Electronic Control System Signature, ISX and QSX15 Engines - 019-108 Intermediate Speed Control Validation Switch

Resistance Check
Check for Short Circuit to Ground
Check for Short Circuit from Pin to Pin

Resistance Check

TOC

Disconnect the OEM harness connector from the ECM.

Use test lead, Part No. 3822758, on the ECM connectors.

Disconnect the bulkhead connector.

Measure the resistance from pin 23 of the OEM harness connector to the corresponding pin of the bulkhead connector (refer to the OEM troubleshooting and repair manual). The multimeter

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

If the circuit is

not closed, repair or replace the wiring harness. Refer to Procedure

019-043.

SMALL | MEDIUM | LARGE

Measure the resistance from pin 25 of the OEM harness connector to the corresponding pin of the bulkhead connector (refer to the OEM troubleshooting and repair manual). The multimeter

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

If the circuit is

not closed, repair or replace the wiring harness. Refer to Procedure

019-043.

SMALL | MEDIUM | LARGE

Measure the resistance from pin 33 of the OEM harness connector to the corresponding pin of the bulkhead connector (refer to the OEM troubleshooting and repair manual). The multimeter

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

If the circuit is

not closed, repair or replace the wiring harness. Refer to Procedure

019-043.

If the OEM harness on the engine side of the bulkhead connector passes the above resistance checks, check the resistance of the vehicle side of the bulkhead connector. Refer to the vehicle manufacturer’s instructions.

SMALL | MEDIUM | LARGE

Check for Short Circuit to Ground

TOC

Disconnect the OEM harness connector from the ECM.

Use test lead, Part No. 3822758.

Move the ISC switch to the center (OFF) position.

Measure the resistance from pins 23, 25, and 33 to the engine block. The multimeter

must show 100k ohms or more.

If the circuit is

not open, check for short circuit to ground in the OEM wiring harness, provided the switch has been checked previously.

SMALL | MEDIUM | LARGE

Disconnect the bulkhead harness connector.

Measure the resistance from the ECM connector pins 23, 25, and 33 to the engine block. The multimeter

must show 100k ohms or more.

If the circuit is

not open, check for short circuit to ground in the vehicle side of the bulkhead connector. Refer to the vehicle manufacturer’s instructions.

SMALL | MEDIUM | LARGE

Check for Short Circuit from Pin to Pin

TOC

Disconnect the OEM harness connector from the ECM.

Use test lead, Part No. 3822758 on the ECM connector.

Measure the resistance from pin 23 of the OEM harness connector to all other pins in the connector. The multimeter

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

Measure the resistance from pin 33 of the OEM harness connector to all other pins in the connector. The multimeter

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

Measure the resistance from pin 25 of the OEM harness connector to all other pins in the connector. The multimeter

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

If the circuit is

not open, check for a short circuit from pin to pin on the engine side of the bulkhead connector, provided the switch has been checked earlier.

SMALL | MEDIUM | LARGE

Disconnect the bulkhead connector.

Measure the resistance from pin 23 of the OEM harness connector to all other pins in the connector. The multimeter

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

Measure the resistance from pin 33 of the OEM harness connector to all other pins in the connector. The multimeter

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

Measure the resistance from pin 25 of the OEM harness connector to all other pins in the connector. The multimeter

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

If the circuit is

not open, check for a short circuit from pin to pin on the vehicle side of the bulkhead connector. Refer to the vehicle manufacturer’s instructions.

Connect all components after completing the repair.