What it means
Shift timing solenoid B control circuit reads stuck low — short to ground.
At a glance
- Usually lights the check-engine light
How it works
Shift timing solenoid B is a transmission valve controlled through an electrical circuit by the TCM. This low-circuit code sets when the monitored control signal for solenoid B stays below the expected range, commonly because the control wire is shorted to ground or the coil is internally shorted.
Common causes
Most likely first.
- Short to ground in the solenoid control wiring
- Shift Timing Solenoid B coil shorted internally
- Damaged connector or corroded terminals
- Fault in the transmission control module driver
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
How to diagnose it
- Capture freeze-frame data and check transmission live data for the solenoid B command and circuit status when the low condition is detected.
- Inspect the solenoid B connector and harness for crushed insulation, corrosion, fluid intrusion, or a wire contacting ground.
- With power isolated as directed by the service procedure, test the solenoid B control wire for a short to ground.
- Measure solenoid B coil resistance and compare it with the manufacturer's specification to check for an internal short.
- If wiring and coil tests pass, verify the TCM driver operation using the manufacturer's diagnostic procedure.
Common fixes
- Repair the solenoid B control wire where it is shorted to ground.
- Clean or replace damaged, corroded connector terminals.
- Replace shift timing solenoid B if its coil is confirmed shorted.
- Repair the TCM driver only after the wiring and solenoid test correctly.
Can I keep driving?
Avoid towing, steep climbs, and hard acceleration, and arrange diagnosis promptly because solenoid B may not control shifts correctly. If the transmission slips, loses gears, or enters a restricted operating mode, stop driving to limit further damage.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.