DTC U1300
CIRCUIT DESCRIPTION
DTC U1300 - U1305
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. Node Alive messages are transmitted by each module on the class 2 serial data circuit about once every 2 seconds. When the module detects one of the following conditions on the class 2 serial data circuit for approximately 3 seconds , the setting of all other class 2 serial communication DTCs is inhibited and a DTC will set.
CONDITIONS FOR SETTING THE DTC s
No valid messages are detected on the class 2 serial data circuit.
The voltage level detected on the class 2 serial data circuit is under one of the following conditions:
High
Low
The above conditions are met for approximately 3 seconds.
ACTION TAKEN WHEN THE DTCS SETS
The module inhibits the setting of all other class 2 DTCs.
The module uses default values for all parameters received on the class 2 serial data circuit.
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.
DIAGNOSTIC AIDS
These DTCs cannot be retrieved with a current status. Diagnosis of current DTCs is accomplished via the symptom. Refer to Scan Tool Does Not Communicate with Class 2 Device. See: Powertrain ManagementComputers and Control SystemsInformation BusTesting and InspectionSymptom Related Diagnostic Procedures
An intermittent condition is likely to be caused by a short or an open on the class 2 serial data circuit. Use the Scan Tool Does Not Communicate with Class 2 Device procedure in order to isolate an intermittent condition.
Circuit Description
Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for state of health monitoring/node alive messages. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an identification number is learned by a module, it will monitor for that modules node alive message. Each module on the class 2 serial data circuit is required to send a Node Alive message every 2 seconds. When no message is detected from a learned identification number for 5 seconds, a DTC U1XXX. XXX is equal to the 3 digit identification number of the module.
The control module ID number list provides a method for determining which module is not communicating. A module with an internal class 2 serial data circuit malfunction or which loses power during the current ignition cycle would have a lost communication DTC set by other modules. Use the control module ID number list in order to determine which module is not communicating and the lost communications with XXX diagnostic table in order to diagnose the malfunction. When no message is detected from a learned identification number for 5 seconds, a DTC U1XXX is set.
Control Module ID Number
Powertrain Control Module (PCM) 016
Transmission Control Module (TCM) 024
Transfer Case Shift Control Module 026
Electronic Brake Control Module (EBCM) 041
Rear Wheel Steering Control Module 048
Body Control Module (BCM) 064
Inflatable Restraint Sensing and Diagnostic Module (SDM) 088
Instrument Panel Cluster (IPC) 096
Radio 128
Audio Amplifier 129
Remote Playback Device-CD Changer 130
Digital Audio Broadcast Module (DAB) 136
Digital Radio Receiver 137
Vehicle Communication Interface Module (VCIM) 151
HVAC Control Module 152
Rear Seat Audio Controller 154
Rear Seat Entertainment (RSE) Assembly 154
Driver Door Module (DDM) 160
Front Passenger Door Module (FPDM) 161
Memory Seat Module (MSM) 166
RSA/HVAC Control Module 167
Theft Deterrent Control Module 192
When more than one loss of communication DTC is set in a single module or among multiple modules, diagnose the DTCs in the following order:
Current DTCs before history DTCs except as specified in the diagnostic tables.
The DTC which is reported the most times.
From the lowest number DTC to the highest number DTC.
Conditions for Running the DTC
Voltage supplied to the module is in the normal operating voltage range of 9-16 volts.
DTCs U1300, U1301 or U1305 do not have a current status.
The vehicle power mode requires serial data communication to occur.
Conditions for Setting the DTC
A node alive message has not been received from a module with a learned identification number within the last 5 seconds.
Action Taken When the DTC Sets
The module uses a default value for the missing parameter.
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.
Diagnostic Aids
An intermittent open between a module and a star connector may cause this DTC to set.
A poor connection at a module or a star connector may cause this DTC to set.
An intermittent open in a star connector may cause this DTC to set.
An open voltage or ground circuit to a module may cause this DTC to set.
An internal module malfunction may cause this DTC to set.
Test Description
The number below refers to the step number on the diagnostic table.
The module which was not communicating on the class 2 serial data circuit may have set Loss of Communication DTCs for those modules that it was monitoring.
i think the u 1300 and 1604 are the key to your issues which basicly come down to the bcm. verify power and grounds to the unit.
try removing the battery cable and re attaching. if all comes back, then definite bcm
Roy
May 13, 2021 at 8:11 PM
(Merged)
