SCREW 0055402 - Caterpillar

Illustration 4 g03132596
Typical view of the pin locations on the P1 connector
(13) CAN B+
(17) CAN C+
(18) CAN C-
(21) CAN B-
(25) CAN A+
(26) CAN A-
Illustration 5 g03132736
Typical view of the pin locations on the P2 connector
(23) CAN A+
(31) CAN A-Complete the procedure in the order in which the steps are listed.
Table 2
Troubleshooting Test Steps Values Results
1. Check for Associated Diagnostic Trouble Codes
A. Establish communication between the electronic service tool and the ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.
B. Download the "Warranty Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes.
Troubleshoot any associated diagnostic codes that are present before continuing with this procedure.
Associated Codes
Result: Another diagnostic trouble code is not active or logged.
Proceed to Test Step 2.
Result: Another code is active or logged.
Repair: Troubleshoot the other codes before continuing with this procedure.
Refer to Troubleshooting, "Diagnostic Trouble Codes" to troubleshoot the other diagnostic code.
2. Use the "System Communication Status" to Determine the Communication Issue
A. In the electronic service tool, click the "Diagnostics" tab on the tool bar.
B. Select the "System Communication Status" option from the drop-down list.
Note: The Aftertreatment #1 Intake NOx Level Sensor is displayed as Aftertreatment #1 Information #1 in some versions of software.
Component Identified
Result: A -9 or -2 code is active.
Repair: Refer to the above -9 detected problems for more information.
Proceed to Test Step 3.
3. Use the System Communication Status to Determine the Cause
A. Determine if both ECM 1 and ECM 2 are present in the "ECM's" column (1) within the "System Communication Status" screen.
Note: The Aftertreatment #1 Intake NOx Level Sensor is displayed as Aftertreatment #1 Information #1 in some versions of software.
Component Identified
Result: ECM 1 and ECM 2 are both present.
Record the devices identified as ECM 1 and ECM 2 in column 1.
Proceed to Test Step 4.
Result: Only ECM 1 is present.
Record the device identified as ECM 1 in column 1.
Proceed to Test Step 5.
4. Check the Resistance of the Data link
A. Turn the keyswitch to the OFF position.
B. Measure the resistance of the datalink between ECM 2 datalink (+) wire and the datalink (-) wire on the wiring harness connector of ECM 2. Refer to the appropriate wiring diagram.
Note: If ECM 2 is the Dosing Control Unit (DCU), the 398-5063 Break-out Connector must be used to prevent damage to the DCU connector.
60+/-10 Ohms
Result: The resistance is less than 50 Ohms.
There are more than two terminating resistors installed in the wiring harness or a short circuit has been detected.
Repair: Repair or replace parts as necessary.
Proceed to Test Step 8.
Result: The resistance is 60 10 Ohms.
The terminating resistors are OK.
Proceed to Test Step 5.
Result: The resistance is 120 10 Ohms.
There is a problem with a terminating resistor.
Repair: Check the resistance on each terminating resistor. Replace the failed terminating resistor.
Proceed to Test Step 8.
Result: The resistance is greater than 130 Ohms.
There is a problem with both terminating resistors or an open circuit has been detected.
Repair: Determine the cause of the problem. Repair the problem, when possible. Replace parts, if necessary. Verify that