Circuit Description
The front axle control circuit consists of an electric motor actuator which engages and disengages the front axle. The front axle actuator's motor consists of a Permanent Magnetic (PM) motor, a worm gear controlled plunger, a front axle switch and an electronic control circuit all within the actuator assembly.
The front axle actuator has four circuits connected to it. Circuit 241 supplies ignition voltage to the actuator. Circuit 2150 provides the ground. Circuit 1695 is the front axle switch, and circuit 1570 is the front axle control.
Whenever a shift to AUTO, 4WD, 4HI, or 4LO is requested, the automatic transfer case control module engages the front axle by grounding the front axle control circuit 1570 through a current limiting driver.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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This step determines if the front axle actuator has a good power and ground supplied to it.
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This step determines if the transfer case shift control module is providing the ground signal to the front axle actuator through terminal B in order to drive the front axle actuator motor.
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This step determines if the transfer case shift control module is able to sense voltage on CKT 1695.
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This step determines if the front axle switch is suppling power to the transfer case shift control module.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Transfer Case Diagnostic System Check performed? | -- | Go to Step 2 | |
2 |
Does the Scan Tool show the Front Axle Switch status Locked? | -- | Go to Step 6 | Go to Step 3 |
Is the voltage within the value specified? | 9-14 V | Go to Step 4 | Go to Step 12 | |
Is the voltage reading within the specified value? | 9-14 V | Go to Step 5 | Go to Step 17 | |
Does the Scan Tool show the Front Axle Switch status Locked? | -- | Go to Step 20 | Go to Step 10 | |
Does the Scan Tool show the Front Axle Switch status Locked? | -- | Go to Step 8 | Go to Step 7 | |
7 | Inspect the front axle for mechanical concerns, if no mechanical concerns are present replace the Front Axle Actuator. Refer to Electric Motor Actuator Replacement . Is the repair complete? | -- | Go to Step 22 | -- |
8 |
Is the voltage reading within the specified values? | 0-0.5 V | Go to Step 19 | Go to Step 9 |
9 | Repair a short to voltage in CKT 1695. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 22 | -- |
10 |
Is the resistance reading within the specified values? | 0-2 ohms | Go to Step 19 | Go to Step 11 |
11 | Repair open in CKT 1695. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 22 | -- |
12 |
Is the voltage reading within the specified values? | 9-14 V | Go to Step 13 | Go to Step 14 |
13 | Repair open in CKT 2150. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 22 | -- |
14 | Inspect the 4WD fuse in CKT 241 for continuity. Is the fuse good? | -- | Go to Step 15 | Go to Step 16 |
15 | Repair open in CKT 241. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 22 | -- |
16 |
Is the fuse good? | -- | Go to Step 22 | Go to Step 21 |
17 |
Is the resistance reading within the specified values? | 0-2 ohms | Go to Step 19 | Go to Step 18 |
18 | Repair open in CKT 1570. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 22 | -- |
19 | Replace the transfer case shift control module. Refer to Transfer Case Shift Control Module Replacement . Is the action complete? | -- | Go to Step 22 | -- |
20 | Replace the front axle actuator. Refer to Electric Motor Actuator Replacement . Is the action complete? | -- | Go to Step 22 | -- |
21 | Repair short to ground in CKT 241. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 22 | -- |
22 |
Have all the ATC components been reconnected and properly mounted? | -- | Go to Step 23 | -- |
23 | Clear all ATC DTCs. Have all the ATC DTCs been cleared? | -- | -- |
