HOSE AS 8X6169 - Caterpillar

The mode selection switch uses resistors to modify the voltage signal from the ECM. The resistance of the switch changes dependent on which position the switch is in. The ECM uses the signal voltage to determine which mode has been selected.
Illustration 1 g03117957
View of the signal voltage range for the mode selection switch
Note: Position (4) is not available on the mode selection switch. If the signal voltage range is between 3.7 and 4.4 VDC, the mode that is selected will be the same as position (3).
Illustration 2 g03728025
Typical example of the schematic for the mode selection switch
Not all connectors are shown. Refer to the Electrical Schematic for the application.
Illustration 3 g02723018
Typical view of the pin locations on the P1 connector for the mode selection switch
(55) Mode selection switch signal
(77) Mode selection switch ground
Table 2
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Thoroughly inspect the terminal connections on the P1/J1 connector.
B. Thoroughly inspect the connector for the mode selection switch.
C. Refer to Troubleshooting, "Electrical Connectors - Inspect".
D. Perform a 30 N (6.7 lb) pull test on each of the wires in the connectors that are associated with the mode selection switch.
E. Check the harness for abrasions and for pinch points from the switch back to the ECM.
Damaged wire or connector
Result: A damaged wire or damaged connector was not found.
Proceed to Test Step 2.
Result: A damaged wire or damaged connector was found.
Repair: Repair the damaged wire or the damaged connector.
Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault.
2. Check for Active or Recently Logged Diagnostic Codes
A. Turn the keyswitch to the OFF position.
B. Connect the electronic service tool to the diagnostic connector.
C. Turn the keyswitch to the ON position. Do not start the engine.
D. Check for active diagnostic codes with the mode selection switch in each position. Wait at least 10 seconds with the switch in each position for activation of the diagnostic codes.
Diagnostic Trouble Codes
Result: A 2880-4 diagnostic code is active.
Proceed to Test Step 3.
Result: A 2880-3 diagnostic code is active.
Proceed to Test Step 4.
Result: A 2880-2 diagnostic code is active.
Proceed to Test Step 5.
3. Create an Open Circuit at the Switch
A. Turn the keyswitch to the OFF position.
B. Disconnect the mode selection switch.
C. Turn the keyswitch to the ON position.
D. Use the electronic service tool to check for an active 2880 diagnostic code. Wait at least 10 seconds for activation of the diagnostic codes.
E. Turn the keyswitch to the OFF position.
Diagnostic codes
Result: A 2880-3 diagnostic code is active with the switch disconnected.
Repair: Replace the mode selection switch.
Use the electronic service tool to clear all logged diagnostic codes and verify that the repair eliminates the fault.
Result: A 2880-4 diagnostic code is still active with the switch disconnected.
Reconnect the switch and proceed to Test Step 7.
4. Create a Short at the Switch Connector
A. Turn the keyswitch to the OFF position.
B. Disconnect the mode selection switch.
C. Fabricate a jumper wire and install the jumper wire between the two harness connector terminals for the