DTC U1845 or U1846
Diagnostic Instructions
DTC Descriptors
DTC U1845 00: Drive Motor Control Module 1 Lost Communication with Hybrid Powertrain Control Module
DTC U1846 00: Drive Motor Control Module 2 Lost Communication with Hybrid Powertrain Control Module
Circuit/System Description
The motor control modules and the hybrid powertrain control module 1 are all internal to the power inverter module. The motor control modules communicate only with the hybrid powertrain control module 1 with the hybrid powertrain control module 1 sending out diagnostic trouble code information to other control modules regarding the motor control modules. All circuits to the hybrid powertrain control module 1 and motor control modules are also internal to the power inverter module and replaced as a single component.
Communication diagnostics for the serial data, including control module power and earth, as well as the wake-up circuits for motor control modules and the hybrid powertrain control module 1, are all diagnosed from external sources only to the power inverter module connector because any circuit fault condition within the power inverter module will cause a complete replacement.
Conditions for Running the DTC
| • | The system voltage is more than 10 V. |
| • | The vehicle power mode master requires serial data communication to occur from this specific module. |
Conditions for Setting the DTC
A supervised periodic message that includes the transmitter module availability has not been received.
Action Taken When the DTC Sets
The control module is never signalled. Therefore, the specific subsystems will not function.
Conditions for Clearing the DTC
| • | A current DTC clears when the malfunction is no longer present. |
| • | A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction. |
Diagnostic Aids
| • | Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U-code present. However, there is no associated "current" or "active" status. Loss-of- communication U-codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios: |
| - | A control module on the data communication circuit was disconnected while the communication circuit is awake. |
| - | Power to one or more control modules was interrupted during diagnosis. |
| - | A low battery condition was present, so some control modules stop communicating when battery voltage drops below a certain threshold. |
| - | Battery power was restored to the vehicle and control modules on the communication circuit did not all re-initialise at the same time. |
| - | If a loss-of-communication U-code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part. |
| • | A control module may have a U-code stored in history that does not require any repairs. Issues with late or corrupted messages between control modules can be temporary with no apparent symptom or complaint; this does not mean the control module is faulty. Do not replace a control module based only on a history U-code. |
| • | The control module may not have internal protection for specific control circuits and may open a B+ or ignition fuse. If a fuse is open and the B+ or ignition circuit is not shorted to earth, ensure none of the control circuits are shorted to earth before replacing the non communicating control module. |
| • | If DTC U1845 or U1846 is only set current in the hybrid powertrain control module 1, the power inverter module must be replaced due to all circuits between the hybrid powertrain control module 1 and motor control modules being internal to the power inverter module. |
Reference Information
Schematic Reference
Connector End View Reference
Component Connector End Views
Description and Operation
Data Link Communications Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Verify that DTC U0293 is not set.
- Verify that DTC U1845 or U1846 is not set current only in the hybrid powertrain control module 1.
| ⇒ | If any of the DTCs are set current in the hybrid powertrain control module 1 only, replace the T6 power inverter module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
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