Pinpoint Test M: The Stoplamps Are On Continuously
Stoplamps
Pinpoint Test M: The Stoplamps Are On Continuously
Normal Operation
When the brake pedal is applied, the stoplamp switch routes voltage to the Smart Junction Box (SJB), the high mounted stoplamp, the Trailer Brake Control (TBC) module (if equipped), the Remote Function Actuator (RFA) module and the PCM. When the SJB (Smart Junction Box) detects the brake pedal is applied, the SJB (Smart Junction Box) provides voltage to the LH and RH rear stoplamps.
On vehicles equipped with adaptive cruise control, voltage can also be supplied to all the previously mentioned components (except the PCM) by the adaptive cruise control relay (controlled by the ABS module). The ABS module controls the coil side of the adaptive cruise control stoplamp relay by providing ground to the relay coil. The ABS module activates this relay when the adaptive cruise control is active and the system is activating the brakes to slow the vehicle.
- DTC B1485 (Brake Pedal Input Short to Battery)- an on-demand DTC that sets when the SJB (Smart Junction Box) detects a short to voltage from the stoplamp switch input circuit.
- DTC C1105 (Traction Control Disable Lamp Circuit Short To Battery)- sets when the ABS module detects a short to ground from the adaptive cruise control stoplamp relay coil ground supply circuit during an ignition cycle from OFF to ON.
- DTC P1571:12 (Brake Switch: Circuit Short To Battery)- an on-demand DTC that sets when the RFA (Remote Function Actuator) detects a short to voltage from the stoplamp switch output circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Adaptive cruise control stoplamp relay
- Stoplamp switch
- ABS module
- RFA (Remote Function Actuator) module
- TBC (Trailer Brake Control) module
- SJB (Smart Junction Box)
- PCM
PINPOINT TEST M : THE STOPLAMPS ARE ON CONTINUOUSLY
M1 DETERMINE IF ALL THE STOPLAMPS ARE ILLUMINATED
- Ignition ON.
- Observe the stoplamps with the brake pedal released.
Are all of the stoplamps illuminated?
Yes
GO to M3.
No
GO to M2.
M2 CHECK THE STOPLAMPS VOLTAGE SUPPLY CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: SJB (Smart Junction Box) C2280D.
Do the stoplamps continue to illuminate?
Yes
REPAIR circuit CLS18 (GY/BN) (LH rear lamp) or circuit CLS19 (VT/OG) (RH rear lamp) for a short to voltage. TEST the system for normal operation.
No
GO to M13.
M3 CHECK THE STOPLAMP SWITCH
- Disconnect: Stoplamp Switch C278.
Do the stoplamps continue to illuminate?
Yes
GO to M4.
No
INSTALL a new stoplamp switch. REFER to Stoplamp Switch . CLEAR the DTCs. REPEAT the self-test.
M4 CHECK THE PCM
- Disconnect: PCM C175B (3.7L) or C1381B (3.5L GTDI).
Do the stoplamps continue to illuminate?
Yes
If equipped with adaptive cruise control, GO to M5.
If not equipped with adaptive cruise control, GO to M9
No
GO to M12.
M5 CHECK THE ADAPTIVE CRUISE CONTROL RELAY OUTPUT
- Disconnect: Adaptive Cruise Control Relay.
Do the stoplamps continue to illuminate?
Yes
GO to M9.
No
GO to M6.
M6 CHECK THE STOPLAMP SWITCH OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE (TO THE ADAPTIVE CRUISE CONTROL STOPLAMP RELAY)
- Measure the voltage between the adaptive cruise control stoplamp relay pin 4, circuit CCB08 (VT/WH), BJB (Battery Junction Box) face side and ground.
Is any voltage present?
Yes
REPAIR circuit CCB08 (VT/WH) for a short to voltage. TEST the system for normal operation.
No
GO to M7.
M7 CHECK THE ADAPTIVE CRUISE CONTROL STOPLAMP RELAY
- Substitute a known good relay.
Do the stoplamps continue to illuminate?
Yes
REMOVE the known good relay. GO to M8.
No
REMOVE the known good relay. INSTALL a new adaptive cruise control stoplamp relay. TEST the system for normal operation.
M8 CHECK THE STOPLAMP SWITCH RELAY COIL FOR A SHORT TO GROUND
- Disconnect: ABS Module C135.
- Measure the resistance between the adaptive cruise control stoplamp relay pin 2, circuit CLS44 (VT/BN), BJB (Battery Junction Box) face side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to M14.
No
REPAIR circuit CLS44 (VT/BN) for a short to ground. TEST the system for normal operation.
M9 CHECK THE SJB (Smart Junction Box) FOR A SHORT TO VOLTAGE
- Disconnect: SJB (Smart Junction Box) C2280B.
Does the high mounted stoplamp continue to illuminate?
Yes
If equipped with a TBC (Trailer Brake Control) module, GO to M10.
If not equipped with a TBC (Trailer Brake Control) module, GO to M11
No
GO to M13.
M10 CHECK THE TBC (Trailer Brake Control)
- Disconnect: TBC (Trailer Brake Control) Module C2142.
Does the high mounted stoplamp continue to illuminate?
Yes
GO to M11.
No
INSTALL a new TBC (Trailer Brake Control) module. TEST the system for normal operation.
M11 CHECK THE RFA (Remote Function Actuator) MODULE FOR A SHORT TO VOLTAGE
- Disconnect: RFA (Remote Function Actuator) Module C2153E.
Does the high mounted stoplamp continue to illuminate?
Yes
REPAIR circuit CCB08 (VT/WH) or circuit CLS43 (YE/GN) for a short to voltage. TEST the system for normal operation.
No
GO to M15.
M12 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PCM 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 PCM. 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.
M13 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION
- Disconnect all the SJB (Smart Junction Box) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB (Smart Junction Box) 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 SJB (Smart Junction Box). 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.
M14 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect the ABS module connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the ABS module connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new ABS 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.
M15 CHECK FOR CORRECT RFA (Remote Function Actuator) MODULE OPERATION
- Disconnect all the RFA (Remote Function Actuator) module connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the RFA (Remote Function Actuator) 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 RFA (Remote Function Actuator) 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.