Pinpoint Test S: The Turn Signal Lamps Flash Fast And No Bulbs Are Inoperative
Turn Signal and Hazard Lamps
Pinpoint Test S: The Turn Signal Lamps Flash Fast And No Bulbs Are Inoperative (MKX)
Normal Operation
The Body Control Module (BCM) monitors the current draw of the front turn lamps. When the current draw is insufficient from the front turn lamp, such as using an LED lamp in place of an incandescent lamp, the BCM (Body Control Module) interprets this as an inoperative bulb and fast flashes (bulb outage mode) the turn lamps.
For the rear lamps, the Body Control Module (BCM) sends a voltage signal to each rear LED lamp through a feedback circuit. If the Body Control Module (BCM) detects a fault from the feedback circuit, the turn lamps flash fast for the side affected (LH or RH).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Rear lamp assembly
- BCM (Body Control Module)
PINPOINT TEST S : THE TURN SIGNAL LAMPS FLASH FAST AND NO BULBS ARE INOPERATIVE (MKX)
S1 CHECK THE FRONT TURN LAMP BULB
- Ignition OFF.
- Inspect the front turn lamp bulb and make sure it is the correct type (3457NAK).
Is the front turn lamp bulb the correct type?
Yes
GO to S2.
No
INSTALL a new front turn lamp bulb. TEST the system for normal operation.
S2 CHECK FOR A VOLTAGE SIGNAL TO THE REAR LAMP
- Disconnect: Suspect Rear Lamp.
- Ignition ON.
- Measure the voltage between the LH rear lamp C414-5, circuit CLS55 (GN/BU), harness side and ground; or between the RH rear lamp C417-5, circuit CLS54 (BU/OG), harness side and ground.
Is the voltage approximately 5 volts?
Yes
GO to S3.
No
GO to S4.
S3 CHECK THE REAR LAMP JUMPER HARNESS
- Ignition OFF.
- Inspect the rear lamp jumper harness for opens and shorts.
Is the rear lamp jumper harness OK?
Yes
INSTALL a new rear lamp assembly. REFER to Rear Lamp Assembly - Liftgate Rear Lamp Assembly - Liftgate. TEST the system for normal operation.
No
REPAIR or INSTALL a new rear lamp jumper harness. TEST the system for normal operation.
S4 CHECK THE OUTAGE CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: BCM (Body Control Module) C2280C.
- Ignition ON.
- Measure the voltage between the LH rear lamp C414-5, circuit CLS55 (GN/BU), harness side and ground; or between the RH rear lamp C417-5, circuit CLS54 (BU/OG), harness side and ground.
Is any voltage present?
Yes
REPAIR circuit CLS55 (GN/BU) (LH rear lamp) or circuit CLS54 (BU/OG) (RH rear lamp) for a short to voltage. TEST the system for normal operation.
No
GO to S5.
S5 CHECK THE OUTAGE CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the LH rear lamp C414-5, circuit CLS55 (GN/BU), harness side and ground; or between the RH rear lamp C417-5, circuit CLS54 (BU/OG), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to S6.
No
REPAIR circuit CLS55 (GN/BU) (LH rear lamp) or circuit CLS54 (BU/OG) (RH rear lamp) for a short to ground. TEST the system for normal operation.
S6 CHECK THE OUTAGE CIRCUIT FOR AN OPEN
- Measure the resistance between the LH rear lamp C414-5, circuit CLS55 (GN/BU), harness side and the BCM (Body Control Module) C2280C-16, circuit CLS55 (GN/BU), harness side; or between the RH rear lamp C417-5, circuit CLS54 (BU/OG), harness side and the BCM (Body Control Module) C2280C-3, circuit CLS54 (BU/OG), harness side.
Is the resistance less than 5 ohms?
Yes
GO to S7.
No
REPAIR circuit CLS55 (GN/BU) (LH rear lamp) or circuit CLS54 (BU/OG) (RH rear lamp) for an open. TEST the system for normal operation.
S7 CHECK FOR CORRECT BCM (Body Control Module) OPERATION
- Disconnect all the BCM (Body Control Module) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM (Body Control Module) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new BCM (Body Control Module). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.