SOURCE: 4x4 won;t ingage,2000 chevy tracker
Hi Wayne how's it going ? Here is a
Transfer Case Circuit Description ! then I will get into some possibility's of what could be wrong !
There are two main components for the four wheel drive. The powertrain control module (PCM) and the front drive axle actuator pump. The pump is controlled by the PCM. The pump compresses air to engage the front axle. When the transfer case is in four wheel drive (4H or 4L), the four wheel drive switch closes providing a ground signal to the PCM. The PCM actuates the pump which pressurizes the actuator in the front axle. This pressure engages the axle hub which connects the front drive shaft to the axle shafts, allowing the transmission/transfer case to turn the front wheels. The PCM will not operate the pump for more than 10 seconds in order to protect it. The PCM will also provide a path to ground for the 4WD indicator in the instrument cluster. The indicator is provided battery voltage when the ignition switch is in the ON or START position through the IG fuse. With power and ground supplied, the indicator lights.
When the transfer case is in 4L (with auto trans), the four wheel drive low switch sends a ground signal to the PCM. The PCM will not engage the torque converter clutch while this signal is being received.
When the transfer case is returned to the two wheel drive mode, the release valve in the pump opens and releases the pressure in the actuator. Without pressure, the hub disengages.The PCM also releases the ground to the 4WD indicator which causes the indicator to turn off.
Does the four-wheel drive indicator light with 4x4 engaged ?
DEFINITION: The 4WD indicator does not illuminate with 4WD engaged. All other engine and transmission functions are normal. Refer to: Electric Motor and Actuator Check in Driveline/Axle-Front Axle (w/diff).
The next step of testing the electric motor an actuator involve a lot of steps an a special tool -
J 43846 Actuator Pressure Gauge
This a factor diagnostic flow chart , I'm not familiar with the in's an out's of this system , the most probable thing's that go wrong with this system. If you want I can send you the diagnostic flow chart !
Electric Motor and Actuator Check
Tools Required
J 43846 Actuator Pressure Gauge
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When applying pressure to the actuator pump the other front wheel should turn in the direction opposite to the wheel being turned by hand.
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When the actuator pump is not working (by not applying pressure) the other front wheel should remain stationary while the wheel turned by hand is turning.
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Install the actuator pressure gauge to the actuator pump assembly (1) .
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Install a voltmeter and the battery to the pump assembly (1) .
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Tighten the adjusting knob as far as it will stop and the air check side opening by a hose as a blind plug.
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Check that the actuator assembly motor starts to run (a running sound can be heard) when the battery is connected and when it stops when specified pressure is obtained. Specified pressure is: 38.0- 58.0 kPa (5.40 -- 8.25 psi).
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Ensure that the voltmeter is within specifications when the motor is running should be about 0v and when the motor has stopped it should be about 10 -- 14v
good luck !
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