P0615

P0615 indicates the PCM has detected a fault in the starter relay control circuit, which on modern vehicles is the PCM-driven relay that energizes the starter solenoid only after immobilizer, brake pedal, clutch, or shifter inputs are satisfied. Cheapest-first diagnosis: locate the starter relay (usually in the underhood fuse/relay center or integrated into a TIPM/BCM) and verify it clicks when you attempt to start. Measure the relay control circuit at the PCM side with a DMM in min/max mode during a crank attempt — you should see B+ at rest and a pull-down to under 1V when the PCM commands the relay on. If the PCM is pulling the circuit low but the relay is not energizing, the relay or its B+ feed is at fault. If the PCM is not pulling the circuit low at all despite proper start-enable inputs, suspect an internal PCM driver failure or a missing input (clutch switch, brake switch, park/neutral signal). Inspect the relay socket for melted terminals — a chronically high-current starter draw burns relay contacts and pin sockets. The expensive misdiagnosis is replacing the starter motor because the engine won't crank, when the actual fault is a $25 relay or a $400 TIPM that is not energizing the solenoid in the first place.

Vehicle-specific patterns: 2007-2017 Chrysler/Dodge/Jeep with the TIPM (Town & Country, Grand Caravan, Wrangler JK, Grand Cherokee WK2, Ram 1500) are the textbook P0615 case — the internal starter relay solder joints in the TIPM fail, causing intermittent no-cranks and P0615, addressed by TIPM replacement or by repair-kit relay bypass per FCA TSB 08-001-15 and multiple class-action remedies. 2003-2007 GM trucks set P0615 from corroded starter-relay sockets in the underhood fuse block, often fixed by reterminating the socket. 2005-2010 Ford F-150, Expedition, and Mustang throw P0615 when the integrated starter relay in the BJB (battery junction box) develops high-resistance contacts. 2006-2012 Hyundai/Kia vehicles set P0615 from a failed PCM ground at G02 near the battery. Estimated repair: $30 to $1,400.