CM2150 Electronic Control System – 019-194   Exhaust Brake ON/OFF Switch Circuit

CAUTION  The leads must fit tightly in the connector without expanding the pins in the connector otherwise the connector will be damaged.

If INSITE™ electronic service tool is available, monitor the exhaust brake switch circuit for proper operation.

If
not, follow the troubleshooting procedures in this section.

Disconnect the OEM harness from the ECM connector.

Insert the appropriate test lead into exhaust brake ON/OFF switch input pin of the OEM harness connector.

Insert the other appropriate test lead into switch return pin of the connector.

Set the exhaust brake switch to the ON position.

The multimeter
must show a closed circuit (10 ohms or less).

Set the exhaust brake switch to the OFF position.

The multimeter
must show an open circuit (100k ohms or more).

If the resistance values are
not correct, make sure exhaust brake ON/OFF switch input pin and the battery positive (+) bus to switch return pin are properly installed on the switch.

If both wires are correctly installed, inspect exhaust brake ON/OFF switch input pin and the battery positive (+) bus to switch return pin for open circuits to ground and short circuits to other pins, provided the switch has been previously checked.

If the resistance values are correct in the previous checks, exhaust brake ON/OFF switch input pin and switch return pin
must still be checked for short circuits to ground and short circuits from pin-to-pin.

To isolate the exhaust brake circuit when checking for an electrical short, turn all cab switches to the OFF or NEUTRAL position.

If INSITE™ electronic service tool is available, monitor the engine brake ON/OFF switch circuit for proper operation.

If
not, follow the troubleshooting procedures in this section.

Disconnect the OEM harness from the ECM connector.

Insert the appropriate test lead into exhaust brake ON/OFF switch input pin of the OEM harness connector. Touch the other multimeter probe to engine block ground. Measure the resistance.

The multimeter
must show an open circuit (100k ohms or more).

If the resistance value is
not correct, there is a short circuit to ground in the harness.

Repair or replace the OEM harness. Refer to Procedure
019-071.

Touch one multimeter probe to the engine block. Insert the other multimeter probe with attached appropriate test lead into switch return pin of the OEM harness connector. Measure the resistance.

The multimeter
must show an open circuit (100k ohms or more).

If the resistance value is
not correct, there is a short circuit to ground in the harness. Repair or replace the OEM harness. Refer to Procedure
019-071.

If the resistance value is correct in the previous checks, the exhaust brake ON/OFF switch input pin
must still be checked for short circuits from pin-to-pin.

Isolate the switch circuit as in the previous section.

Insert the appropriate test lead into exhaust brake ON/OFF switch input pin of the OEM harness connector.

Insert the other appropriate test lead into pin 1 of the connector. Connect the alligator clips to the multimeter probes. Measure the resistance.

The multimeter
must show an open circuit (100k ohms or more).

Remove the lead and check all other pins.

The multimeter
must show an open circuit (100k ohms or more).

If the circuit is
not open, there is a short circuit between the wire connected to exhaust brake ON/OFF switch input pin and any pin that measured less than 100k ohms.

Repair or replace the OEM harness. Refer to (Procedure
019-071).

Insert the test lead into switch return pin of the OEM harness connector. Check all pins of the harness connector. Measure the resistance.

The multimeter
must show an open circuit (100k ohms or more) at all pins.

If the circuit is
not open, there is a short circuit to ground in the positive switch supply bus, provided the switch has been previously checked.

Repair or replace the wiring connected to switch return pin in the OEM harness. Refer to Procedure
019-071.