| Related Service Manuals | |
| Title | Form Number |
| D7E Track-Type Tractor Service Manual | KENR5600 |
| D7E Track-Type Tractor Electrical and Hydraulic Power Train Systems | KENR5604 |
| Monitoring System | KENR8246 |
| C9 Engine Troubleshooting | RENR5066 |
| All Products Air Conditioning and Heating R-134a for All Caterpillar Machines | SENR5664 |
| D7E Track-Type Tractor OMM | SEBU8589 |
| Additional References | |
| Electrical System Schematic | KENR5613 |
| Hydraulic System Schematic | KENR5608 |
| Cooling System Schematic | KENR5610 |
As a reference, a simplified system schematic is included at the end of this manual. For an accurate representation of the machine that is being diagnosed, refer to the Electrical System Schematic in the Service Manual of the machine. During troubleshooting, inspect all harness connections before any component is replaced. If these connections are not clean and tight, permanent electrical problems or intermittent electrical problems can result. Check that the wires are pushed into the connectors completely. Make sure that the connections are tight before other tests are made. Failure of an electrical component may cause the failure of other components. Always attempt to correct the cause of an electrical system failure before you replace a component. If wire insulation is punctured during troubleshooting, repair the damage. Seal the damaged wires with 8T-0065 RTV Silicone Sealant . Cover the sealant with two layers of 1P-0810 Electrical Tape .
Electrical System Troubleshooting
Simplified electrical system connection schematics for the Machine are included in this manual. The schematics illustrate the end connections for the control modules and the circuits for the components. The schematics do not illustrate the connectors for the machine harness.
Use the schematic of the electrical system that is located in the service manual when troubleshooting any part of the electrical system in this machine. The schematic in the Service Manual will illustrate the complete information for the circuits on the machine.
Basic Troubleshooting Practice
Poor connections can often be the cause of a problem in an electrical circuit. When a problem is suspected to exist in a particular circuit, examine the machine wiring harness connectors that are used in the circuit. Verify that each of the connection points in the circuit are clean, dry and in good condition. If the connections are not in good condition, permanent electrical problems or intermittent electrical problems can result. Check that the wires are securely terminated in the pin or socket. Ensure that the pin or socket is seated correctly and locked in the connector body. Ensure that all of the connections in the suspect circuit are in good condition before other tests are performed.
When a troubleshooting procedure instructs you to "REPAIR THE HARNESS OR REPLACE THE HARNESS", use the Electrical Schematic to investigate a circuit. Perform resistance checks between the harness connectors in a circuit in order to locate harness failures. Always check the ground circuit at the machine harness connector for the components.
For machine ground circuits, less than 5 ohms of resistance is required between the ground contacts of a connector and the frame ground. Excessive ground resistance that is greater than 5 ohms can cause an incorrect diagnosis of the system.
For ECM return circuits (ECM ground), resistance checks should be made between the circuit connections and the ECM harness connector return contact. Resistance checks that are made between the ECM return circuits and frame ground may register more than 5 ohms of resistance due to internal impedance in the ECM circuits.
When checking the continuity of an individual circuit, a resistance measurement of more than 5000 ohms will indicate an open in a conductor or an open in a connector. When a resistance measurement to check continuity in a circuit measures more than 5 ohms and less than 5000 ohms, can be an indication that a connection point that is not completely open. The circuit may contain a connection that is corroded or loose.
When checking an individual circuit for a short circuit to another circuit or to a ground source (frame ground or a ground circuit), the circuit that is being checked must be disconnected from all of the other components and circuits. Disconnect the suspect circuit that is to be checked from the control module, the component, and any other switches or sensors that may be used in the circuit.
A resistance reading of at least 5000 ohms is the suggested limit for determining if a circuit is shorted to another circuit or ground source. A resistance measurement of less than 5000 ohms can indicate that there is a "leakage" of voltage or current between the two circuits that are being measured when in operation. In some instances, a resistance measurement of less than 5000 ohms may not always indicate a short circuit. The technician should use basic troubleshooting knowledge and experience when determining if two circuits are shorted to each other or if a circuit is shorted to ground.
When the troubleshooting procedure instructs you to "REPAIR OR REPLACE THE HARNESS", use the applicable Electrical Schematic to trace the circuit. Perform continuity checks at the harness connectors in order to locate harness failures. At the connectors of the components, always check the ground circuit. Less than 5 ohms of resistance is required between the ground contacts of the connector and the frame ground. The power circuits of the ECM should have less than 2 ohms of resistance between the contacts of the ground connector and the frame ground. Less than 5 ohms of resistance is required for signal circuits for normal operation. Excessive ground resistance that is greater than 5 ohms can cause incorrect diagnosing of problems.