My four wheel drive problem

There could be a few possible causes for your 2002 Chevrolet Tahoe not going into four-wheel drive when you engage the system. Some common issues include:

The four-wheel drive system may not be properly engaged. Make sure that the four-wheel drive switch is in the correct position and that you are following the proper procedure for engaging the system.

The four-wheel drive system may be mechanically damaged. This could be caused by a problem with the transfer case, the drive axles, or other components of the system.

There may be a problem with the four-wheel drive system's control module or other electrical components.

There may be a problem with the four-wheel drive system's vacuum lines or other mechanical components.

To troubleshoot the issue, you can try the following steps:

Check the four-wheel drive switch and make sure it is in the correct position.

Check the four-wheel drive system's control module and make sure it is functioning properly.

Check the four-wheel drive system's vacuum lines and make sure they are not damaged or disconnected.

If the issue persists, it may be necessary to have the vehicle inspected by a qualified mechanic.

If you are not comfortable performing these steps, or if the issue persists after trying these troubleshooting steps, it may be a good idea to contact a mechanic or a Chevrolet dealership for further assistance.

I got this free Pdf man ual from reliable-store for free and I don't think Ive visited a mechanic or fixya for help for more than 3-4 times out of the 20 times I fixed the chipper in these 4 years

nothing to do with light ,think its mechanical like a wheel loose or a drive shaft .rear wheel drive or front wheel drive ? symptoms different if rear wheel drive then maybe a propshaft UJ ,if front wheel drive then maybe deformed tyres

They are on the transmission under the truck. One is usually by the tail shaft and the other should be a few inches away from it. They are both two wire sensors I believe.

all wheel drive is four wheel drive , i think you mean back to 2 wheel drive , no way to bypass the four drive switch , have to take to a transmission specialist

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 .

If you are the Calvin DeGreenia I'm thinking you are, and still have not had your questioned answered, you should call and ask your father. He is an excellent mechanic. Best of luck to you.

There is a four wheel drive relay unit located up under your dashboard on the passenger's side that has gone bad. 2 bolts hold it in, and just a wire bundle connector to plug into. Costly to replace. Maybe about $200 just for the 4 WD relay unit.

If the Tires wont spin then it isnt locked in.
If it really is engaged like you think it is and they dont turn then something is broken in the differential. If that was the case then it should be makeing lots of noise.
Now it is very very common for the electro-mechanical device that engages the the 4wheel drive at the differential to go bad. If you look at the front differential you cant miss the 4 wheel drive actuator. It has a couple wires that come out and plug into the wiring harness.
Usually if this part fails I understand the 4wheel drive indicator lights wont come on? I could be wrong on that. My sub is 3 years older and that was the case with it.

well there maybe some internal damge on the case these are horible transfer cases, a fork broke in mine making the case slip, check the encoder motor to make sure its working