Home ยป Fix Released For Cadillac CT6 PHEV Transmission Wiring Harness Issue

Fix Released For Cadillac CT6 PHEV Transmission Wiring Harness Issue

Fix Released For Cadillac CT6 PHEV Transmission Wiring Harness Issue

Cadillac’s parent company, General Motors, has released a service update to address an issue with the transmission wiring harness in certain units of 2017 and 2018 model year Cadillac CT6 PHEV (plug-in hybrid vehicle).

The problem: affected vehicles may have a faulty thermistor crimp in the transmission wiring harness. 

The hazards: potential problems caused by the transmission wiring harness thermistor crimp have not been specified. A thermistor is a type of resistor that varies resistance based on ambient temperatures, often used to measure temperatures in automobiles.

The fix: dealerships will replace the entire transmission wiring harness. The repair will be performed at no cost to the vehicle owner. 

Affected components:

  • Transmission wiring harness
  • Transmission thermistor crimp
  • Four-mode hybrid transmission

Affected vehicles: 

  • 2017 Cadillac CT6 PHEV
  • 2018 Cadillac CT6 PHEV

Number of affected vehicles: a total of 551 units of the CT6 PHEV have been affected by this service update.

Next steps: owners of affected vehicles will be contacted with instructions to make an appointment at their dealer. Additionally, owners may reach out to Cadillac directly to address any questions they may have using the information included below. 

Please note that this service update only applies to units of the  CT6 that PHEV, meaning they feature plug-in hybrid-electric propulsion. Models with a traditional (non-hybrid) gasoline combustion engine are not affected by the transmission wiring harness issue addressed in this service update.


  • Service update number: N202318000
  • Cadillac customer service: 1-800-333-4223

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Written by
Alexandra is a Colorado-based journalist with a passion for all things involving horsepower, be it automotive or equestrian.

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