What does it mean?
OBD II fault code B1352 is a manufacturer specific code that is defined by carmakers Ford and Jaguar as “Ignition key-in – circuit failure”, and is set when the PCM (Powertrain Control Module) detects a malfunction or general failure in circuits that are active when the ignition is switched off, but while the key is still in the ignition. Note that the most commonly affected circuits are those that feed power to the door chimes through the ignition switch.
While having door chimes that alert a driver that the key is still in the ignition while the doors (or any single door) are/is open is a good idea in principle, the actual chimes and their control circuits are notoriously unreliable and prone to failure, and especially so on Ford applications. In terms of operation, the door chime circuit is activated when a door is opened, but the key in the ignition also control circuits that prevent the chime going off while the ignition is switched “ON”.
Thus, when the ignition is switched “OFF”, the key completes a circuit via the “door open” switch in the doorjamb, which activates the door chime until the key is removed from the ignition switch. While many drivers regard the door chimes as a major nuisance, their purpose is both to prevent drivers locking the vehicle with the key in the ignition, as well as to serve as a warning that one or more doors are not fully closed and latched while driving above a predefined speed.
However, failures in door chime circuits often cause short circuits that can, and do, drain batteries, which can cause no-start conditions and in cases where the battery drain is severe, the total or partial loss of vital programming in one or more control modules, including the PCM.
Symptoms
- The warning chime sounds continuously, or never sounds when the key is left in the lock
- Interior and courtesy lamps stay on and drain the battery overnight
- Key-in-ignition warning message displayed incorrectly
- The doors may lock with the key still inside, because the interlock does not see the key
- Delayed accessory functions such as windows and lamps behave incorrectly
Likely causes
- Faulty key-in-ignition switch inside the ignition lock cylinder housing
- Worn or contaminated contacts in the ignition switch assembly
- Short to ground on the key-in circuit, a frequent cause of overnight battery drain
- Broken or chafed wire between the ignition switch and the body control module
- Corroded connector at the base of the steering column
- Door ajar switch fault interacting with the chime logic, since both inputs are combined
- Body control module input stage failure
How to fix it
- Watch the key-in-ignition input in live data while inserting and removing the key
- Unplug the ignition switch connector and check whether the circuit is shorted to ground
- Inspect the column connector for corrosion, water tracking and pushed-back pins
- Test the door ajar switches as well, because the chime logic combines both inputs
- Perform a parasitic draw test if the vehicle is losing battery charge overnight
- Replace the key-in-ignition switch or the ignition switch assembly when its contacts do not change state
- Repair the harness section, clear codes and confirm the chime, lamps and locking all behave correctly