CAN / J1939 TEST

This guide will help determine if there is an issue with the CAN / J1939 Data Link.

Note: Remember to check resistance with key in the off position.

Pin A= ground

Pin C= J1939 +

Pin D= J1939 –

Checking Battery Voltage

Make sure the voltage of the battery (batteries) is at least 11V before continuing with this test.

9-Pin Connectors

Use pins A and B to check for battery voltage

OBD2 connectors

Use pins 16(+) and 4,5 (-)

Maintain the positive lead of the multimeter on pin 16 (+). Check the grounds on pins 4 and 5(-).

Checking J1939 Data Link Voltage (Twisted pair).

Pin A (-) and C (+)

Pin A (-) and D (+)

Looking for 2.5V (+ – 1V)

Checking for Resistance.

Pin C and D

Looking for 60 Ohm. If the result is OL then a break in the wire is present

By following these steps, you can assess the J1939 Data Link’s condition and identify any potential issues related to connection, voltage, or resistance. Should any discrepancies be discovered during the testing, further investigation and repairs may be necessary using OEM literature to ensure proper functionality of the J1939 Data Link.

This guide is designed to assist in diagnosing potential issues with the J1939 Data Link.

Important Note: Remember to check the resistance with the key in the off position.

Pin A: ground.

Pin C: J1939 + (positive).

Pin D: J1939 – (negative).

Steps to Follow:

Checking Battery Voltage:

Before proceeding with the test, ensure the voltage of the battery (or batteries) is at least 11V.

Using 9-Pin Connectors:

To check for battery voltage, utilize pins A and B.

Using OBD2 Connectors:

To check for battery voltage, use pins 16(+) and 4,5 (-).

Keep the positive lead of the multimeter on pin 16 (+) and inspect the grounds on pins 4 & 5(-).

Checking J1939 Data Link Voltage (Twisted Pair):

Measure voltage between Pin A (-) and Pin C (+).

Measure voltage between Pin A (-) and Pin D (+).

The target voltage range is approximately 2.5V (+ – 1V).

Checking for Resistance:

Measure the resistance between Pin C and Pin D.

The expected resistance reading is 60 Ohms. If the result shows “OL,” it indicates a break in the wire.

By following these steps, you can assess the J1939 Data Link’s condition and identify any potential issues related to connection, voltage, or resistance. Should any discrepancies be discovered during the testing, further investigation and repairs using OEM information may be necessary to ensure proper functionality of the J1939 Data Link.