HUB-IMPELLER 2638579 - Caterpillar

Illustration 1 g00701181
Schematic Of The Speed Mode Switch
Table 1
CIRCUIT CONTINUITY - CID 0589 SPEED MODE SWITCH    
ECM
Contact     Switch Contact     Wire Number     Switch Status    
Travel Mode Work Mode    
D-25, N/O (1)     N/O     P985-WH     R (2)     O (3)    
D-26, N/C (4)     N/C     P986-PU     O     R    
D-15
Return     COM     G939-PK     R     R    
( 1 ) N/O = Normally Open.
( 2 ) R = Return (continuity to return or ground)
( 3 ) O = Open (no continuity to return or ground)
( 4 ) N/C = Normally Closed.This switch has two inputs to the ECM. The inputs are N/O and N/C. During normal operation, one of the inputs is open and the other input is grounded. Table 1 shows the continuity of each switch circuit for the two positions of the switch. When a circuit is measured with a voltmeter, an open circuit will measure approximately 5 VDC and a closed circuit will measure approximately 0 VDC. When both of the inputs are in the same state at the same time, a failure is detected. An FMI 04 is recorded when the status of the N/O input and N/C input is grounded.The possible causes of this diagnostic code are listed:
The N/O circuit (wire P985-WH) is shorted to ground.
The N/C circuit (wire P986-PU) is shorted to ground.
The speed mode switch has failed.
The ECM has failed. This is unlikely.Note: Ensure that CID 0589 FMI 04 is on hold and that the diagnostic code is active. The "SERV CODE" should be showing. The diagnostic code will only be present when the speed mode switch is in the position that causes both inputs to be closed at the same time. If "SERV CODE" is NOT showing, move the speed mode switch to the position that causes "SERV CODE" to show.System Response:When this diagnostic code occurs a warning (Category 1) is shown on the monitor. The machine will go into "TRAVEL" mode when the transmission lever is in the PARK position.Test Step 1. CHECK FOR A SHORT TO GROUND.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the B and D machine harness connectors from the ECM.
At the D machine harness connector, measure the resistance from contact D-26 and contact D-25 to all sources of ground. The sources of ground are contacts: D-2 (202-BK), D-7 (975-WH), D-15 (G939-PK) and frame ground.Expected Result:The resistance measurement should be greater than 5000 ohms for each measurement.Results:
OK - The resistance measurement is greater than 5000 ohms for each measurement. Proceed to test step 2.
NOT OK - The resistance measurement is not 5000 ohms for one or more of the measurements.Repair: The short is in the circuit with the low resistance measurement. Repair the harness or replace the harness. Verify that the problem has been corrected. Stop.Test Step 2. CHECK THE RESISTANCE OF THE SWITCH.
The key start switch and the disconnect switch remain in the OFF position.
The B and D