P1279 on 2020-2021 Jeep Cherokee: Starter Control Circuit 2 Open Causes and Fixes

What's Unique About the 2020-2021 Jeep CHEROKEE

For the 2020-2021 Jeep Cherokee (KL generation), this code is specifically linked to a known issue addressed by Jeep. A Technical Service Bulletin (TSB #9004352) and the associated STAR Case S2108000002 point to a particular brand of Run/Start relay ('Song Chuan') that is prone to failing in cold temperatures (typically below 15°F), causing 🎬 Watch: Real-world symptoms of the cold-weather relay failure. the exact symptoms of a no-start or a start-and-stall. This makes the diagnosis more direct than on other vehicles, where the cause might be a wider range of wiring or component failures.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Engine fails to crank or start
• Engine starts and immediately stalls (within 5 seconds)
• No sound or just a single click when trying to start
• Symptoms are worse or only occur in cold temperatures, often below 15°F (-9°C).
• Vehicle starts normally once the engine bay or ambient temperature warms up.
• Multiple, seemingly random error messages may appear on the dash after a failed start attempt, such as 'Service Parking Brake' or 'SDW Unavailable'.
• Check Engine Light (Malfunction Indicator Lamp) is illuminated.

Most Likely Causes

1. Defective Run/Start Relay 🔴 High Probability A specific relay manufacturer ('Song Chuan') used in these model years is known to fail in cold weather, as documented in TSB #9004352 and STAR Case S2108000002. The internal components of the relay contract in the cold, preventing proper electrical contact.
   How to confirm: Inspect the Run/Start relay in the under-hood Power Distribution Center (fuse box). Check if it is the 'Song Chuan' brand. You can also swap it with an identical relay from a non-critical circuit (like the horn) to see if the vehicle starts. The issue is most prevalent on vehicles built after September 2019.
   Typical fix: Replace the original Song Chuan relay with the updated Denso part specified by Jeep. This is a very common and well-documented fix in owner forums.
   Est. part cost: $15-$45
2. Corroded or Loose Wiring/Connections 🟡 Medium Probability All vehicles are susceptible to corrosion, especially at ground points or connectors exposed to the elements. Poor grounds can cause a wide array of electrical issues, including starting problems. Some Jeep models are noted for having main relay boxes in locations prone to corrosion.
   How to confirm: Visually inspect the wiring and connectors at the starter motor, the Power Distribution Center (PDC), battery terminals, and main chassis/engine block ground points for any signs of corrosion, damage, or looseness. Use a multimeter to check for continuity and voltage drops along the starter control circuit.
   Typical fix: Clean corroded terminals with a wire brush, repair or replace damaged wires, and ensure all connections are clean, bright, and tight.
   Est. part cost: $5-$50
3. Failed Starter Motor or Solenoid ⚪ Low Probability
   How to confirm: If the relay and wiring are good, test the starter solenoid for a 'click' when the key is turned. Perform a voltage drop test on the starter circuit or bench test the starter motor itself. A test light connected to battery power should light up when touching the starter solenoid's control terminal wire, indicating a good ground path through the solenoid windings; if it doesn't light, an open circuit exists in the starter.
   Typical fix: Replace the entire starter motor assembly, as the solenoid is typically integrated.
   Est. part cost: $200-$450

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): This is extremely rare and should only be considered after all other possibilities have been exhaustively ruled out. A diagnostic video exploring a no-crank condition on a 2020 Cherokee highlighted that even with starter circuit codes, the root cause could be a non-communicating PCM, which is a much deeper electrical issue.

Diagnosis Steps

1. Check for Technical Service Bulletins (TSBs). For this vehicle and code, TSB #9004352 is the primary starting point.
2. Locate the Power Distribution Center (PDC) under the hood on the driver's side.
3. Identify the Run/Start relay (often labeled K1 or K3, check your owner's manual or diagram). Inspect the relay to see if it is the 'Song Chuan' brand mentioned in the TSB.
4. If it is the suspect relay, replace it with the recommended Denso part. The primary replacement is 68406797AA, which is superseded by 68244159AA.
5. If the relay is not the issue, inspect the starter fuse (e.g., F19, 40A) and other related fuses.
6. Inspect all wiring and connections between the PDC and the starter motor for corrosion, damage, or loose fittings. Pay special attention to the main ground connections to the engine block and chassis.
7. If wiring and relays are good, test the starter motor and solenoid for proper function using a multimeter. Check for at least 9.6V at the starter solenoid's 'S' terminal during cranking.
8. If all components in the circuit test good, the issue may lie with the Powertrain Control Module (PCM), which requires advanced diagnostics.

Parts You'll Likely Need

• Run/Start Relay (OEM #68244159AA (replaces 68406797AA)) — This is the most common failure point for this specific code and symptom on 2020-2021 Cherokees, as identified in TSB #9004352. The original part is a faulty 'Song Chuan' relay.
  Trusted brands: Denso, Mopar
  OEM price range: $25-$45
  Aftermarket price range: $15-$30
• Starter Motor — If the relay and wiring are confirmed to be good, the starter motor assembly is the next most likely component to have failed.
  Trusted brands: Mopar, Bosch, Denso
  OEM price range: $350-$500
  Aftermarket price range: $200-$450

Technical Service Bulletins (TSBs) & Recalls

• 9004352 / NHTSA #10220495: Addresses a no-start or start-and-stall condition in cold temperatures, accompanied by DTC P1279, caused by a faulty 'Song Chuan' Run/Start relay. Advises replacement with Denso part 68406797AA or 68244159AA.
• S2108000002: The internal STAR Case that provides the diagnostic basis for TSB 9004352. It instructs technicians to inspect for a 'Song Chuan' relay on vehicles built after September 2019 and replace it with the Denso part if found.

Platform-Specific Known Issues

• TSB #9004352 directly links P1279 with a no-start or start-and-stall condition in cold weather on 2020-2021 KL Cherokee models. The bulletin identifies a specific brand of relay ('Song Chuan') as the culprit and advises replacement with an updated Denso part.
• The TSB also provides a backup part number (68244159AA) in case the primary replacement (68406797AA) is on backorder, and cautions that this specific relay should only be used in the Run/Start location due to its duty cycle rating.

Mechanic-Grade Diagnostic Values

• Starter Relay Coil Resistance — expected: 75 ± 5 ohms. Failure: A reading significantly outside this range indicates a faulty relay coil.
• Starter Relay Contacts (De-energized) — expected: No continuity (1 MΩ or higher). Failure: Continuity between terminals 30 and 87 when the relay is not powered indicates it is stuck closed.
• Starter Relay Contacts (Energized) — expected: Continuity (1 Ω or less). Failure: No continuity between terminals 30 and 87 when 12V is applied to the coil (terminals 85 and 86) indicates the relay is not closing the circuit.
• Starter Solenoid Control Wire Voltage (during crank) — expected: 9.6V or higher. Failure: Voltage below 9.6V during a crank attempt points to excessive resistance in the control circuit or a weak battery, not necessarily a bad starter.

Scan Tool Commands That Help

• wiTECH 2.0: OBDII Monitors / Engine Stop/Start Status — While not a direct test for P1279, this function allows a technician to view all system enablers for a start event, which can help identify if a module other than the PCM is preventing the start command.
• wiTECH 2.0: View DTCs / Clear All DTCs — Used to read the initial fault and to clear the code after a repair. The system will immediately rescan, and if P1279 reappears, it indicates the fault is still present.
• wiTECH 2.0: Topology View / Network Test — If a module is suspected of being offline (e.g., PCM, BCM), the topology view shows which modules are not communicating. A network test can then be run to check for communication line faults, which could be an underlying cause if the starter circuit itself tests good.

Wiring & Ground Locations

• Run/Start Relay (K1 or K3) — In the main Power Distribution Center (PDC) / fuse box, located under the hood on the driver's side.. This is the primary component identified by the TSB as the cause of P1279. Its failure in cold weather opens the starter control circuit.
• Starter Fuse (F19) — In the main Power Distribution Center (PDC), a 40A J-Case fuse.. This fuse protects the main power feed to the starter relay's load side. If this fuse is blown, the relay cannot send power to the starter solenoid.
• Engine Block Ground — Typically a large gauge wire from the battery negative terminal to a stud on the engine block, often near the starter or main accessory bracket.. A poor engine ground can cause high resistance in the starter circuit, leading to slow cranking or no-crank conditions that could be misdiagnosed as a component failure.
• Chassis Ground (G101) — A primary ground point from the battery negative terminal to the inner fender or chassis, near the battery.. This is the main ground for the vehicle's electrical system. Corrosion or looseness here can cause widespread issues, including problems with control modules that command the starter relay.

OEM Part Supersession History

• 68406797AA → 68244159AA — The original part number was the primary replacement specified in early versions of the TSB. The superseding part number became the validated alternate and is now the primary service part.
  Heads up: STAR Case S2108000002 specifically warns that part 68244159AA should ONLY be used in the Run/Start relay location, as using it in other locations that require higher duty cycles will lead to premature failure.

Model Year Variations Within This Range

• 2020-2021: According to STAR Case S2108000002, the problematic 'Song Chuan' relay was used on vehicles built after September 2019. Vehicles built before this date are less likely to experience this specific relay failure.