P2AF3 Starter Relay C Control Circuit Low

P2AF3 sets when the control line of starter relay C is pulled toward ground at a moment the module expects a different level. What that does to the relay depends on the driver type: with ground-side switching the short acts like a permanent on command, with supply-side switching the coil never gets current. No manufacturer publishes a set condition for P2AF3. Stellantis uses relay C as Starter Relay 3, the battery isolation relay of its stop-start Jeep and RAM models, where an energised coil splits the two batteries; only the stuck codes of that relay appear in its bulletins. GM's comparable short-to-ground test on the tandem starter pinion relay (P26E5) looks for 0.5 Ω or less to ground with 8 failures in 10 samples, Type B. Open and short-to-voltage faults are P2AF2 and P2AF4.

Likely causes

Symptoms

• Stop-start inoperative
• Relay energised all the time or not at all, depending on circuit design
• Possible no-crank

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov.