PIPE AS 1741892 - Caterpillar

Illustration 1 g00678674
Schematic of the SPI Data Link
This diagnostic code is recorded when the speedometer/tachometer module has dropped off the SPI data link 10 times within a ten minute period. The event is active until communication is reliable for more than ten minutes. System Response:The result of this condition is the speedometer/tachometer module or the actual gear indicator may operate erratically during operation. The speedometer/tachometer module may not work at all. Test Step 1. INSPECT THE HARNESS CONNECTIONS.
Turn the disconnect switch to the OFF position.
Inspect the harness connections that are related to the SPI data link. Make sure that the connectors are clean and tight.
Check the mating of the harness connectors.
Check wires at the connector.
Check each wire for nicks or signs of abrasion in the insulation.
Check for moisture at the connector.
Check for dirty contacts or corroded contacts.
Check each pin and each socket. Expected Result:The machine harness connectors are tight and free of corrosion. Results:
OK - The machine harness connectors are tight and free of corrosion. Proceed to test step 2.
NOT OK - The machine harness connectors are NOT tight and free of corrosion. Repair: Repair the machine harness or replace the machine harness.STOPTest Step 2. CHECK FOR A SHORT TO +BATTERY.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the J1and J2 connectors from the ECM.
Disconnect the machine harness connectors from all of the display modules.
At the J1and J2 machine harness connectors for the ECM, measure the resistance between the contacts that are listed below:
Connector contact J1-1(wire 170-YL(Yellow)) and the "SPI Data Link circuit" contact J2-10 (wire C413-YL(Yellow)).
Connector contact J1-1 (wire 170-YL(Yellow)) and the "SPI Data Link circuit" contact J2-20 (wire C414-BU(Blue)).
Connector contact J1-1 (wire 170-YL(Yellow)) and the "SPI Data Link circuit" contact J2-28 (wire E708-PK(Pink)). Expected Result:The resistance is greater than 5000 ohms.Results:
OK - The resistance is greater than 5000 ohms. Proceed to test step 3.
NOT OK - The resistance is less than 5 ohms. The machine harness has failed.Repair: There is a short between the +battery and the circuits of the SPI data link in the machine harness. Replace the machine harness or repair the machine harness.STOPTest Step 3. CHECK FOR AN OPEN HARNESS.
The disconnect switch and the key start switch remain in the OFF position.
All the display modules remain disconnected from the machine harness.
Measure the resistance of the circuits of the SPI data link that are listed below:
Measure the resistance between connector contact J2-10 (wire C413-YL(Yellow)) to connector contact 4 (wire C413-YL(Yellow)) of the speedometer/tachometer module.
Measure the resistance between connector contact J2-20 (wire C414-BU(Blue)) to connector contact 5 (wire C414-BU(Blue)) of the speedometer/tachometer module.
Measure the resistance between connector contact J2-28 (wire E708-PK(Pink)) to connector contact 3 (wire E708-PK(Pink)) of the speedometer/tachometer module.Expected Result:The resistance is less than 5.0 ohms. Results:
OK - The resistance is less than 5.0 ohms. The circuit resistance is correct. Proceed to test step 4.
- The resistance is greater than 5000 ohms. There is an open in the machine harness.Repair: Repair the machine harness or Replace the machine