Invalid Or Missing Data For Transfer Case Shift Control Module
Table of contents
U1026 CADILLAC Possible Causes
- Faulty Transfer Case Shift Control Module (TCSCM)
- Transfer Case Shift Control Module harness is open or shorted
- Transfer Case Shift Control Module circuit poor electrical connection
How do I fix code U1026 CADILLAC?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Tech Notes
- This is typically an electrical wiring connection issue at one of the controllers being monitored by the manufacturer.
- It can occur if:
- Someone changes a battery while the ignition switch is left on, that is, left in the “Run” position.
- Someone flashes/upgrades their engine controller – other modules unable to communicate with PCM during this process – this will set U1026 at a multitude of controllers on the vehicle – all false codes. Erase and carry on.
- May need to disconnect both battery cables and touch them together for 15 seconds. Reattach battery cables, positive first, then negative and see if a soft reset helps.
Cost of diagnosing the U1026 CADILLAC code
The cost of diagnosing the U1026 CADILLAC code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Service 4WD Light ON
- Engine cranks but may not start – may be intermittent
- May / may not shift from 2-wheel drive to 4-wheel drive / 4-wheel drive to 2-wheel drive
- May or may not be able to communicate with a scan tool / depends on problem
U1026 CADILLAC 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 the 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 module 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 Diagnostic Trouble Code (DTC) U1026 is set.