Good evening,
The 700 is a general code for the transmission indicating there are other codes. The 73 is a communication issue.
https://www.2carpros.com/articles/automatic-transmission-problems
Can you communicate with the transmission control module. The most common issue is dirty connections at the connectors for the module. I posted the location of the module for you below.
Roy
GM has several TSB with similar symptoms.
08-07-30-021H: Loss of High Speed GMLAN Communications, Intermittent No Crank, IP Gauge Fluctuation, Intermittent Door Lock Cycling / Chime Operation, Various IP Warning Lamps Illuminated, Transmission May Not Shift, Communication DTCs U0073, U0100, U0101, U0102, U0109, U0121 or U0140 Set - (Jun 25, 2015) in ALLDATA
1. PIT4667D: Diagnostic Tips - Diagnosing High Speed LAN Concerns - (Jul 13, 2015) in ALLDATA Community
2. TSB 08-07-30-021H: Loss of High Speed GMLAN Communications, Intermittent No Crank, IP Gauge Fluctuation, Intermittent Door Lock Cycling / Chime Operation, Various IP Warning Lamps Illuminated, Transmission May Not Shift, Communication DTCs U0073, U0100, U0101, U0102, U0109, U0121 or U0140 Set - (Jun 25, 2015) in ALLDATA
4. PIT4730A: Additional Diagnostic Information For U0140 Or U0073 - keywords comm DIC gage gauge inop inoperative int lan message speedo start tach - (Jun 18, 2010) Library request
5. PIT3993C: No Crank / No Start At Times - keywords code communication DTC high lan speed U0100 U0101 U0102 U0140 U2100 U0073 - (Nov 7, 2007) in ALLDATA Community
73
DTC U0073 or U2100
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. See: Vehicle > Initial Inspection and Diagnostic Overview
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC U0073 00
Control Module Communication Bus Off
DTC U0073 71
ECU HS Bus Off
DTC U0073 72
ECU LS Bus Off
DTC U2100 00
Controller Area Network (CAN) Bus Communication
DTC U2100 47
Controller Area Network (CAN) Bus Communication
Circuit/System Description
The serial data circuits are serial data buses are used to communicate information between the control modules. The serial data circuits also connect directly to the data link connector (DLC).
Conditions for Running the DTCs
Supply voltage at the modules are in the normal operating range.
The vehicle power mode requires serial data communications.
Conditions for Setting the DTC
The module setting the DTC has attempted to establish communications on the serial data circuits more than 3 times.
Action Taken When the DTCs Sets
The module suspends all message transmission.
The module uses default values for all parameters received on the serial data circuits.
The module inhibits the setting of all other communication DTCs.
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.
Circuit/System Verification
1. Refer to Data Link References to determine which serial data system is used for a specific module. See: Information Bus > Initial Inspection and Diagnostic Overview > Data Link References
2. This DTC cannot be retrieved with a current status. Diagnosis is accomplished using the symptom Scan Tool Does Not Communicate with High Speed GMLAN Device or Scan Tool Does Not Communicate with Low Speed GMLAN Device.
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Saturday, November 21st, 2020 AT 4:22 PM