P2AF9: Starter Relay D Control Circuit High

What it means

Starter relay D reports a control circuit high condition. Engine cranking can be inhibited or commanded unintentionally.

At a glance

• Usually lights the check-engine light

How it works

Starter relay D switches its part of the cranking circuit when commanded by the module. The module sets P2AF9 when relay D's control circuit is higher than expected, which can indicate a wire shorted to battery voltage, an open relay coil, or poor connector contact.

Common causes

Most likely first.

1. Control wire shorted to B+
2. Open relay coil
3. Connector pins corroded - high contact resistance

Symptoms

• Check-engine light may be on
• Engine may not crank
• Intermittent starting difficulty

How to diagnose it

1. Record freeze-frame and related starting-system codes, and note whether the high reading accompanies a failed or intermittent start.
2. Inspect relay D's harness for damaged insulation touching a power feed and check its connector for corrosion or loose pins.
3. Identify relay D from the vehicle's fuse-box diagram and inspect its seating and socket for damage.
4. Using the manufacturer's wiring diagram, test relay D's control wire for a short to battery voltage.
5. If the wire and connector are sound, test relay D's coil and control circuit using the manufacturer's procedure for an open coil.

Common fixes

• Clean or repair corroded relay D connector terminals.
• Repair relay D's control wire if it is shorted to a power feed.
• Replace relay D if its coil is open.

Can I keep driving?

The fault can cause a no-crank or intermittent start, so avoid trips where a failed restart could leave you stranded. If the vehicle starts and the starter disengages normally, a short drive is generally possible, but get the circuit diagnosed soon.