Disconnect the original equipment manufacturer (OEM) pressure sensor connector from the OEM harness. Disconnect the OEM harness connector from the electronic control module (ECM).
Check the OEM pressure sensor connector and OEM harness connectors for broken, bare, or melted wires; loose, dirty, damaged, or missing pins; and other visible signs of damage.
The leads must fit tightly in the connector without expanding the pins in the connector otherwise the connector will be damaged.
Disconnect the OEM harness connector from the ECM. Disconnect the OEM pressure sensor from the OEM harness. Set the multimeter to measure resistance.
Insert a test lead into the OEM pressure sensor signal pin of the OEM harness connector. Connect the alligator clip to a multimeter probe. Insert the second test lead to the signal pin of the OEM pressure sensor harness connector and connect the clip to the other multimeter probe. Measure the resistance.
Repeat the resistance check for the return wire. Measure the resistance from the OEM pressure sensor return pin of the OEM harness connector to the OEM pressure sensor return pin of the harness connector.
The multimeter must show a measurement of 10 ohms or less (closed circuit).
If the measured value is more than 10 ohms, there is an open circuit in the return wire.
Repair or replace the OEM harness. Refer to Procedure 019-071.
Repeat the resistance check for the 5 volt supply wire. Measure the resistance from the OEM pressure sensor 5 volt supply pin of the OEM harness connector to the OEM pressure sensor 5 volt supply pin of the harness connector.
The multimeter must show a measurement of 10 ohms or less (closed circuit).
If the measured value is more than 10 ohms, there is an open circuit in the 5 volt supply wire.
Repair or replace the OEM harness. Refer to Procedure 019-071.
Disconnect the OEM harness connector from the ECM. Disconnect the OEM pressure sensor from the OEM harness. Set the multimeter to measure resistance.
Insert the test lead into the OEM pressure sensor signal pin of the OEM harness connector. Touch the other multimeter probe to engine block ground. Measure the resistance.
Repeat the short-to-ground check for the return wire. Measure the resistance from the OEM pressure sensor return pin of the OEM harness connector to engine block ground.
The multimeter must show a measurement of 100k ohms or more (open circuit).
If the measured value is less than 100k ohms, there is a short circuit to ground in the return wire.
Repair or replace the OEM harness. Refer to Procedure 019-071.
Repeat the short-to-ground check for the 5 volt supply wire. Measure the resistance from the OEM pressure sensor 5 volt supply pin of the OEM harness connector to engine block ground.
The multimeter must show a measurement of 100k ohms or more (open circuit).
If the measured value is less than 100k ohms, there is a short circuit to ground in the 5 volt supply wire.
Repair or replace the OEM harness. Refer to Procedure 019-071.
Disconnect the OEM harness connector from the ECM. Disconnect the OEM pressure sensor from the OEM harness. Set the multimeter to measure VDC. Turn the vehicle keyswitch to the ON position.
Insert the test lead connected to the positive (+) multimeter probe into the OEM pressure sensor signal pin of the OEM harness connector. Touch the negative (-) multimeter probe to engine block ground and measure the voltage.
Repeat the short to external voltage source check for the return wire. Measure the voltage from the OEM pressure sensor return pin of the OEM harness connector to engine block ground.
If there is voltage present, there is a short circuit from the return wire to an external voltage source.
Repair or replace the OEM harness. Refer to Procedure 019-071.
Repeat the short to external voltage source check for the 5 volt supply wire. Measure the voltage from the OEM pressure sensor 5 volt supply pin of the OEM harness connector to engine block ground.
The multimeter must show a voltage of less than 5.5 VDC. If the voltage is greater than 5.5 VDC, there is a short circuit from the 5 volt supply wire to an external voltage source.
Repair or replace the OEM harness. Refer to Procedure 019-071.
Hello, I'm Jack, a diesel engine fan and a blogger. I write about how to fix and improve diesel engines, from cars to trucks to generators. I also review the newest models and innovations in the diesel market. If you are interested in learning more about diesel engines, check out my blog and leave your feedback.
View all posts by Jack