C7.1 Engines Caterpillar

Use this procedure if the electronic service tool will not communicate with the ECM through the data link. Also use this procedure if the following code is active or logged.

Table 1

Diagnostic Trouble Codes for the Data Link Circuit
J1939 Code	CDL Code	Code Description	Comments
-	248-9	Cat Data Link: Abnormal Update Rate	The engine ECM detects a loss of communications with the Cat data bus. The ECM will log the diagnostic code. The engine will not start.

The following background information is related to this procedure:

The data link is the standard data link that is used by the ECM in order to communicate with the electronic service tool.

The ECM provides multiple connections for the data link. The technician must ensure that the correct connector is being tested. The connection that is used is dependent on the application.

If the diagnostic connector is off the engine, the positive data link signal will be from P1:20 to pin "D" of the diagnostic connector. The negative data link signal will be from P1:28 to pin "E" of the diagnostic connector.

If the diagnostic connector is on the engine, the positive data link signal will be from P2:47 to pin "D" of the diagnostic connector. The negative data link signal will be from P2:55 to pin "E" of the diagnostic connector.

The following information refers to the pin number. Ensure that the correct connector is used.

Communication

The electronic service tool may indicate the following error message:

The version of the ECM is not recognized and the integrity of the changed parameters and displayed data is not guaranteed.

This message will indicate that the version of the software that is in the electronic service tool is obsolete. Install the latest version of the software for the electronic service tool in order to rectify the fault.

Illustration 1	g03705762
Schematic of the diagnostic connector and the data link connector for a diagnostic connector that is mounted off engine

Illustration 2	g03705767
Schematic of the diagnostic connector and the data link connector for an engine mounted diagnostic connector

Illustration 3	g03134661
P1 pin locations for the diagnostic connector (20) Data link + (28) Data link -

Illustration 4	g03134662
Typical view of the P2 pin locations for the diagnostic connector (47) Data link + (55) Data link - (56) Voltage supply (diagnostic connector) (64) Return (diagnostic connector)

Complete the procedure in the order in which the steps are listed.

Table 2

Troubleshooting Test Steps	Values	Results
1. Inspect Electrical Connectors and Wiring A. Turn the keyswitch to the OFF position. B. Inspect the connectors in the circuit for the data link. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details. C. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the CAN data link. D. Check the screw for the P1 and P2 ECM connectors for correct torque of 6 N·m (53 lb in). E. Check all of the wiring associated with the data link for abrasions and pinch points.	Damaged wire or connector	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. Result: A damaged wire or damaged connector was not found. Proceed to Test Step 2.
2. Determine the Type of Fault in the Data Link A. Connect the electronic service tool to the diagnostic connector that is on the engine harness or on the application. Repair: Turn the keyswitch to the ON position.	Power to the comms adapter	Result: The power lamp illuminates on the communications adapter. The communications adapter is currently receiving the correct voltage. Proceed to Test Step 5. Result: The power lamp is not illuminated on the communications adapter. The communications adapter is not currently receiving the correct voltage. Proceed to Test Step 3.
3. Check the Battery Voltage at the Diagnostic Connector A. Turn the keyswitch to the ON position. B. Use a multimeter in order to measure the voltage from pin A (battery+) and pin B (ground) of the diagnostic connector.	11.0 VDC and 13.5 VDC for a 12 VDC system. 22.0 VDC and 27.0 VDC for a 24 VDC system.	Result: The voltage is between 22.0 VDC and 27.0 VDC for a 24 V system. The voltage is between 11.0 VDC and 13.5 VDC for a 12 V system. The diagnostic connector is currently receiving the correct voltage. Proceed to Test Step 5. Result: The voltage is not between 22.0 VDC and 27.0 VDC for a 24 V system. The voltage is not between 11.0 VDC and 13.5 VDC for a 12 V system. The diagnostic connector is not currently receiving the correct voltage. Proceed to Test Step 4.

Illustration 5	g03705906
Typical view of the diagnostic connector from the wire side (A) Switched battery + (B) Battery ground (GND) (D) Data link + (E) Data link -

Table 3

Troubleshooting Test Steps	Values	Results
4. Bypass the Wiring for the Diagnostic Connector A. Disconnect the wires from pin A and pin B of the diagnostic connector. Note: If the diagnostic connector is mounted on the engine, perform Steps B to D. If the diagnostic connector is mounted off the engine, perform Step E. B. Disconnect the wires from P2:56 and P2:64. C. Fabricate a jumper wire in order to connect pin A of the diagnostic connector to P2:56. D. Fabricate a jumper wire in order to connect pin B of the diagnostic connector to P2:64. E. Fabricate a jumper wire in order to connect pin "A" of the diagnostic connector to battery+ and pin "B" to the battery-. F. Connect the electronic service tool to the diagnostic connector that is on the engine harness or on the application. G. Turn the keyswitch to the ON position. The power lamp should illuminate on the communications adapter.	Other devices are OK	Result: The power lamp is illuminated. The fault is in the harness. Repair: Repair the faulty harness or replace the faulty harness. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault. Result: The power lamp is not illuminated. Proceed to Test Step 6.
5. Check the Data Link Connections A. Turn the keyswitch to the OFF position. B. Disconnect the communications adapter from the diagnostic connector. C. If the diagnostic connector is installed on the application, disconnect connector P1 from the ECM. Check the resistance between P1:20 and pin "D" on the diagnostic connector. Check the resistance between P1:28 and pin "E" on the diagnostic connector. D. If the diagnostic connector is installed on the engine, disconnect P2 from the ECM. Check the resistance between P2:47 and pin "D" on the diagnostic connector. Check the resistance between P2:55 and pin "E" on the diagnostic connector.	Less than ten Ohms	Result: The resistances are less than ten Ohms. Proceed to Test Step 6. Use the electronic service tool to clear all logged diagnostic codes. Verify that the repair eliminates the fault. Result: At least one of the resistances is greater than ten Ohms. Repair: Repair the connectors and/or the harness, or replace the connectors and/or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are correctly connected. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.
6. Change the Electronic Service Tool Components A. If another electronic engine is available, connect the electronic service tool to the other engine. Ensure that the same cables are used. B. Turn the keyswitch to the ON position. Determine if the electronic service tool operates correctly on the other engine. C. If another engine is not available, obtain a replacement communications adapter and a replacement set of cables. Ensure that the cables for the electronic service tool are a complete set. D. Install the replacement communications adapter and the set of cables for the electronic service tool and connect to the diagnostic connector. E. Turn the keyswitch to the ON position. F. If changing the communications adapter or the cables allows the electronic service tool to operate correctly, perform steps G to H. G. Replace the components from the new set of cables with components from the original set of cables. Replace one component at a time. H. Apply power to the electronic service tool after each of the components is replaced. Use this method to identify the faulty component. I. If changing the cables does not allow the electronic service tool to operate correctly, connect another electronic service tool. J. Turn the keyswitch to the ON position.	Power to the comms adapter	Result: A different electronic service tool works on the original engine while the engine is being tested. Repair: Send the faulty electronic service tool for repairs. Result: The original electronic service tool works on another engine. Proceed to Test Step 7.

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Batteries give off flammable fumes which can explode. To avoid injury or death, do not strike a match, cause a spark, or smoke in the vicinity of a battery.

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NOTICE
Do not connect the bypass harness to the battery until the in-line fuse has been removed from the Battery+ line. If the fuse is not removed before connection to the battery, a spark may result.

Illustration 6	g03732687
Schematic of the bypass harness connector

Illustration 7	g03134740
Typical view of the pin locations on connector P1 for the bypass harness (20) Data link + (25) J1939 (CAN) + (26) J1939 (CAN) - (28) Data link - (69) Keyswitch (81) Battery ground (GND) (82) Battery ground (GND) (83) Battery ground (GND) (84) Battery + (85) Battery + (86) Battery +

Table 4

Troubleshooting Test Steps	Values	Results
7. Connect an Electronic Service Tool and the ECM to another Battery Note: Refer to Figure 6 for details of the bypass harness. A. Connect the battery wires from the bypass harness of the electronic service tool to a different battery that is not on the engine.	Bypass harness	Result: The electronic service tool is operating correctly. Refer to Troubleshooting, "Electrical Power Supply - Test". Result: The electronic service tool is not operating correctly. Repair: Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "ECM Software - Install". Remove all temporary jumpers and reconnect all connectors. Contact the Dealer Solutions Network (DSN).