• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
B+ | U1821* | U1821 | -- | -- |
Ground | -- | U1821* | -- | -- |
PTLAN + | U0074* | U1821, 1 | U0074* | -- |
PTLAN - | U0074* | U1821, 1 | U0074* | -- |
* Other modules/DTCs may set with this fault. 1. Multiple DTCs including U1821 may set and multiple symptoms including a no start condition may occur. |
Modules connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.
DTC U1821 will set in the drive motor generator power inverter module when no communication is established with the accessory DC power control module on the PTLAN serial data bus.
• | The system voltage is between 9-16 volts. |
• | The vehicle power mode master requires serial data communication to occur from this specific module. |
A supervised periodic message that includes the transmitter module availability has not been received.
The modules is never signaled, therefore the specific subsystems will not function.
• | 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. |
Different DTCs may set in different modules along with this DTC depending on where the fault occurs and the vehicle operating conditions when the fault occurs.
Data Link Communications Description and Operation
EL-48900 HEV Safety Kit
Verify DTC U182A is not set in the serial data gateway module (SDGM).
⇒ | If the DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle to diagnose that DTC prior to this diagnostic. |
Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.
The High Voltage Disabling procedure will perform the following tasks:• | Identify how to disable high voltage. |
• | Identify how to test for the presence of high voltage. |
• | Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed. |
⇒ | If greater than the specified value, test the ground circuit for an open/high resistance. |
⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
• | Accessory DC power control module terminal 1 and drive motor generator power inverter module terminal 24 |
• | Accessory DC power control module terminal 2 and drive motor generator power inverter module terminal 25 |
⇒ | If greater than the specified value, test the serial data circuits for an open/high resistance. |
⇒ | If less than the specified value, test the serial data circuits for a short between the circuits. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for module replacement, setup, and programming |