Diagnosing Inoperative Gauges, Communication Concerns Setting DTCs

Some 2017-2018 Silverado, Sierra; 2017-2020 Tahoe, Suburban, Yukon, Escalade; 2019 Silverado LD, Silverado 2500/3500, Sierra Limited, Sierra 2500/3500; and 2019-2020 Silverado 4500HD/5500HD/6500HD models may have several communication concerns resulting in inoperative instrument panel cluster (IPC) gauges as well as a number of other performance conditions. There may be two possible causes for these conditions.

There may be an issue with the Serial Data Gateway Module if there are inoperative gauges along with ALL of the following conditions:

  • The PRNDL does not indicate the transmission position
  • Multiple service messages on the Driver Information Center and multiple MILs illuminated
  • The radio does not display the temperature and does not turn off when a door is opened
  • No audible feedback or IPC indicator when the turn signals are operating
  • DTC U0155 (Lost Communication with Instrument Cluster) is set in multiple control modules


If these conditions are found, the SDGM may be retaining power but not communicating on all CAN channels. Reset the module by removing the power feed fuse for the SDGM – F26DL for trucks (Fig. 19) and F28DL for SUV – and waiting one minute before reinstalling the fuse. Verify if the conditions have been corrected.


Fig. 19


The module reset solution may be a temporary fix. A software update correction for the affected model years is expected to be released later this year. Do no replace any parts for these conditions.

Another possible cause may be the SDGM connector terminals if there are inoperative gauges along with ANY of the following conditions:

  • A no start or start/stall condition
  • An illuminated SIR MIL or Service Airbag message
  • A Service Suspension message
  • Blank radio display
  • The steering wheel controls are not illuminated
  • No audible feedback when the turn signals are operating
  • Inoperative HVAC controls
  • Any of the following DTCs are set – B1011, B1370, B3980, U0020, U0029, U007D, U0073, U0078, U0100, U0101, U0102, U0104, U0121, U0140, U0146, U0151, U0155, U0164, U0184, U0186, U0198, U0237, U0255, U0422


These conditions may be the result of bent, backed out, or loose terminals on the SDGM X1 or X2 connector terminals.

If removing the power feed fuse for the SDGM does not correct the conditions, inspect the SDGM connector for any loose, bent, or damaged terminals. (Fig. 20) Replace the affected terminal as required. If there is damage to the connector body, replace the connector housing as outlined in the Service Information Connector End View document.


Fig. 20


For more information, refer to #PIT5586E.


– Thanks to Troy Henige

Tapping Sound from Engine
DTCs Set in the TCM

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