3. Ignition ON, verify that a test lamp illuminates between the following voltage circuit terminals of the PIM and ground.
* Terminal 6
* Terminal 7
* Terminal 20
锟斤拷If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance.
4. Ignition ON, verify that a test lamp illuminates between the signal circuit terminal 19 and ground.
锟斤拷If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the
SDGM.
5. Ignition OFF, disconnect the harness connector X3 at the engine control module.
6. Test for less than 1.0 ohm on the high speed hybrid GMLAN serial data circuits between the following ECM and PIM circuit terminals.
* ECM X 3 terminal 53 and PIM X 1 terminal 11
* ECM X 3 terminal 33 and PIM X 1 terminal 10
锟斤拷If greater than the specified range, test the circuit for open/high resistance
7. If all circuits test normal, replace the PIM.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for module replacement, setup, and programming
U1817
DTC U1817
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC U1817 00
- Lost Communication With Hybrid Powertrain Control Module on Bus "B"
Diagnostic Fault Information
Circuit/System Description
Modules connected to the PTLAN 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.
Conditions for Running the DTC
* The system voltage is between 9-16 volts.
