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OBD-II Diagnostic Trouble Code
B1603

Driver pretensioner squib short

B
Body
comfort / safety
1
Mfr
manufacturer code
6
Body subsystem
03
Driver pretensioner squib short
Severity · general guide
Varies
Body/safety — depends on system
Code type
Jeep
System
Body
Model
Grand Cherokee
Years
2011
Quick answer

On the 2011 Jeep Grand Cherokee WK2, B1603-11 is set by the HVAC A/C Heater Control when it detects a short to ground on the right sun sensor (solar sensor) signal circuit -- the G139 Sun Sensor Signal 2 circuit that feeds solar-load data from the passenger-side dashboard sensor to the automatic climate control module.

What B1603 means

The 2011 Grand Cherokee WK2 Automatic Temperature Control (ATC) system uses two solar sensors -- one for the left cabin side and one for the right -- to measure sunlight intensity through the windshield. The A/C Heater Control module monitors the voltage of both sensors continuously with the ignition on. The right sensor's signal travels on the G139 Sun Sensor Signal 2 circuit. When the A/C Heater Control detects that the resistance of the G139 circuit to chassis ground falls below approximately 100 kilohms, it stores B1603-11 -- indicating a short to ground on that circuit. Fault type byte (FTB) -11 in the Chrysler/Jeep numbering system designates 'circuit short to ground'. The result is that the ATC system loses real-time solar compensation for the passenger side of the cabin, causing it to respond less accurately to direct sunlight on that side. Note: B1603 is an HVAC module code, not a restraints code -- it does not relate to airbag squibs or seatbelt pretensioners on this platform.

Symptoms

  • HVAC warning indicator or fault message if the Uconnect system is equipped to display HVAC faults
  • Automatic temperature control behaves slightly differently on the passenger side in strong sunlight -- may overcool or undercool relative to a working system
  • B1603-11 stored under HVAC module DTCs (not powertrain codes -- requires an HVAC-capable scan tool to read)
  • No effect on engine performance, transmission, or airbag systems
  • No noticeable performance difference in mild or overcast conditions

Common causes

  • Short to ground on the G139 Sun Sensor Signal 2 circuit -- most often a pinched wiring harness near the top of the A-pillar or dashboard trim where the sensor cable routes
  • Failed right solar sensor with internal short -- the sensor element itself can fail and drag the signal line to ground
  • Corroded or damaged connector at the sun sensor pigtail near the top of the dashboard
  • Damaged A/C Heater Control module with an internal short pulling the G139 input to ground (rare)

Diagnostic approach

  1. Confirm the DTC is active with an HVAC-capable scan tool — Read HVAC DTCs with the ignition on, engine not running. If B1603-11 is active, the short is present right now. If stored-only, the fault is intermittent -- inspect the harness near the A-pillar for abrasion first.
  2. Check the G139 Sun Sensor Signal 2 circuit for a short to ground — Turn the ignition off. Disconnect both the A/C Heater Control C1 harness connector and the sun sensor harness connector. Measure resistance between chassis ground and the G139 circuit at the disconnected harness. If resistance is below 100 kilohms, the wiring between the two disconnected points has a short -- trace and repair the harness.
  3. Replace the right sun sensor if the wiring checks out clean — If resistance is above 100 kilohms with both connectors disconnected, reconnect the A/C Heater Control and disconnect only the sensor -- if the short returns, the sensor has an internal fault. Replace the right solar sensor and run the HVAC Verification Test to confirm the code does not reset.

Make & model notes

Jeep: On the WK2 Grand Cherokee, the solar sensors are located at the top of the windshield near the interior rear-view mirror base, separate from the rain/light sensor. The right sensor (G139 circuit) is a small disc-shaped photodiode embedded in the dash top pad. Replacement requires careful removal of the upper dash trim to avoid cracking the pad.

Jeep: B1603-11 only affects the automatic climate control system -- single-zone manual HVAC-equipped WK2s do not have solar sensors and will not set this code. Confirm your trim level has ATC before starting diagnosis; Laredo base models with manual HVAC are not equipped with solar sensors.

FAQ

Does B1603-11 affect Jeep Grand Cherokee air conditioning performance?

Not dramatically. The solar sensor provides a correction factor to the ATC system -- its loss causes the system to respond more slowly to sunlight changes, but cooling and heating still function normally. The cabin will be comfortable but automatic temperature regulation is less precise on the passenger side.

Is B1603-11 in a Jeep Grand Cherokee related to the airbag or pretensioner system?

No. In the 2011 Grand Cherokee WK2, B1603 is set by the HVAC A/C Heater Control module and relates to the right solar sensor. It is completely separate from the Occupant Restraint Controller (ORC). Airbag and pretensioner squib codes on this vehicle use the B1B00 through B1B2x and B1Cxx code ranges.

Can I clear B1603-11 on my Jeep without repairing the wiring?

You can clear it with a scan tool but it will return immediately if the short to ground on the G139 circuit is still present. The A/C Heater Control monitors the sensor every time the ignition is on.