Code
U1192
HUMMER
U — Network/User
Loss of VTD Class 2 Serial Data Com
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring on the Class 2 serial data circuit to the VTD module
- Poor or missing ground at the VTD or related modules
- Corroded, loose, or damaged connector(s) at the VTD module or splice
- Failed VTD module
- Bus contention from another device (shorted data line)
- Aftermarket equipment tapped into the Class 2 bus causing interference
Symptoms
- Stored U1192 and possibly other network/communication U-codes
- Loss or intermittent operation of functions that rely on the VTD module
- Security/indicator lamp illumination or unexpected status messages
- Modules listed as 'not responding' or 'missing' on a scan tool
What to check
- Connect a factory-level scan tool; read U1192 and any other network or module communication codes and freeze frame data
- Note which modules are reporting on the Class 2 bus and which are missing
- Visually inspect wiring, connectors and splices to the VTD module for corrosion, bent pins, separations or water intrusion
- Check battery and charging system voltage (stable nominal voltage) while scanning
- Check module and chassis ground points associated with the VTD and Class 2 network
- Disconnect aftermarket accessories that may be tied into vehicle data or power circuits
Signal parameters
- Class 2 serial data line should be continuous to other modules; check continuity between VTD data pin and main data splice/module
- Bus idle/bias voltage and waveform (verify against factory specification or compare to a known-good vehicle)
- Check for short to battery or short to ground on the Class 2 data wire
- Verify stable supply voltage and ground at the VTD module connector
Diagnostic algorithm
- Retrieve DTCs and freeze frame with a scan tool. Record other U-codes and modules that report missing communication.
- Visually inspect the VTD module connector and harness for damage, corrosion, loose pins, or water intrusion. Repair any obvious issues.
- With ignition on, measure supply voltage and ground at the VTD module connector. Repair poor power/ground connections as required.
- Backprobe or access the Class 2 data pin at the VTD connector. Check for continuity to other known points on the Class 2 network; isolate harness if intermittent.
- Check for short to battery or ground on the data line (with ignition off) using an ohmmeter; disconnect modules to isolate the short if present.
- Use a lab scope or serial data monitor to view the data waveform while other modules are communicating. Compare waveform to known-good signals or factory spec.
- If wiring and connectors are good, swap or reprogram the VTD module per manufacturer procedure (only if replacement module is confirmed compatible).
- Clear codes, perform a key cycle and test drive to confirm the code does not return. Re-scan all modules to ensure full network restoration.
Likely causes
- Damaged or loose connector at the VTD module
- Broken or shorted Class 2 data wire between VTD and main bus
- Failed VTD module (less likely than wiring)
- Intermittent ground at module or chassis ground point
Fault status
Status
Loss of communication with VTD on Class 2 serial data network. Module messages not received by the network.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
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Code
U1192
Other
U — Network/User
SCP (J1850) Invalid or Missing Data for Primary Id
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring on the Class 2 serial data circuit to the VTD module
- Poor or missing ground at the VTD or related modules
- Corroded, loose, or damaged connector(s) at the VTD module or splice
- Failed VTD module
- Bus contention from another device (shorted data line)
- Aftermarket equipment tapped into the Class 2 bus causing interference
Symptoms
- Stored U1192 and possibly other network/communication U-codes
- Loss or intermittent operation of functions that rely on the VTD module
- Security/indicator lamp illumination or unexpected status messages
- Modules listed as 'not responding' or 'missing' on a scan tool
What to check
- Connect a factory-level scan tool; read U1192 and any other network or module communication codes and freeze frame data
- Note which modules are reporting on the Class 2 bus and which are missing
- Visually inspect wiring, connectors and splices to the VTD module for corrosion, bent pins, separations or water intrusion
- Check battery and charging system voltage (stable nominal voltage) while scanning
- Check module and chassis ground points associated with the VTD and Class 2 network
- Disconnect aftermarket accessories that may be tied into vehicle data or power circuits
Signal parameters
- Class 2 serial data line should be continuous to other modules; check continuity between VTD data pin and main data splice/module
- Bus idle/bias voltage and waveform (verify against factory specification or compare to a known-good vehicle)
- Check for short to battery or short to ground on the Class 2 data wire
- Verify stable supply voltage and ground at the VTD module connector
Diagnostic algorithm
- Retrieve DTCs and freeze frame with a scan tool. Record other U-codes and modules that report missing communication.
- Visually inspect the VTD module connector and harness for damage, corrosion, loose pins, or water intrusion. Repair any obvious issues.
- With ignition on, measure supply voltage and ground at the VTD module connector. Repair poor power/ground connections as required.
- Backprobe or access the Class 2 data pin at the VTD connector. Check for continuity to other known points on the Class 2 network; isolate harness if intermittent.
- Check for short to battery or ground on the data line (with ignition off) using an ohmmeter; disconnect modules to isolate the short if present.
- Use a lab scope or serial data monitor to view the data waveform while other modules are communicating. Compare waveform to known-good signals or factory spec.
- If wiring and connectors are good, swap or reprogram the VTD module per manufacturer procedure (only if replacement module is confirmed compatible).
- Clear codes, perform a key cycle and test drive to confirm the code does not return. Re-scan all modules to ensure full network restoration.
Likely causes
- Damaged or loose connector at the VTD module
- Broken or shorted Class 2 data wire between VTD and main bus
- Failed VTD module (less likely than wiring)
- Intermittent ground at module or chassis ground point
Fault status
Status
Loss of communication with VTD on Class 2 serial data network. Module messages not received by the network.
Repair difficulty: Medium
Diagnostic time: 0.5-2.5 hours
Similar codes
Repair manuals
Brands with available manuals
9,688
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