple of feet or a couple of miles, over time it creates a binding of the gears in your transfer case. Once the bind is so great, the engaging and disengaging starts malfunctioning and leads to bigger problems overall. I could be wrong about this being the problem that you have but I think its something to look into. It wouldnt hurt to put your vehicle up off all fours and release the bind if any by running through the gears while in 2 and rour wheel drive while all four tires can move freely and release. See if that works for you. Check your gear oil front , center and rear and use much caution when attempting this suggestion. Also refer to your owners manual troubleshooting section for other possibilities. Merry Christmas. By the way, the electrical switch should be covered in the troubleshooting section also.
Hi, it sounds like your front diff engages but your transfer case is not. raise one of your front tires off the ground and see if it will lock up when you go to 4hi. If it does then the problem is your encoder motor that hangs down under your transfer case.
Probably becuse when selling the vehicle 4-wheel drive had a problem and the vacuum is what switches into 4-wheel mode.The lights would come on indicating 4x4 on.and without lifting vehicle off the ground you couldnt tell. An old trick of the trade. ?
I had this same problem a few years ago. In my case I didn't use the 4 Wheel Drive very often and the tranfer would hang in 2 Wheel. I fixed mine by tapping on the transfer case with a hammer while my wife switched back and forth from 2 Wheel to 4 Wheel.
this switch does not switch the vehicle from 2 wheel to 4 wheel drive. Grand cherokee have a manual shifter for that. The 4x4 switch is on top of the transfer case and tells the driver information display what 4 wheel drive mode the Jeep is in. ex..if you have selectrac, in 2 wheel the rear wheels on the display will light up, in 4 wheel all 4 wheels will light up, in 4 wheel low it will have the word low lit up in yellow. This is the only purpose for this switch and a bad one will not affect the functioning of the 4 wheel drive. Check out Rockauto.com and a new one can be purchased for about 35 dollars. If you call the dealership and ask for a 4 wheel drive switch, they will have no clue what you are talking about. The actual name is " 4WD indicator light switch"
Just to clarify, the "transmission" is not stuck in 4-Lo. It is the "transfer case" that is attached to the transmission that actually engages the 4-Hi and 4-Lo modes. To properly shift your vehicle into 4-Lo, you know that you have to shift the transmission into neutral and slow down to less than 5 mph. Once your vehicle slows down to this range, your can switch your transfer case into 4-Lo mode. Due to the inner workings of the transfer case, the actual shift into 4-Lo may take a few seconds to complete. This is normal and does not signify that there is an issue. All transfer cases that have 4-Lo mode will act this way regardless of the make or model. To make a long story short, to shift out of 4-Lo you must follow the same steps that you took to shift into 4-Lo, just in reverse order. Switch the transfer case to 4-Lo mode if it isn't already there. Slow down to less than 5 mph (your vehicle must be moving, though). Then, shift your car into 4-Hi or 2WD. Give your vehicle several seconds to complete the shift. The transfer case indicator light will flash until it is complete. When it does complete the shift into the new gear mode, you will most likely hear a "clunk" (the range sleeve inside the transfer case disengages from its mating spline) from under your car. Again, any transfer case with 4-Lo (regardless of make or model) will exhibit this same noise. This should help you get out of 4-Lo. It is good practice to shift your car into and out of 4-Lo at least a few times each year to keep all of the splines free of corrosion and build-up. Based on the age of your vehicle, your transfer case may also need a complete flush and some new transmission fluid. Hope this helps.
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