GASKET 7L0487 - Caterpillar

System Operation Description:The digital sensor supply provides power to all digital sensors. Digital sensors include the Left and Right Exhaust Temperature Sensors.The digital sensor supply is output short circuit protected. A short circuit to the Battery should not cause permanent damage to the circuit inside the ECM. The digital sensors are NOT protected from overvoltage.
Illustration 1 g00705333
SchematicTest Step 1. Check for connector damage.
Turn the breaker at the battery to the OFF position.
Turn the ECS to the OFF/RESET position.
Check the connectors and wiring for the following problems: damage, corrosion, abrasion and incorrect attachment .Expected Result:The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.Results:
OK - Proceed to test step 2.
Not OK - Repair: Repair the connectors and/or wiring or replace the connectors and/or wiring. Stop.Test Step 2. Check for a short circuit in the wiring harness.
Disconnect J1/P1 and J2/P2.
Disconnect all the digital sensors.
Measure the resistance between the digital supply P1-35 (A700-OR) and the digital return P1-29 (998-BR) .
Measure the resistance between the digital supply P1-35 (A700-OR) and engine ground.
Measure the resistance between the digital return P1-29 (998-BR) and engine ground.Expected Result:The resistance should be greater than 20,000 Ohms for each measurement.Results:
OK - Proceed to test step 3.
Not OK - Repair: Repair the connectors and/or wiring or replace the connectors and/or wiring. Verify the repair by rechecking for shorts in the harness. Stop.Test Step 3. Check the digital supply voltage at the ECM.
Reconnect the ECM connectors.
Turn the ECS to the ON position. The engine should be OFF.
Measure the voltage between the digital supply P1-35 (A700-OR) and the digital return P1-29 (998-BR).Expected Result:The supply voltage should be 8.0 0.5 VDC.Results:
OK - The digital sensor supply is producing the correct voltage. Proceed to test step 4.
Not OK - The digital sensor is not producing the correct voltage. Proceed to test step 5.Test Step 4. Check the digital sensor supply voltage at the sensor connector.
Measure the voltage between the digital supply terminal-A (A700-OR) and the terminal-B (998-BR) of all the digital sensors.Expected Result:The supply voltage should be 8.0 0.5 VDC.Results:
OK - The supply voltage is present at all of the digital sensor connectors. Proceed to test step 6.
Not OK - There is an open circuit in the harness or connectors.Repair: Repair the connectors and/or wiring or replace the connectors and/or wiring. Stop.Test Step 5. Perform the following test: Electrical Power SupplyResults:
REPAIRED, OK - Stop.
OK - Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM". Stop.Test Step 6. Check the digital sensors for short circuits.
Connect one digital sensor.
Check the digital sensor supply voltage between the digital supply terminal-A (A700-OR) and the digital return terminal-B (998-BR). Repeat this step with all of the digital sensors.
Turn the ECS to the OFF/RESET position.Expected Result:The supply voltage should be 8.0 0.5 VDC.Results:
OK - The digital sensor supply is OK. The harness is OK. Stop.
Not OK - The sensor may be internally shorted.Repair: Temporarily connect a new sensor. Verify that the new sensor solves the problem before permanently installing