Pinpoint Test M: One Turn Signal Lamp Is Inoperative/Always On
Turn Signal and Hazard Lamps
Pinpoint Tests
Pinpoint Test M: One Turn Signal Lamp Is Inoperative/Always On
Refer to Wiring Diagram Set 90, Turn Signal/Stop/Hazard Lamps for schematic and connector information. Diagrams By Number
Normal Operation
The Steering Column Control Module (SCCM) monitors multifunction switch input. The SCCM sends a message to the Body Control Module (BCM) over the High Speed Controller Area Network (HS-CAN), indicating the multifunction switch is in the OFF, LH or RH TURN position. When the BCM receives a message indicating a LH or RH turn request, the BCM provides on/off voltage to the appropriate turn lamps.
The front and auxiliary (exterior mirror) turn lamps share the same fuses as the rear stoplamps. The rear turn lamps are controlled utilizing the rear stoplamp circuitry.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Bulb socket
- Auxiliary turn signal lamp
- Exterior mirror
- BCM
PINPOINT TEST M: ONE TURN SIGNAL LAMP IS INOPERATIVE/ALWAYS ON
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
-------------------------------------------------
M1 CHECK THE STOPLAMPS
- Apply and release the brake pedal while observing the stoplamps.
- Do the stoplamps operate correctly?
Yes
GO to M2.
No
GO to Pinpoint Test J Pinpoint Test J: One Or More Stoplamps Are Inoperative.
-------------------------------------------------
M2 DETERMINE IF A TURN LAMP IS ALWAYS ON
- Ignition ON.
- Observe the front turn lamps and the signal mirror lamps if equipped.
- Is any turn lamp always on?
Yes
GO to M3.
No
GO to M4.
-------------------------------------------------
M3 CHECK THE TURN LAMP OUTPUT CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: BCM C2280F.
- Ignition ON.
- Does the turn lamp in question continue to illuminate?
Yes
For the LH front turn lamp, REPAIR circuit CLS21 (BU/GN) for a short to voltage. TEST the system for normal operation. For the RH front turn lamp, REPAIR circuit CLS25 (YE/VT) for a short to voltage. TEST the system for normal operation.
No
GO to M15.
-------------------------------------------------
M4 CHECK FOR AUXILIARY TURN SIGNALS IN THE OUTSIDE REAR VIEW MIRRORS
- Determine if the vehicle is equipped with turn signals in the outside rear view mirrors.
- Is the vehicle equipped with turn signals in the outside rear view mirrors?
Yes
GO to M7.
No
GO to M5.
-------------------------------------------------
M5 CHECK FOR VOLTAGE TO THE BULB SOCKET
- Ignition OFF.
- Disconnect: Inoperative Front Turn Lamp.
- Activate the hazard flasher lamp function.
- Measure the voltage between the LH front turn lamp C1023-3, circuit CLS21 (BU/GN), harness side and ground; or between the RH front turn lamp C1043-3, circuit CLS25 (YE/VT), harness side and ground.
- Does the voltage alternate between 0 and greater than 10 volts?
Yes
GO to M6.
No
GO to M12.
-------------------------------------------------
M6 CHECK THE BULB SOCKET GROUND CIRCUIT FOR AN OPEN
- Measure the voltage between the LH front turn lamp C1023-3, circuit CLS21 (BU/GN), harness side and the LH front turn lamp C1023-1, circuit GD123 (BK/GY), harness side; or between the RH front turn lamp C1043-3, circuit CLS25 (YE/VT), harness side and the RH front turn lamp C1043-1, circuit GD120 (BK/GN), harness side.
- Does the voltage alternate between 0 and greater than 10 volts?
Yes
INSTALL a new bulb socket. TEST the system for normal operation.
No
REPAIR circuit GD123 (BK/GY) (LH front turn lamp) or circuit GD120 (BK/GN) (RH front turn lamp) for an open. TEST the system for normal operation.
-------------------------------------------------
M7 DETERMINE IF THE FRONT AND AUXILIARY TURN SIGNAL ARE BOTH INOPERATIVE
- Activate the hazard lamp function on and observe the auxiliary turn signal and the corresponding front turn lamp.
- Are the auxiliary turn signal and the corresponding front turn lamp both inoperative?
Yes
GO to M11.
No
GO to M8.
-------------------------------------------------
M8 CHECK FOR VOLTAGE TO THE EXTERIOR MIRROR OR THE BULB SOCKET
- Ignition OFF.
- Disconnect: Inoperative Front Turn Lamp or Exterior Mirror.
- Activate the hazard flasher lamp function.
- For a front lamp, measure the voltage between the LH front turn lamp C1023-3, circuit CLS21 (BU/GN), harness side and ground; or between the RH front turn lamp C1043-3, circuit CLS25 (YE/VT), harness side and ground.
- For an auxiliary turn signal, measure the voltage between the LH exterior mirror C521-10, circuit CLS21 (BU/GN), harness side and ground; or between the RH exterior mirror C615-10, circuit CLS25 (YE/VT), harness side and ground.
- Does the voltage alternate between 0 and greater than 10 volts?
Yes
GO to M9.
No
REPAIR circuit CLS21 (BU/GN) (LH turn) or circuit CLS25 (YE/VT) (RH turn) for an open. TEST the system for normal operation.
-------------------------------------------------
M9 CHECK THE EXTERIOR MIRROR OR THE BULB SOCKET GROUND CIRCUIT FOR AN OPEN
- For a front lamp, measure the voltage between the LH front turn lamp C1023-3, circuit CLS21 (BU/GN), harness side and the LH front turn lamp C1023-1, circuit GD123 (BK/GY), harness side; or between the RH front turn lamp C1043-3, circuit CLS25 (YE/VT), harness side and the RH front turn lamp C1043-1, circuit GD120 (BK/GN), harness side.
- For an auxiliary turn signal, measure the voltage between the LH exterior mirror C521-10, circuit CLS21 (BU/GN), harness side and the LH exterior mirror C521-8, circuit GD134 (BK/VT), harness side; or between the RH exterior mirror C615-10, circuit CLS25 (YE/VT), harness side and the RH exterior mirror C615-8, circuit GD139 (BK/YE), harness side.
- Does the voltage alternate between 0 and greater than 10 volts?
Yes
For a front turn lamp, INSTALL a new bulb socket. TEST the system for normal operation. For an auxiliary turn signal, GO to M10.
No
REPAIR circuit GD123 (BK/GY) (LH front turn lamp), circuit GD120 (BK/GN) (RH front turn lamp), circuit GD134 (BK/VT) (LH auxiliary turn signal) or circuit GD139 (BK/YE) (RH auxiliary turn signal) for an open. TEST the system for normal operation.
-------------------------------------------------
M10 CHECK THE CIRCUITS TO THE LED ASSEMBLY FOR AN OPEN
- Turn the hazard function off.
- Disconnect: Suspect LED Turn Lamp.
- Measure the resistance between the suspect exterior mirror pin 10, component side and the LED turn lamp connector pin 1 (GN/WH), harness side; and between the suspect exterior mirror pin 8, component side and the LED turn lamp connector pin 2 (BK), harness side.
- Are the resistances less than 5 ohms?
Yes
INSTALL a new auxiliary turn signal lamp. REFER to Side Lamp Assembly - Outside Rear View Mirror Side Lamp Assembly - Outside Rear View Mirror. TEST the system for normal operation.
No
INSTALL a new exterior mirror. REFER to Rear View Mirrors Exterior Mirror. TEST the system for normal operation.
-------------------------------------------------
M11 ISOLATE THE EXTERIOR MIRROR
- Ignition OFF.
- Disconnect: Suspect Exterior Mirror.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: BCM Self-Test.
- Clear the DTCs and repeat the self-test (required to enable the turn lamp output driver if DTC U1000:00 is present).
- Activate the hazard flasher lamp function.
- Does the inoperative front turn lamp now flash on and off?
Yes
INSTALL a new exterior mirror in question. REFER to Rear View Mirrors Exterior Mirror. TEST the system for normal operation.
No
GO to M12.
-------------------------------------------------
M12 ISOLATE THE BULB SOCKET
- Turn the hazard lamp function off.
- Ignition OFF.
- Disconnect: Inoperative Front Turn Lamp.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: BCM Self-Test.
- Clear the DTCs and repeat the BCM on-demand self-test (required to enable the turn lamp output driver if DTC U1000:00 is present).
- Turn the hazard lamp function on.
- Measure the voltage between the LH front turn lamp C1023-3, circuit CLS21 (BU/GN), harness side and ground; or between the RH front turn lamp C1043-3, circuit CLS25 (YE/VT), harness side and ground.
- Does the voltage alternate between 0 and greater than 10 volts?
Yes
INSTALL a new bulb socket. TEST the system for normal operation.
No
GO to M13.
-------------------------------------------------
M13 CHECK THE TURN LAMP OUTPUT CIRCUIT FOR A SHORT TO GROUND
- Turn the hazard lamp function off.
- Ignition OFF.
- Disconnect: BCM C2280F.
- Measure the resistance between the LH front turn lamp C1023-3, circuit CLS21 (BU/GN), harness side and ground; or between the RH front turn lamp C1043-3, circuit CLS25 (YE/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to M14.
No
REPAIR the circuit in question for a short to ground. After the repair: If no DTCs are present, TEST the system for normal operation. If DTC U1000:00 is present, CLEAR the DTCs and REPEAT the self-test (required to enable the turn lamp output driver if DTC U1000:00 is present). TEST the system for normal operation. If DTC U3000:49 is present, INSTALL a new BCM. REFER to Multifunction Electronic Modules Service and Repair. TEST the system for normal operation.
-------------------------------------------------
M14 CHECK THE BCM TURN LAMP OUTPUT CIRCUIT FOR AN OPEN
- Measure the resistance between the inoperative front turn lamp, harness side and the BCM, harness side as follows:
- Is the resistance less than 5 ohms?
Yes
GO to M15.
No
REPAIR the circuit in question for an open. TEST the system for normal operation.
-------------------------------------------------
M15 CHECK FOR CORRECT BCM OPERATION
- Disconnect all the BCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM 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. REFER to Multifunction Electronic Modules Service and Repair. 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.
-------------------------------------------------