Use this procedure in order to troubleshoot the Engine Control Switch (ECS) or use this procedure if the diagnostic code in Table 1 is active or easily repeated.
Diagnostic Codes Table | ||
---|---|---|
Description | Conditions which Generate this Code | System Response |
336-2 Engine Control Switch erratic, intermittent, or incorrect | The two inputs from the ECS are in the opposite state. | The code is logged. |
The ECS can operate in four modes: OFF/RESET, START, STOP and REMOTE.
The engine's Electronic Control Module (ECM) receives three signals that allow the ECM to determine the mode of operation. The input signals on P1-21 and P1-22 tell the ECM the position of the ECS. The input signals on P1-21 and P1-22 must be at the same potential or a diagnostic code will be generated. The third input signal on P1-68 tells the ECM if the ECS is in the REMOTE position. If the input signal on P1-68 is low, the ECM knows that the ECS is in the REMOTE position. The ECM knows that the engine is controlled remotely by the customer. If the input signal on P1-68 is not low, the ECM knows that the ECS is not in the REMOTE position. The ECM knows that the engine is controlled locally by the ECS on the instrument panel.
When the ECS is in the REMOTE position, inputs from the customer control the operation of the engine. The following list contains some of the inputs from the customer connector and the inputs function.
- c keyswitch
- S remote input
- C remote start 2
- D remote start 1
- E remote stop 1
- F remote stop 2
When the ECS is in the REMOTE position, the "Remote Start" relay and the "Remote Stop" relay are energized. When the remote start inputs C and D go low, the following relays energize: "Run 1" relay, "Run 2" relay, "Reset 1" relay and "Reset 2" relay. The start/run/stop inputs P1-21 and P1-22 will be pulled low. The engine will begin the start cycle. When the customer's remote stop inputs F and E are low, the following relays energize: "Stop 1" relay and "Stop 2" relay. The start/run/stop inputs P1-21 and P1-22 will be high. The engine will begin the stop function. When the ECS is in the REMOTE position, the "ECS in Remote" relay energizes. The "ECS in Remote" relay sends a signal to the customer connector that allows the customer to determine the position of the ECS.
When the ECS is in the START position, the following relays energize: "Run 1" relay, "Run 2" relay, "Reset 1" relay and "Reset 2" relay. The start/run/stop inputs P1-21 and P1-22 will be pulled low. The engine will begin the start cycle.
When the ECS is in the STOP position, the following relays energize: "Stop 1" relay and "Stop 2" relay. The start/run/stop inputs P1-21 and P1-22 will be high. The engine will begin the stop function.
When the ECS is in the OFF/RESET position, the input for the keyswitch P1-70 is not pulled up to +Battery voltage and the ECM will not operate.
Illustration 1 | g01186000 |
Typical example |
Illustration 2 | g01244072 |
P1 ECM connector (P1-5) Digital return (P1-21) "Start/Run/Stop 1" (P1-22) "Start/Run/Stop 2" (P1-68) "ECS Remote/Auto" (P1-70) Keyswitch |
Illustration 3 | g01244073 |
P2 ECM connector (P2-54) Digital return (P2-55) Digital return |
Illustration 4 | g01234146 |
Location of ECM connectors |
Test Step 1. Inspect Electrical Connectors and Wiring
- Turn the circuit breaker for the battery to the OFF position.
- Turn the ECS to the OFF/RESET position.
- Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.
- 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 on each ECM connector for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" 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 coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.
Results:
- OK - The connectors and wiring are OK. Proceed to Test Step 2.
- Not OK - The connectors and/or wiring need repair.
Repair: Repair the connectors or wiring and/or replace the connectors or wiring.
STOP
Test Step 2. Check the Status of the ECS in the STOP Position
- Turn the circuit breaker for the battery to the ON position.
- Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
- Turn the ECS on the instrument panel to the STOP position.
- Observe the status for the ECS on Cat ET.
Expected Result:
The status for the ECS is "STOP".
Results:
- OK - The ECS is functioning correctly. Proceed to Test Step 3.
- Not OK - The status for the ECS is not "STOP". Proceed to Test Step 5.
Test Step 3. Check the Status of the ECS in the START Position
- Turn the ECS on the instrument panel to the START position.
- Observe the status for the ECS on Cat ET.
Expected Result:
The status for the ECS is "RUN".
Results:
- OK - The ECS is functioning correctly. Proceed to Test Step 4.
- Not OK - The status of the ECS is not "RUN". Proceed to Test Step 5.
Test Step 4. Check the Status of the ECS in the REMOTE Position
- Turn the ECS on the instrument panel to the REMOTE position.
- Observe the status for the ECS on Cat ET.
Expected Result:
The status for the ECS is "AUTO".
Results:
- OK - The ECS is working correctly.
Repair: The problem may be intermittent. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".
STOP
- ECS Not OK - The status for the ECS is not "AUTO". Proceed to Test Step 6.
Test Step 5. Install a Wire Jumper at the ECM in order to Simulate a START/STOP Function
- Turn the ECS to the OFF/RESET position.
- Disconnect the ECM connector J1/P1.
- Remove wire F716-BK(Black) from P1-21. Install a wire jumper into the socket P1-21.
- Remove wire F717-BK(Black) from P1-22. Install a wire jumper into the socket P1-22.
- Reconnect the ECM connector J1/P1.
- Fabricate a wire jumper.
- Install the wire jumper between terminal 11 of the ECS and the wire jumpers in P1-21 and P1-22.
- Turn the ECS to the STOP position.
- Observe the status for the ECS on Cat ET.
- Remove the wire jumper between terminal 11 of the ECS and the wire jumpers in P1-21 and P1-22.
- Observe the status for the ECS on Cat ET.
- Turn the ECS to the OFF/RESET position. Remove the wire jumpers and replace all wires. Reconnect the ECM connector P1.
Expected Result:
The status for the ECS displays "RUN" while the wire jumper is installed. The status for the ECS displays "STOP" when the wire jumper is removed.
Results:
- OK - The status for the ECS displays the proper states. The problem is not with the ECM. Troubleshoot the wire F716-BK(Black) and the wire F717-BK(Black). In order to troubleshoot the wire F716-BK(Black), proceed to Test Step 7. In order to troubleshoot the wire F717-BK(Black), proceed to Test Step 12.
- Not OK - The status for the ECS does not display the correct state.
Repair: Replace the ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".
STOP
Test Step 6. Install a Wire Jumper at the ECM in order to Simulate an AUTO Condition
- Turn the ECS on the instrument panel to the OFF/RESET position.
- Disconnect the ECM connector P1.
- Remove wire F721-BK(Black) from P1-68. Install a wire jumper into the socket P1-68.
- Reconnect the ECM connector P1.
- Fabricate a wire jumper.
- Install the wire jumper between terminal 11 of the ECS and the wire jumper in P1-68.
- Turn the ECS to the STOP position.
- Observe the status for the ECS on Cat ET.
- Remove the wire jumper between terminal 11 of the ECS and the wire jumper in P1-68.
- Observe the status for the ECS on Cat ET.
- Turn the ECS to the OFF/RESET position. Remove the wire jumpers and replace all wires. Reconnect the ECM connector P1.
Expected Result:
The status for the ECS displays "AUTO" while the wire jumper is installed. The status for the ECS displays "OFF" when the wire jumper is removed.
Results:
- OK - The status for the ECS displays the proper states. The problem is not with the ECM. Troubleshoot the wire F716-BK(Black) and the wire F717-BK(Black). In order to troubleshoot the wire F716-BK(Black), proceed to Test Step 7. In order to troubleshoot the wire F717-BK(Black), proceed to Test Step 12.
- Not OK - The status for the ECS does not display the correct state.
Repair: Replace the ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".
STOP
Test Step 7. Check for Voltage at the Normally Closed Contacts of the "Stop 1" Relay
- Turn the remote start switch to the OFF/RESET position.
- Turn the ECS on the instrument panel to the STOP position.
- Measure the voltage between wire F716-BK(Black) at the normally closed contacts of the "Stop 1" relay and engine ground.
Expected Result:
The voltage is 6.5 ± 0.5 VDC.
Results:
- OK - The voltage is 6.5 ± 0.5 VDC. Proceed to Test Step 13.
- Not OK - The voltage is not 6.5 ± 0.5 VDC.
Repair: Repair the wire F716-BK(Black) between terminal 22 of the "Stop 1" relay and the ECM. Test for proper operation.
STOP
Test Step 8. Check for Voltage at the "Stop 1" Relay
- Disconnect wire LR775-BK(Black) from terminal 22 of "Remote Start Enable" relay in order to isolate the circuit for testing. Insulate the removed wire end from electrical contact.
- Turn the ECS that is on the instrument panel to the STOP position.
- Measure the voltage between wire DM775-BK(Black) at terminal 21 of the "Stop 1" relay and engine ground.
Expected Result:
The voltage is +Battery.
Results:
- OK - The voltage is +Battery. Proceed to Test Step 14.
- Not OK - The voltage is not +Battery.
Repair: There is a problem with the wire DM775-BK(Black) between terminal 21 of the "Stop 1" relay and terminal A2 of the "Stop 1" relay. Repair the wire DM775-BK(Black). Reconnect wire LR775-BK(Black) to terminal 22 of the "Remote Start Enable" relay. Test for proper operation.
STOP
Test Step 9. Check for Voltage at the "REMOTE START ENABLE" Relay
- Turn the ECS that is on the instrument panel to the STOP position.
- Measure the voltage between wire PR775-BK(Black) at terminal 11 of the "Remote Start Enable" relay and engine ground.
Expected Result:
The voltage is +Battery.
Results:
- OK - The voltage is +Battery. Proceed to Test Step 15.
- Not OK - The voltage is not +Battery.
Repair: There is a problem with the wire PR775-BK(Black) between terminal 11 of the "Remote Start Enable" relay and terminal A2 of the "Run 1" relay. Repair the wire PR775-BK(Black).
Reconnect wire LR775-BK(Black) to terminal 22 of the "Remote Start Enable" relay. Test for proper operation.
STOP
Test Step 10. Check for Voltage at the ECS
- Turn the ECS that is on the instrument panel to the STOP position.
- Measure the voltage between wire LR775-BK(Black) at terminal 09 of the ECS and engine ground.
Expected Result:
The voltage is +Battery.
Results:
- OK - The voltage is +Battery. Proceed to Test Step 16.
- Not OK - The voltage is not +Battery.
Repair: There is a problem with the wire LR775-BK(Black) between terminal 09 of the ECS and terminal 12 of the "Remote Start Enable" relay or the "Remote Start Enable" relay has failed. Repair the wire LR775-BK(Black) or replace the "Remote Start Enable"relay.
Reconnect wire LR775-BK(Black) to terminal 22 of the "Remote Start Enable " relay. Test for proper operation.
STOP
Test Step 11. Check for Voltage Across the ECS
- Turn the ECS on the instrument panel to the START position.
- Measure the voltage between wire LR775-BK(Black) at terminal 09 of the ECS and digital return at terminal 06 of the ECS.
Expected Result:
The voltage is −Battery.
Results:
- OK - The voltage is −Battery.
Repair: The problem may be intermittent. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".
STOP
- Not OK - The voltage is not −Battery.
Repair: There is a problem with the digital return wire C998-BK(Black) between terminal 06 of the ECS and terminal P2-54 of the ECM or the ECS has failed. Repair the wire C998-BK(Black) or replace the ECS.
Reconnect wire LR775-BK(Black) to terminal 22 of the "Remote Start Enable " relay. Test for proper operation.
STOP
Test Step 12. Check for Voltage on Wire F717-BK(Black) at the Normally Closed Contacts of the "Stop 2" Relay
- Turn the remote start switch to the OFF/RESET position.
- Turn the ECS on the instrument panel to the STOP position.
- Measure the voltage between wire F717-BK(Black) at the normally closed contacts of the "Stop 2" relay and engine ground.
Expected Result:
The voltage is 6.5 ± 0.5 VDC.
Results:
- OK - The voltage is 6.5 ± 0.5 VDC. Proceed to Test Step 13.
- Not OK - The voltage is not 6.5 ± 0.5 VDC.
Repair: Repair the wire F717-BK(Black) between terminal 22 of the "Stop 2" relay and the ECM. Test for proper operation.
STOP
Test Step 13. Check for Voltage on Wire DM776-BK(Black) at the Normally Closed Contacts of the "Stop 2" Relay
- Disconnect wire LR775-BK(Black) from terminal 12 of "Remote Start Enable" relay in order to isolate the circuit for testing. Insulate the removed wire end from electrical contact.
- Turn the ECS that is on the instrument panel to the STOP position.
- Measure the voltage between wire DM776-BK(Black) at terminal 21 of the "Stop 2" relay and engine ground.
Expected Result:
The voltage is +Battery.
Results:
- OK - The voltage is +Battery. Proceed to Test Step 14.
- Not OK - The voltage is not +Battery.
Repair: There is a problem with the wire DM776-BK(Black) between terminal 21 of the "Stop 2" relay and terminal A2 of the "Run 2" relay. Repair the wire DM776-BK(Black). Reconnect wire LR775-BK(Black) to terminal 12 of the "Remote Start Enable" relay. Test for proper operation.
STOP
Test Step 14. Check for Voltage at the "REMOTE START ENABLE" Relay
- Turn the ECS that is on the instrument panel to the STOP position.
- Measure the voltage between wire PR776-BK(Black) at terminal 21 of the "Remote Start Enable" relay and engine ground.
Expected Result:
The voltage is +Battery.
Results:
- OK - The voltage is +Battery. Proceed to Test Step 15.
- Not OK - The voltage is not +Battery.
Repair: There is a problem with the wire PR776-BK(Black) between terminal 21 of the "Remote Start Enable" relay and terminal A2 of the "Run 2" relay. Repair the wire PR776-BK(Black).
Reconnect wire LR775-BK(Black) to terminal 12 of the "Remote Start Enable" relay. Test for proper operation.
STOP
Test Step 15. Check for Voltage at the ECS
- Turn the ECS that is on the instrument panel to the STOP position.
- Measure the voltage between wire LR775-BK(Black) at terminal 09 of the ECS and engine ground.
Expected Result:
The voltage is +Battery.
Results:
- OK - The voltage is +Battery. Proceed to Test Step 16.
- Not OK - The voltage is not +Battery.
Repair: There is a problem with the wire LR775-BK(Black) between terminal 09 of the ECS and terminal 22 of the "Remote Start Enable" relay or the "Remote Start Enable" relay has failed. Repair the wire LR775-BK(Black) or replace the"Remote Start Enable"relay.
Reconnect wire LR775-BK(Black) to terminal 12 of the "Remote Start Enable " relay. Test for proper operation.
STOP
Test Step 16. Check for Voltage Across the ECS
- Turn the ECS on the instrument panel to the START position.
- Measure the voltage between wire LR775-BK(Black) at terminal 09 of the ECS and digital return at terminal 06 of the ECS.
Expected Result:
The voltage is −Battery.
Results:
- OK - The voltage is −Battery.
Repair: The problem may be intermittent. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".
STOP
- Not OK - The voltage is not −Battery.
Repair: There is a problem with the digital return wire C998-BK(Black) between terminal 06 of the ECS and terminal P2-54 of the ECM or the ECS has failed. Repair the wire C998-BK(Black) or replace the ECS.
Reconnect wire LR775-BK(Black) to terminal 12 of the "Remote Start Enable " relay. Test for proper operation.
STOP