What it means
The motor supply voltage of the second auxiliary transmission fluid pump is below the operating range.
At a glance
- Usually lights the check-engine light
How it works
Electric or auxiliary transmission fluid pump B receives electrical power through its motor supply circuit to provide hydraulic pressure when required. P276B sets when the supply voltage at pump B falls below its operating range, which may prevent the pump from developing pressure.
Common causes
Most likely first.
- High-resistance battery feed
- Weak battery sags under pump current
- Connector pins corroded - high contact resistance
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
- Check freeze-frame data and live pump B supply voltage, especially when the pump is commanded on.
- Inspect the battery condition and charging system for a weak battery or unstable supply.
- Check pump B’s feed wiring and connector for corrosion, loose terminals, or other high-resistance connections.
- Measure voltage drop across the pump B supply and ground paths while the pump is commanded on.
- Compare the readings with the manufacturer's specification and inspect the relevant fuse and feed connections.
Common fixes
- Clean and tighten corroded or loose pump B supply connections.
- Repair high-resistance or damaged feed wiring to pump B.
- Replace a weak battery or repair a charging fault if testing confirms it is causing the voltage drop.
- Replace pump B if its feed voltage is correct but the motor still draws the circuit below range.
Can I keep driving?
Limit driving if shifts are slipping, delayed, or harsh, and avoid stop-start operation that depends on pump B. Low supply voltage can leave the transmission without auxiliary pressure when needed and may worsen shift problems.
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.