P085B
Gear Shift Control Module B Communication Circuit Low
The gear shift control module B communication circuit reports a communication circuit low condition. Shift command exchange is impaired.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Common causes
Ordered by how often each turns out to be the cause.
- Bus wire shorted to groundCommon
- Module output lowPossible
- Gateway module routing CAN messages incorrectlyLess likely
Parts involved
- Gear Shift Control Module B
- Wiring Harness
P085B is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.