DTC U18B9-U18BF
Diagnostic Instructions
DTC Descriptor
DTC U18B9: Primary High Speed CAN Bus Subnet
Configuration List |
DTC U18BF: Secondary High Speed CAN Bus Subnet
Configuration List |
Circuit/System Description
Control modules on the high speed GMLAN serial data bus and the
chassis high speed GMLAN serial data bus must be programmed with
software that specifically identifies the correct type and quantity
of modules on the bus based on RPO configuration. If a control
module was not properly configured after installation, the
appropriate U Code may be set for that module. No external circuit
diagnosis is involved.
Conditions for Running the DTC
• |
Voltage supplied to the module
is in the normal operating voltage range. |
• |
The vehicle power mode
requires serial data communication to occur. |
Conditions for Setting the DTC
• |
The control module is not
configured properly. |
• |
Control unit recognises a
programming error. |
• |
CAN-Bus configuration is
invalid |
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, without
a repeat of the malfunction. |
Reference Information
Schematic Reference
Data Communication Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Data Link Communications Description and Operation
Electrical Information Reference
Scan Tool References
Control Module References for scan tool information
Circuit/System Verification
1. |
Verify the appropriate DTC is
not set. |
⇒ |
If the DTC is set along with other codes, diagnose
all other codes first. If no other codes are set, program the
control module that set the DTC. |
2. |
With a scan tool, clear the
DTCs. |
3. |
Ignition OFF, remove the scan
tool, open and close the drivers door. |
4. |
Wait 60 seconds, then verify
the DTC is not set. |
⇒ |
If the DTC is set, replace the appropriate control
module. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
Control Module References for control module replacement,
setup, and programming
|