Pinpoint Test AB: A Customer Access Turn Signal Input Is Inoperative Or Always On
Commercial Service Equipment
Pinpoint Test AB: A Customer Access Turn Signal Input Is Inoperative Or Always On
Refer to Wiring Diagrams Set 90, Turn Signal/Stop/Hazard Lamps for schematic and connector information. Electrical Diagrams
Normal Operation
When the vehicle rear turn lamps are illuminated, voltage is provided to a corresponding turn relay coil. When the turn relay is energized, voltage is provided to the customer access block connector.
This pinpoint test is intended to diagnose the following:
- Customer-installed components or circuitry
- Fuse
- Wiring, terminals or connectors
- Turn relay
PINPOINT TEST AB : A CUSTOMER ACCESS TURN SIGNAL INPUT IS INOPERATIVE OR ALWAYS ON
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
AB1 CHECK REAR TURN LAMP OPERATION
- Ignition ON.
- Activate the hazard lamp function and observe the rear turn lamps.
Do the rear turn lamps operate correctly?
Yes
If a turn signal input is always on, GO to AB2.
If both turn signal inputs are inoperative, VERIFY the BJB (Battery Junction Box) fuse 35 (15A) (early build) or fuse 10 (25A) (late build) is OK. If OK, GO to AB4. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Electrical Diagrams
If an individual turn signal input is inoperative, VERIFY the CJB (Central Junction Box) fuse 173 (10A) (left turn signal) or fuse 172 (10A) (right turn signal) is OK. If OK, GO to AB5. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Electrical Diagrams
No
GO to Pinpoint Test N. Pinpoint Test N: One Turn Signal/Hazard Lamp Is Inoperative/Always On
AB2 CHECK THE TURN RELAY OUTPUT
- Ignition OFF.
- Deactivate the hazard lamp function.
- Disconnect: Customer Access Block Connector C3509.
- Ignition ON.
- Measure the voltage between the customer access block connector C3509-1 (left turn input), circuit 30S-LG12 (RD/YE), harness side and ground; or between the customer access block connector C3509-5 (right turn input), circuit 30S-LG19 (RD/BU), harness side and ground.
Is any voltage present?
Yes
GO to AB3.
No
The vehicle is operating correctly. The concern is with the customer-installed components or circuitry.
AB3 CHECK THE TURN RELAY OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: Suspect Turn Relay.
- Ignition ON.
- Measure the voltage between the customer access block connector C3509-5 (left turn input), circuit 30S-LG19 (RD/BU), harness side and ground; or between the customer access block connector C3509-1 (right turn input), circuit 30S-LG12 (RD/YE), harness side and ground.
Is any voltage present?
Yes
REPAIR the circuit in question. TEST the system for normal operation.
No
INSTALL a new turn relay for the relay in question. TEST the system for normal operation.
AB4 CHECK THE TURN RELAY VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Ignition OFF.
- Deactivate the hazard lamp function.
- Disconnect: Left Turn Relay.
- Measure the voltage between the left turn relay pin 3, circuit 30-LG12 (RD), harness side and ground.
Is the voltage greater than 10 volts?
Yes
REPAIR the turn relay ground circuit for an open. TEST the system for normal operation.
No
REPAIR the turn relay voltage supply circuit for an open. TEST the system for normal operation.
AB5 CHECK THE TURN RELAY
- Ignition OFF.
- Deactivate the hazard lamp function.
- Disconnect: Suspect Turn Relay.
- Substitute a known good relay for the turn relay in question.
- Ignition ON.
- Activate the hazard lamp function.
Does the turn signal input operate correctly?
Yes
REMOVE the known good relay. INSTALL a new turn relay for the relay in question. TEST the system for normal operation.
No
REMOVE the known good relay. GO to AB6.
AB6 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE TURN RELAY FOR AN OPEN
- Ignition OFF.
- Deactivate the hazard lamp function.
- For a left turn signal input, measure the voltage between the left turn relay pin 3, circuit 30-LG12 (RD), harness side and ground.
- For a right turn signal input, measure the voltage between the right turn relay pin 3, circuit 30-LG19 (RD), harness side and ground.
Is the voltage greater than 10 volts?
Yes
GO to AB7.
No
REPAIR the circuit in question. TEST the system for normal operation.
AB7 CHECK THE TURN RELAY GROUND CIRCUIT FOR AN OPEN
- For a left turn signal input, measure the voltage between the left turn relay pin 3, circuit 30-LG12 (RD), harness side and the left turn relay pin 2, circuit 31-LG12 (BK), harness side.
- For a right turn signal input, measure the voltage between the right turn relay pin 3, circuit 30-LG19 (RD), harness side and the right turn relay pin 2, circuit 31-LG19 (BK), harness side.
Is the voltage greater than 10 volts?
Yes
GO to AB8.
No
REPAIR the ground circuit in question. TEST the system for normal operation.
AB8 CHECK THE TURN SIGNAL CIRCUIT TO THE TURN RELAY COIL FOR AN OPEN
- Ignition ON.
- Activate the hazard lamp function.
- For a left turn signal input, measure the voltage between the left turn relay pin 1, circuit 49S-LG12 (BU), harness side and ground.
- For a right turn signal input, measure the voltage between the right turn relay pin 1, circuit 49S-LG19 (BU/RD), harness side and ground.
Does the voltage alternate from 0 to greater than 10 volts?
Yes
GO to AB9.
No
REPAIR the circuit in question. TEST the system for normal operation.
AB9 CHECK THE TURN SIGNAL CIRCUIT TO THE CUSTOMER ACCESS CONNECTOR FOR AN OPEN
- Ignition OFF.
- Deactivate the hazard lamp function.
- Connect: Suspect Turn Relay.
- Disconnect: Customer Access Connector C3509.
- Ignition ON.
- Activate the hazard lamp function.
- Measure the voltage between the customer access block connector C3509-1 (left turn input), circuit 30S-LG12 (RD/YE), harness side and ground; or between the customer access block connector C3509-5 (right turn input), circuit 30S-LG19 (RD/BU), harness side and ground.
Does the voltage alternate between 0 and greater than 10 volts?
Yes
The vehicle is operating correctly. The concern is with the customer-installed components or circuitry.
No
REPAIR the circuit in question. TEST the system for normal operation.