Verify that there are no problems with the starting system or the charging system before you use this test.
Use this procedure to troubleshoot the electrical system if a problem is suspected with the power to the Electronic Control Module (ECM) or if any one of the diagnostic codes in Table 1 is active or easily repeated.
| Diagnostic Codes Table | ||
|---|---|---|
| Code and Description | Conditions which Generate this Code | System Response |
| 168-0 Electrical System Voltage high - most severe (3) | The battery supply voltage is greater than 32 VDC on 24 VDC systems for 0.5 seconds, or the battery supply voltage is greater than 16 VDC on 12 VDC systems for 0.5 seconds.
The engine's ECM has been powered for three seconds. The engine has been running for at least 30 seconds. |
The code is logged. |
| 168-1 Electrical System Voltage low - most severe (3) | The battery supply voltage is less than 18 VDC on 24 VDC systems for 0.5 seconds or the battery supply voltage is less than 9 VDC on 12 VDC systems for 0.5 seconds.
The engine's ECM has been powered for three seconds. The engine is running for at least 3 seconds. |
|
| 168-2 Electrical System Voltage erratic, intermittent, or incorrect | The battery voltage falls below 6 VDC and the voltage returns above 9 VDC for three voltage readings in the last seven seconds.
The engine is running. |
|
The +Battery voltage to the Electronic Control Module is controlled via a relay. The emergency stop switch controls this relay. The emergency stop switch is located on the panel for the Electronic Modular Control Panel (EMCP). When the switch is in the engine run position the relay is energized. The energized relay provides power to the ECM. The following four terminals at the J1 ECM connector are powered simultaneously:
- P1-48 +Battery
- P1-52 +Battery
- P1-53 +Battery
- P1-70 Keyswitch
When the ECM detects battery voltage at P1-70 keyswitch , the ECM will power up. When battery voltage is lost from this input, the ECM will power down.
The −Battery is supplied to the ECM through a battery disconnect switch that is used to manually remove the battery power from all electrical components.
| |
| Illustration 1 | g01414053 |
|
Schematic for the electrical power supply circuit | |
Test Step 1. Inspect the Electrical Connectors and the Wiring
- Remove electrical power from the engine ECM.
- Thoroughly inspect connectors (1) and (2). Inspect all of the connectors that are in the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
Show/hide table
Illustration 2 g01341802 Terminal locations at the P1 ECM connectors for the electrical power supply circuit
(P1-48) +Battery
(P1-52) +Battery
(P1-53) +Battery
(P1-61) −Battery
(P1-63) −Battery
(P1-65) −Battery
(P1-70) Keyswitch - Perform a
45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit. - Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
- Check the harness and the wiring for abrasion and for pinch points.
Expected Result:
All connectors, pins, and sockets are completely inserted and coupled. The harness and wiring are free of corrosion, of abrasion, and of pinch points. All connections are tight and free of corrosion.
Results:
- OK - The harness and wiring appear to be OK. Proceed to Test Step 2.
- Not OK - There is a problem in the connectors and/or wiring.
Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled. Verify that the repair eliminates the problem.
STOP
Test Step 2. Check the Battery Voltage at the ECM
- Remove electrical power from the ECM.
- Disconnect the J1/P1 ECM connector.
- Restore electrical power to the ECM.
- Wiggle the wires in the harness while performing the following test steps.
- Measure the voltage between P1-48 (+Battery) and P1-61 (−Battery).
- Measure the voltage between P1-52 (+Battery) and P1-63 (−Battery).
- Measure the voltage between P1-53 (unswitched +Battery) and P1-65 (−Battery).
- Measure the voltage between P1-70 (keyswitch) and P1-63 (−Battery).
Expected Result:
The measured voltage is between 9 VDC and 15 VDC for 12 volt systems. The measured voltage is between 22 VDC and 27 VDC for 24 volt systems.
Results:
- OK - The ECM is receiving the correct voltage.
Repair: There may be an intermittent electrical problem in a harness or in a connector. If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect".
STOP
- Battery voltage out of range - The voltage is not correct for one of the battery circuits at the ECM. Proceed to Test Step 3.
Test Step 3. Check the Batteries
- Measure the no-load battery voltage at the battery posts.
- Load test the batteries. Use the 4C-4911 Battery Load Tester. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6, 8 and 12 Volt Lead Acid Batteries" and Special Instruction, SEHS7633, "Battery Test Procedure".
Expected Result:
The batteries pass the load test.
Results:
- OK - The batteries pass the load test.
Repair: The batteries are OK. There is an open circuit or excessive resistance in the wiring or connections between the batteries and the ECM. Verify that the 15 Amp circuit breaker for the ECM is not tripped. Verify that the connections at the bus bars that are for the battery are clean and tight. Repair the connectors or wiring and/or replace the connectors or wiring between the battery and the J1/P1 ECM connector.
STOP
- Not OK - The battery voltage is low or the battery did not pass the load test.
Repair: Recharge or replace the faulty batteries. Verify that the repair eliminates the problem.
STOP