Circuit Description
The Vehicle Control Module (VCM)/Powertrain Control Module (PCM) monitors the serial data (class II) circuit for communications from the Automatic Transfer Case (ATC) controller. If the ATC controller is not communicating with the VCM this DTC will set.
Conditions for Setting the DTC
No serial data (class II) from ATC controller to the VCM/PCM.
Action Taken When the DTC Sets
This DTC will not illuminate the MIL.
Conditions for Clearing the MIL/DTC
| • | A History DTC will clear after 40 consecutive warm up cycles with no failures of any non-emissions related diagnostic test. |
| • | VCM/PCM battery voltage is interrupted. |
| • | Use of a scan tool. |
Diagnostic Aids
This DTC will not set unless the VCM/PCM and ATC controllers have already establish communications first.. This DTC will only diagnosis an open or intermittent connection from the ATC controller to the splice.
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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This test checks if communication can be established between the scan tool and the ATC Control Module. If the scan tool cannot communicate with the ATC Control Module, refer to the ATC Control Module System Check.
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This test checks for any opens in the Class 2 Serial Data circuit between the VCM and the ATC Control Module. It also checks for any intermittent malfunctions associated with the serial data circuit.
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Use a scan tool to clear and check for any DTCs in all the modules connected to the Class 2 Serial Data circuit (VCM/PCM, ATC, and EBCM).
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear DTC Information function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Powertrain On Board Diagnostic (OBD) System Check (5.0L/5.7L), Powertrain On Board Diagnostic (OBD) System Check (6.5L), Powertrain On Board Diagnostic (OBD) System Check (7.4L) in Engine Controls | |||||||||
Does the scan tool communicate with the Transfer Case Shift Control Module? | -- | |||||||||||
Check the Class 2 Serial Data circuit for the following intermittent conditions:
Did you find a problem? | -- | |||||||||||
4 |
Does DTC U1026 reset? | -- | ||||||||||
5 | This DTC is intermittent. Are any additional DTCs stored? | -- | -- | |||||||||
6 | Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||||
Are any DTCs displayed? | -- | System OK |
