019-055   Idle Validation Switch Circuit

CAUTION  To reduce the possibility of connector damage, do not use probes or leads other than Part Number 3822758. The leads must fit tightly in the connector without expanding the pins in the connector.

Disconnect the OEM harness connector from the ECM. Refer to Procedure

019-071.

Insert a test lead into pin 10 (switch common +5-VDC supply) of the OEM harness connector. Insert the other test lead into pin 6 (active idle signal). Connect the alligator clips to the multimeter probes.

Make sure the idle validation switch is connected to the circuit. Make sure the foot pedal is in the idle (up) position. Measure the resistance.

The multimeter

must show 10 ohms or less for separate sensor/switch pedals and 125 ohms or less for integrated sensor/switch pedals.

Slowly depress the foot pedal and measure the resistance. If the resistance is greater than specified, replace the IVS.

The multimeter

must show an open circuit (100k ohms or more when depressed to the OFF-IDLE zone).

Move the test lead from pin 6 to pin 9 (active off-idle signal). Slowly depress the foot pedal and measure the resistance.

The multimeter

must show 10 ohms or less for separate sensor/switch pedals and 125 ohms or less for integrated sensor/switch pedals when in the OFF-IDLE zone of the pedal travel.

Let the foot pedal return to the idle (up) position and measure the resistance.

The multimeter

must show an open circuit (100k ohms or more) when in the ON-IDLE zone.

If the resistance values are

not within the specifications, there is a problem in the OEM harness, provided the idle validation switch has been previously checked.

If the resistance values are correct, the idle validation switch circuit

must still be checked for a short to ground, a short from pin to pin, and a short to external supply voltage.

NOTE: When checking the OEM harness, examine the bulkhead connector and other connectors in the circuit for corrosion or damage to the IVS terminals.

To isolate the idle validation switch circuit when checking for a short circuit, turn all cab panel switches to the OFF or neutral position.

Set the service brake using the trailer brake hand valve. Make sure there is enough air pressure to activate the brake pressure switch.

Disconnect the idle validation switch from the foot pedal and disconnect the clutch switch.

Install a test lead into pin 6 (active idle signal). Clip the lead to the multimeter. Touch the other multimeter probe to ground and measure the resistance.

The multimeter

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

Move the test lead from pin 6 to pin 9 (active off-idle signal). Touch the other multimeter lead to ground and measure the resistance.

The multimeter

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

Move the test lead from pin 9 to pin 10 (switch common +5-VDC supply). Touch the other multimeter lead to ground and measure the resistance.

The multimeter

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

If

any of the three resistance measurements are

not correct, there is a short circuit between that wire and ground. Repair the OEM harness according to the vehicle manufacturer’s instructions.

Connect all components after the repair is complete.

Isolate the idle validation switch circuit by setting the switches and pedals in the same position as the previous procedure.

Insert a test lead into pin 6. Insert the other test lead into pin 1. Clip the leads to the multimeter probes and measure the resistance.

The multimeter

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

Move the test lead from pin 1 to pin 2, then pin 3.

The multimeter

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

If the multimeter shows a closed circuit in any pin, there is a short circuit between wire number 6 (active idle circuit) and any other wire that measured a closed circuit. Repair the OEM harness according to the vehicle manufacturer’s procedures.

Connect the clutch switch and idle validation switch when repair is completed.

Move the test lead from pin 6 to pin 9 (active off-idle signal). Insert the other test lead into pin 1 and measure the resistance.

The multimeter

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

Move the test lead from pin 1 to pin 2, then pin 3.

The multimeter

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

If the multimeter shows a closed circuit in any pin, there is a short circuit between wire number 9 and any other wire that measured a closed circuit. Repair the OEM harness according to the vehicle manufacturer’s procedures.

Connect the clutch switch and idle validation switch when repair is completed.

Move the test lead from pin 9 to pin 10 (switch common +5-VDC supply). Insert the other test lead into pin 1 and measure the resistance.

The multimeter

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

Move the test lead from pin 1 to pin 2, then to pin 3.

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

If the multimeter shows a closed circuit in any pin, there is a short circuit between wire number 10 and any other wire that measured closed circuit. Repair the OEM harness according to the vehicle manufacturer’s procedures.

Connect the clutch switch and idle validation switch when repair is completed.

Isolate the idle validation switch circuits by setting the switches and pedals to the same position as in the previous procedure.

Turn keyswitch ON. Adjust the multimeter to measure voltage. Insert a test lead into pin 6 (active idle signal). Clip the lead to the multimeter positive (+) probe. Connect the multimeter negative (-) probe to ground and measure the voltage.

The voltage

must be 1.5 VDC or less.

Move the test lead from pin 6 to pin 9 (active off-idle signal). Touch the multimeter negative (-) lead to ground and measure the voltage.

The voltage

must be 1.5 VDC or less.

Move the test lead from pin 9 to pin 10 (switch common +5-VDC supply). Touch the multimeter negative (-) lead to ground and measure the voltage.

The voltage

must be 1.5 VDC or less.

If more than 1.5 VDC are measured at any pin, there is a short circuit between that pin and a wire carrying power in the OEM harness. Repair the OEM harness according to the manufacturer’s instructions.

Connect all components after the repair is complete.