Circuit Description
The front transfer case propshaft speed sensor generates the Front Propshaft Speed as shown by the scan tool. The front transfer case propshaft speed sensor is a Permanent Magnet (PM) generator. The PM generator produces a pulsing AC voltage. The AC voltage level and number of pulses increases as speed increases. The transfer case shift control module converts the pulsating AC voltage from the vehicle speed sensor to Front Propshaft Speed in RPM to be used for calculations, and to monitor the difference between the front and rear sensor speed. It is also used in the AUTO (Adapt) mode of operation to determine the amount of slip and the percent of torque to apply to the front axle. The Front Propshaft Speed can be displayed with a scan tool.
This DTC detects an open, short to ground, or faulty sensor.
Conditions for Setting the DTC
The system will log the DTC if the Front Propshaft Speed input indicates a speed of less than 16 RPM for 30 seconds while all of the following are true:
| • | Transmission NOT in PARK or NEUTRAL |
| • | Engine is running |
| • | Rear Propshaft Speed exceeds 512 RPM |
| • | VCM monitored Vehicle Speed on the Class 2 Data bus exceeds 10 mph |
Action Taken When the DTC Sets
The system will not allow any further adaptive events (correct slip). The SERVICE AWD/4WD lamp will be latched on for the remainder of the current ignition cycle.
Conditions for Clearing the DTC
| • | Current DTC |
| The transfer case shift control module will clear the DTC if the condition for setting the DTC no longer exists. |
| • | History DTC |
| - | Once 100 consecutive ignition cycles without a fault present. |
| - | A scan tool CLEAR CODES command. |
Diagnostic Aids
An intermittent problem may be caused by a poor connection, break in the wire insulation exposing the internal wire, or a wire that is broken inside the insulation.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Transfer Case Diagnostic System Check performed? | -- | ||
2 |
Were there any DTCs found? | -- | ||
3 |
Are the rpm values within 10 percent of each other at the same speeds? | -- | ||
4 |
Does the voltage vary between the specified values? | 0-0.5 V AC | ||
5 |
Is the resistance reading within the specified values? | 1300-2700 ohms | ||
6 | Measure the resistance between transfer case shift control module connector C1 terminals E12 and E13. Is the resistance reading within the specified value? | OL | ||
7 |
Is the voltage within the specified value? | 0 V | ||
8 | Measure the resistance between the transfer case shift control module connector C1 terminal E12 and ground. Is the resistance reading within the specified value? | OL | ||
9 | Measure voltage between the transfer case shift control module connector C1 terminal E13 and ground. Is the voltage within the specified value? | 0 V | ||
10 | Measure the resistance between the transfer case shift control module connector C1 terminal E13 and ground. Is the resistance reading within the specified value? | OL | ||
11 | Measure the resistance between the transfer case shift control module connector C1 terminal E12 and front vehicle speed sensor terminal A. Is the resistance reading within the specified value? | 0-5 ohms | ||
12 | Measure the resistance between the transfer case shift control module connector C1 terminal E13 and the front vehicle speed sensor terminal B. Is the resistance reading within the specified value? | 0-5 ohms | ||
13 | Repair an open in CKT 400 between the vehicle speed sensor and the transfer case shift control module. Are the repairs complete? | -- | -- | |
14 | Repair an open in CKT 401 between the vehicle speed sensor and the transfer case shift control module. Are the repairs complete? | -- | -- | |
15 | Repair a short between CKT 400 and CKT 401. Is the repair complete? | -- | -- | |
16 | Repair a short to voltage condition in CKT 400. Are the repairs complete? | -- | -- | |
17 | Repair a short to ground condition in CKT 400. Are the repairs complete? | -- | -- | |
18 | Repair a short to voltage condition in CKT 401. Are the repairs complete? | -- | -- | |
19 | Repair a short to ground condition in CKT 401. Are the repairs complete? | -- | -- | |
20 | Replace the transfer case shift control module. Refer to Transfer Case Control Module Replacement. Is the action complete? | -- | -- | |
21 | Replace the front speed sensor. Refer to Front Speed Sensor Replacement. Is the action complete? | -- | -- | |
22 | Reconnect all ATC system components, make sure all the components are properly mounted. Have all the ATC components been reconnected and properly mounted? | -- | -- | |
23 | Clear all the ATC codes. Are all the ATC codes cleared? | -- | -- |
