5031798 JOHNSON SCREW (6X12)

Recommended Actions
Note: GM vehicles refer to the Check Engine Lamp as the Service Engine Soon Lamp.Perform the following diagnostic procedures in order:Intermittent Diagnostic Codes
Use Caterpillar Electronic Technician (ET) to check for any diagnostic codes that may be logged or active. Check for any intermittent diagnostic codes.Check Engine Lamp
In order to check the check engine lamp, place the ignition key switch in the ON position while the engine is off. The check engine lamp should turn on. Then, the check engine lamp should turn off. The check engine lamp will flash if there is an active diagnostic code.
Place the ignition key switch in the OFF position.
If the check engine lamp did not operate correctly remove the terminal for the check engine lamp (terminal 28) from the 70-pin connector at the Engine Control Module (ECM).
Connect the check engine lamp (terminal 28) to the ground stud. Place the ignition key switch in the ON position.
Observe the check engine lamp. If the check engine lamp comes on there may be a problem with the circuit. Place the ignition key switch in the OFF position. Check the power connection and the ground connection of the ECM. Refer to Troubleshooting, "Check Engine Lamp Circuit - Test" for additional information.If the lamp does not come on there may be a problem with the lamp. Place the ignition key switch in the OFF position. Check the lamp in order to ensure that the lamp is not burned out. Also, check the wiring in order to ensure that there is not an open circuit or a short circuit.Warning Lamp
In order to check the warning lamp, start the engine. The warning lamp should come on for at least two seconds. Then, the warning lamp should turn off. The warning lamp will remain on or flash if there is a problem with the engine.
Place the ignition key switch in the OFF position. The engine should be off.
If the warning lamp did not operate correctly remove the terminal for the warning lamp (terminal 29) from the 70-pin connector at the ECM.
Connect the warning lamp (terminal 29) to the ground stud. Place the ignition key switch in the ON position.
Observe the warning lamp. If the warning lamp comes on there may be a problem with the circuit. Place the ignition key switch in the OFF position. Check the power connection and the ground connection of the ECM. Refer to Troubleshooting, "Warning Lamp Circuit - Test" for additional information.If the lamp does not come on there may be a problem with the lamp. Place the ignition key switch in the OFF position. Check the lamp in order to ensure that the lamp is not burned out. Also, check the wiring in order to ensure that there is not an open circuit.Cruise Control Set/Resume Switch
Connect Cat ET to the cab data link connector. Place the ignition key switch in the ON position. Observe the status screen for the cruise control set/resume switch.If the status screen indicates that the switch is on and the switch is not in the ON position, the switch is shorted out. Refer to Troubleshooting, "Cruise Control Switch Circuit - Test".Short in Vehicle Harness
Check Engine Lamp
Monitor the check engine lamp while the terminal for the check engine lamp (terminal 28) is removed from the P2 ECM connector. Also, the technician could monitor the check engine lamp while the ECM connector is disconnected.If the lamp remains on and the terminal has been removed from the ECM, there is a short circuit to ground in the vehicle harness.Warning Lamp
Monitor the warning lamp while the terminal for the warning lamp (terminal 29) is removed from the P2 ECM connector. Also, the technician could monitor the warning lamp while the ECM connector is disconnected.If the lamp remains on and the terminal has been removed from the ECM there is a short circuit to ground in the vehicle harness.Service Engine Soon Lamp (GM)
Check the ALDL connector in order to ensure that there is not a short circuit between terminal 4 and terminal 6. Also, check for a short between terminal 5 and terminal 6.
Illustration 1 g01113297
GM ALDL cab connector.
(4) -Battery
(5) -Battery
(6) Diagnostic enable
(7) J1587 Data Link +
(15) J1587 Data Link -
(16) +Battery