5005646 JOHNSON Service Manual - English

Illustration 1 g01165076
Schematic for the circuit for the two-speed axle switch
In this configuration, the switch is wired directly to the ECM.
Note: The return wire for the two-speed axle switch may be connected to P1-3, to P1-5, or to P1-18.
Illustration 2 g01165080
Terminals on the P1 connector for the circuit for the two-speed axle switch
(5) Return
(6) Two-speed axle switch Test Step 1. Check the Configuration Parameters
Establish communication between Cat ET and the ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
Verify that the following configuration parameters are programmed to the correct value:
Two Speed Axle - Low Speed Range Axle Ratio
Nominal Axle Ratio - High Speed Range Axle Ratio
Two Speed Axle SwitchExpected Result:The parameters are programmed correctly.Results:
The parameters are programmed correctly. - Proceed to Test Step 2.
One or more of the parameters is not programmed correctly. - Repair: Program the correct values for the parameters. Test the operation of the speedometer on both axle ratios. If the speedometer is operating correctly, the problem is resolved.If the speedometer is not operating correctly and a J1939 device is used to send the status of the two-speed axle switch to the ECM, send the vehicle to an OEM dealer for repair.If the speedometer is not operating correctly and the two-speed axle switch is wired directly to the ECM, proceed to Test Step 2.Test Step 2. Check for a Short Circuit
Set the axle to the high ratio.
Inspect the seal around the signal wire and the return wire at the P1 connector. Verify that the seals are sealing correctly. Verify that the harness side of the ECM connector is clean and dry. Correct any problems. Replace parts, if necessary.
Pull on the signal wire and on the return wire in order to verify that the wire and the terminal are correctly installed. Correct any problems. Replace parts, if necessary.
Use two 7X-1710 Multimeter Probes to connect a voltmeter to terminal P1-6 and to the return terminal for the two-speed axle switch.
Read the voltage on the voltmeter.
Check the status of the "Two Speed Axle Switch" input on Cat ET. Expected Result:The voltage is approximately equal to the battery voltage. "Two Speed Axle Switch" indicates "Off".Results:
OK - There is not a short circuit. Proceed to Test Step 3.
Not OK - The voltage is approximately zero. "Two Speed Axle Switch" indicates "On". Proceed to Test Step 4.Test Step 3. Check for an Open Circuit
Set the axle to the low ratio.
Read the voltage on the voltmeter.
Check the status of the "Two Speed Axle Switch" input on Cat ET. Expected Result:The voltage is approximately zero. "Two Speed Axle Switch" indicates "On".Results:
OK - The voltage is approximately zero. "Two Speed Axle Switch" indicates "On". The circuit is operating correctly. However, there may be an intermittent problem. Proceed to Test Step 6.
Not OK - The voltage is approximately equal to battery voltage. "Two Speed Axle Switch" indicates "Off". Proceed to Test Step 5.
Not OK - The voltage is approximately zero. "Two Speed Axle Switch" indicates "Off". The input to the ECM indicates an "Off" condition. However, the ECM indicates that an "On" condition exists.Repair: There may be a problem with the ECM.Temporarily connect a test ECM. Refer to Troubleshooting, "Test ECM Mode". If the problem is resolved with the test ECM, connect the original ECM. If the problem is resolved with the test ECM and the problem returns with the original ECM, replace the original ECM.STOPTest Step 4. Check for a Short Circuit
Remove the signal wire from P1-6.
Inspect the terminal for moisture and for corrosion. Correct any problems. Replace parts, if necessary.
Check the status of the "Two Speed Axle Switch" input on Cat ET. Expected Result:"Two Speed Axle Switch" indicates "Off".Results:
OK - "Two Speed Axle Switch" indicates "Off". Insert the signal wire into the P1 connector. Pull on the wire in order to verify proper installation of the terminal. Proceed to Test Step 6.
Not OK - "Two Speed Axle Switch" indicates "On".Repair: Perform the following procedure:
Disconnect the P1 connector. Inspect the P1 and J1 connectors for moisture and for corrosion. Make repairs, if necessary.
Connect the P1 connector.
Check the status of the "Two Speed Axle Switch" input on Cat ET. If the problem is not resolved, Temporarily connect a test ECM. Refer to Troubleshooting, "Test ECM Mode". If the problem is resolved with the test ECM, connect the original ECM. If the problem is resolved with the test ECM and the problem returns with the original ECM, replace the original ECM.STOPTest Step 5. Check for Voltage at the Switch
Inspect the seal around the signal wire and the return wire at the connectors for the two-speed axle switch. Verify that the seals are sealing correctly. Correct any problems.
Pull on the wires in order to verify that the wires are correctly installed. Correct any problems. Replace parts, if necessary.
Connect a voltmeter to the wires at the harness connector for the two-speed axle switch.
Measure the voltage at the switch terminals. Expected Result:The voltage is approximately zero.Results:
OK - The voltage is approximately zero. There is an open circuit between the P1 connector and the switch. Set the axle to the low ratio. Proceed to Test Step 6.
Not OK - The voltage is approximately equal to the battery voltage.Repair: Perform the following procedure:
Disconnect the connectors for the two-speed axle switch.
Inspect the connectors and the terminals for moisture and for corrosion. Make repairs, if necessary.
Connect the connectors for the switch.
Measure the voltage at the switch terminals. If the voltage is approximately equal to zero, the problem may be resolved. Check the status of the "Two Speed Axle Switch" on Cat ET when the two-speed axle switch is in both positions. If the status of the switch matches the position of the switch, the problem is resolved. STOPIf the voltage is approximately equal to battery voltage, replace the two-speed axle switch. Verify that the problem is resolved.STOPTest Step 6. Perform the Wiggle Test for the Circuit for the Two-Speed Axle SwitchCarefully following this procedure is a good way to identify the root cause of intermittent problems.