P2DAB: DC/AC Converter Control Module A Switch B Circuit Range/Performance

What it means

The DC/AC converter control module A detects that switch B is not operating within its expected range or performance limits.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

DC/AC converter control module A evaluates how switch B responds and whether its signal stays within the expected operating range. P2DAB sets when switch B’s response or signal performance falls outside those limits, even if the circuit is not simply open or shorted.

Common causes

Most likely first.

1. Switch aged - response slowed
2. High-resistance contact
3. Sensor element aged beyond calibration window

Symptoms

• Check-engine or hybrid-system warning light
• Reduced or unavailable DC/AC converter function

How to diagnose it

1. Record freeze-frame data and check live switch B signal and converter status in module A to identify when the response went out of range.
2. Inspect switch B circuit connectors and terminals for corrosion, looseness, or contamination that could add resistance or slow the signal.
3. Check the switch B wiring for damage and measure circuit resistance or voltage during the manufacturer’s specified test, comparing results with its specification.
4. If supported by the scan tool, compare switch B’s commanded and reported states during an approved functional test.
5. If wiring and connections are sound but the response remains slow or out of range, test switch B and converter control module A according to the manufacturer’s procedure.

Common fixes

• Clean or repair high-resistance or loose terminals in the switch B circuit.
• Repair wiring damage that causes excessive resistance or a distorted signal.
• Replace switch B if its response remains outside the expected range with a sound circuit.
• Reprogram or replace converter control module A if manufacturer testing identifies a software or internal module fault.

Can I keep driving?

Avoid relying on the DC/AC converter while its operation is reduced or unavailable, and heed any hybrid-system warning or limp-mode behavior. Converter performance may become less reliable if switch B’s response continues to drift.