0391716 JOHNSON CARB ASSY., Upper, 140

Table 1
Diagnostic Codes Table
Code and Description Conditions which Generate this Code System Response
1-5 Cylinder #1 Injector current below normal The Electronic Control Module (ECM) detects an open circuit. The code is logged.
The ECM continues to fire the injector solenoid.
1-6 Cylinder #1 Injector current above normal The ECM detects a short circuit. The code is logged.
The ECM will disable the solenoid circuit. The ECM will periodically try to fire the injector. If the short circuit remains, this sequence of events will be repeated until the problem is corrected.
2-5 Cylinder #2 Injector current below normal The ECM detects an open circuit. The code is logged.
The ECM continues to fire the injector solenoid.
2-6 Cylinder #2 Injector current above normal The ECM detects a short circuit. The code is logged.
The ECM will disable the solenoid circuit. The ECM will periodically try to fire the injector. If the short circuit remains, this sequence of events will be repeated until the problem is corrected.
3-5 Cylinder #3 Injector current below normal The ECM detects an open circuit. The code is logged.
The ECM continues to fire the injector solenoid.
3-6 Cylinder #3 Injector current above normal The ECM detects a short circuit. The code is logged.
The ECM will disable the solenoid circuit. The ECM will periodically try to fire the injector. If the short circuit remains, this sequence of events will be repeated until the problem is corrected.
4-5 Cylinder #4 Injector current below normal The ECM detects an open circuit. The code is logged.
The ECM continues to fire the injector solenoid.
4-6 Cylinder #4 Injector current above normal The ECM detects a short circuit. The code is logged.
The ECM will disable the solenoid circuit. The ECM will periodically try to fire the injector. If the short circuit remains, this sequence of events will be repeated until the problem is corrected.
5-5 Cylinder #5 Injector current below normal The ECM detects an open circuit. The code is logged.
The ECM continues to fire the injector solenoid.
5-6 Cylinder #5 Injector current above normal The ECM detects a short circuit. The code is logged.
The ECM will disable the solenoid circuit. The ECM will periodically try to fire the injector. If the short circuit remains, this sequence of events will be repeated until the problem is corrected.
6-5 Cylinder #6 Injector current below normal The ECM detects an open circuit. The code is logged.
The ECM continues to fire the injector solenoid.
6-6 Cylinder #6 Injector current above normal The ECM detects a short circuit. The code is logged.
The ECM will disable the solenoid circuit. The ECM will periodically try to fire the injector. If the short circuit remains, this sequence of events will be repeated until the problem is corrected. Perform this procedure under conditions that are identical to the conditions that exist when the problem occurs. Typically, problems with the injector solenoid occur when the engine is warmed up and/or when the engine is under vibration (heavy loads).These engines have Hydraulic Electronic Unit Injectors (HEUI) that are hydraulically actuated and electronically controlled. The ECM sends a 105 volt pulse to each injector solenoid. The pulse is sent at the proper time and at the correct duration for a given engine load and speed. The solenoid is mounted on top of the fuel injector body.If an open is detected in the solenoid circuit, a diagnostic code is generated. The ECM continues to try to fire the injector. If a short is detected, a diagnostic code is generated. The ECM will disable the solenoid circuit. The ECM will periodically try to fire the injector. If the short circuit remains, this sequence of events will be repeated until the problem is corrected. When an injector is replaced, program the new injector code into the ECM. If the ECM is replaced, all six injector codes must be programmed into the new ECM. Refer to programming parameters Troubleshooting, "Injector Trim File" for more information.The Caterpillar Electronic Technician (ET) includes the following tests that aid in troubleshooting the injector solenoids:"Cylinder Cutout Test"All active diagnostic codes must be repaired before running the "Cylinder Cutout Test". Use the "Cylinder Cutout Test" to diagnose a malfunctioning injector while the engine is running. When a good injector is cut out, the "Fuel Position" should change. The change in the fuel position is caused by the other injectors that are compensating for the cut out injector. If a malfunctioning injector is cut out, the "Fuel Position" will not change. The "Cylinder Cutout Test" is used to isolate the malfunctioning injector in order to avoid replacement of good injectors."Injector Solenoid Test"Use the "Injector Solenoid Test" to aid in diagnosing an open circuit or a short circuit while the engine is not running. The "Injector Solenoid Test" briefly activates each solenoid. A good solenoid will create an audible click when the solenoid is activated. Cat ET will indicate the status of the solenoid as "OK", "Open", or "Short".Note: Refer to Illustration 1. Two injector solenoids share a common supply wire. For this reason, an open circuit or a short circuit in a supply wire could cause diagnostic codes for two injector solenoids.
Illustration 1 g01339062
Schematic for the injector solenoids
The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.
Test Step 1. Inspect the Electrical Connectors and the Wiring
Electrical shock hazard. The electronic unit injector system uses 90-120 volts.
Remove the electrical power from the ECM.
Illustration 2 g01388303
Left side engine view (typical example)
(1) Valve cover connector for the injector solenoids
(2) J2/P2 ECM connector
Thoroughly inspect connectors (1) and (2). Refer to the diagnostic functional test Troubleshooting, "Electrical Connectors - Inspect".
Illustration 3 g01339367
Terminal locations at the P2 ECM connector
(P2-99) Injector 5 & 6 supply
(P2-104) Injector 1 & 2 supply
(P2-105) Injector 6 return
(P2-106) Injector 3 return
(P2-107) Injector 5 return
(P2-108) Injector 4 return
(P2-115) Injector 3 & 4 supply
(P2-116) Injector 1 return
(P2-118) Injector 2 return