The Electronic Control Module (ECM) has two throttle inputs and two engine synchronization inputs. The engine synchronization inputs are controlled in order to allow the ECM to respond to either of the throttle inputs. This capability allows all of the engines that are synchronized to respond to a single throttle. This minimizes variations in speed and in load between engines during engine operation.
Use this procedure in order to troubleshoot any suspect problems with engine synchronization. The following items can cause problems with engine synchronization:
- Configuration parameters
- Harness wiring or components
- ECM
The following configuration parameters affect engine synchronization:
- "Number of Synchronized Engines Configuration"
- "Engine Location"
- "Secondary Throttle Enable Status"
These parameters must be programmed correctly in order for the engines to become synchronized. Refer to Troubleshooting, "Configuration Parameters" for information that is related to programming these parameters in the correct manner.
The engine synchronization inputs operate according to the following conditions:
When neither of the engine synchronization inputs are connected to the −Battery, the ECM will respond to the signal that is present at the primary throttle input.
When the engine synchronization input (No. 1) is connected to the −Battery, the ECM will respond to the signal that is present at the primary throttle input.
When the engine synchronization input (No. 2) is connected to the −Battery, the ECM will respond to the signal that is present at the secondary throttle input.
If the engine synchronization input (No. 1) and the engine synchronization input (No. 2) are connected to the −Battery at the same time, the ECM will respond to the signal that is present at the primary throttle input. The application's wiring should be designed to prevent this condition from occurring.
Note: The ECM will not transfer control between the throttle inputs unless the throttle inputs are within 50 rpm of each other.
There are four possible configurations for engine synchronization. The following information describes each configuration.
Single Engine Configuration
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| Illustration 1 | g01376237 |
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Schematic for a single engine configuration | |
In this configuration, a single engine can be controlled by two throttles. The secondary throttle is enabled by activation of a switch. This switch is wired to the engine synchronization input (No. 2).
Dual Engine Configuration
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| Illustration 2 | g01376470 |
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Schematic for a dual engine configuration | |
In this configuration, the position of the synchronization switch determines the throttle input that is recognized by each engine. Table 1 lists the engine's response to each position of the switch.
| Engine Response to the Synchronization Switch | |
|---|---|
| Position of the Synchronization Switch | Engine Response |
| Starboard | Both engines respond to the starboard throttle. |
| None | Each engine responds to a separate throttle. |
| Port | Both engines respond to the port throttle. |
Multiple Engine Configuration Without a Dedicated Master Throttle
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| Illustration 3 | g01376549 |
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Multiple engine configuration with one throttle that is designated as a master throttle | |
In these configurations, one of the throttles has been designated as the master throttle. When the engine synchronization switch is not activated, each engine will respond to the appropriate throttle. When the engine synchronization switch is activated, all of the engines will respond to the master throttle. Three engines and three throttles are shown. As many as five engines and five throttles can be connected in this manner.
Multiple Engine Configuration With a Dedicated Master Throttle
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| Illustration 4 | g01376556 |
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Multiple engine configuration with a separate throttle that is used for the master throttle | |
In this configuration, the application is equipped with a master throttle in addition to a separate throttle for each engine. When the engine synchronization switch is not activated, each engine will respond to the appropriate throttle. When the engine synchronization switch is activated, all of the engines will respond to the master throttle.
Test Step 1. Verify that the Throttle Positions are Correct
- Determine the application's configuration for engine synchronization. Identify the two throttles that are connected to the throttle inputs for the ECM.
Note: The ECM will not transfer control between the throttles unless the throttle positions are within 50 rpm of each other.
- Verify that the throttle positions are within 50 rpm of each other.
Expected Result:
The throttle positions are within 50 rpm of each other.
Results:
- OK - The throttle positions are within 50 rpm of each other. Proceed to Test Step 2.
- Not OK - The throttle positions are not within 50 rpm of each other.
Repair: Adjust the throttles until the throttle positions are within 50 rpm of each other. Try to synchronize the engines.
If the engines become synchronized, the problem seems to be resolved at this time.
If the engines do not become synchronized, proceed to Test Step 2.
Test Step 2. Check the Configuration Parameters
- Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
- Verify that the following configuration parameters are programmed correctly:
- Number of Synchronized Engines Configuration
- Engine Location
- Secondary Throttle Enable Status
Refer to Troubleshooting, "Configuration Parameters" for additional information on these parameters.
Expected Result:
The configuration parameters are programmed correctly.
Results:
- OK - The configuration parameters are programmed correctly. Proceed to Test Step 3.
- Not OK - The configuration parameters are not programmed correctly.
Repair: Program the correct value for each parameter.
Verify that the problem is resolved.
STOP
Test Step 3. Check for Diagnostic Codes for the Throttle Inputs
- Check for the following diagnostic codes:
- 91-13 Throttle Position calibration required
- 1249-13 Secondary Throttle Position calibration required
Expected Result:
Neither diagnostic code is active or logged.
Results:
- OK - Neither diagnostic code is active or logged. Proceed to Test Step 4.
- Not OK - At least one of the diagnostic codes is logged.
Repair: Perform the following procedure:
- Clear the logged codes.
- Slowly move the suspect throttle throughout the entire range. Move the throttle several times. Look for the activation of the diagnostic code again.
If the diagnostic code does not recur, attempt to synchronize the engines. If the engines become synchronized, the problem appears to be resolved.
The original problem may have been caused by an intermittent problem in one of these components:
- Throttle position sensor
- Wiring for the throttle
- An electrical connector
If the diagnostic code recurs, there is a problem with the circuit for the throttle position sensor. Refer to Troubleshooting, "Speed Control - Test" for the troubleshooting procedure.
STOP
- Not OK - There is an active diagnostic code for a throttle.
Repair: Troubleshoot the circuit for the throttle. Refer to Troubleshooting, "Speed Control - Test" for the troubleshooting procedure.
Verify that the problem is resolved.
STOP
Test Step 4. Check the Engine Synchronization Inputs
- Turn the keyswitch to the OFF position.
- Disconnect the J1/P1 ECM connectors.
Show/hide table
Illustration 5 g01376563 Terminal locations at the P1 ECM connector that are for the engine synchronization inputs
(P1-35) Sync Input 1
(P1-44) Sync Input 2 - Perform the resistance measurements that apply to your application's configuration:
- If your application has a single engine, measure the resistance between the points that are listed in Table 2. Be sure to wiggle the wires between the switch that enables the secondary throttle and the ECM as you make each measurement.
Show/hide table
Table 2 Resistance Measurements for a Single Engine Configuration Switch Position for the Secondary Throttle Input Terminals Expected Result Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Open circuit P1-44 P1-63 Less than ten Ohms - If your application has two engines, measure the resistance between the points that are listed in Table 3. Only perform the measurements on the engine that will not become synchronized. Be sure to wiggle the wires between the Synchronization Switch and the ECM as you make each measurement.
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Table 3 Resistance Measurements for a Dual Engine Configuration Engine Position of the Engine Synchronization Switch Terminals Expected Result Port None P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Port P1-35 P1-63 Less than ten Ohms P1-44 P1-63 Open circuit Starboard P1-35 P1-63 Open circuit P1-44 P1-63 Less than ten Ohms Starboard None P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Port P1-35 P1-63 Open circuit P1-44 P1-63 Less than ten Ohms Starboard P1-35 P1-63 Less than ten Ohms P1-44 P1-63 Open circuit - If your application has two engines and one throttle that is designated as the master throttle, measure the resistance between the points that are listed in Table 4. Only perform the measurements that apply to the configuration of your application's throttle controls. Be sure to wiggle the wires between the synchronization switch and the ECM as you make each measurement.
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Table 4 Resistance Measurements for a Multiple Engine Configuration With One Throttle that is Designated as a Master Throttle Engine Master Throttle Position of the Engine Synchronization Switch Terminals Expected Result Port Port Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Less than ten Ohms P1-44 P1-63 Open circuit Center Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Open circuit P1-44 P1-63 Less than ten Ohms Starboard Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Open circuit P1-44 P1-63 Less than ten Ohms Center Port Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Open circuit P1-44 P1-63 Less than ten Ohms Center Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Less than ten Ohms P1-44 P1-63 Open circuit Starboard Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Open circuit P1-44 P1-63 Less than ten Ohms Starboard Port Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Open circuit P1-44 P1-63 Less than ten Ohms Center Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Open circuit P1-44 P1-63 Less than ten Ohms Starboard Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Less than ten Ohms P1-44 P1-63 Open circuit - If your application has two engines and a dedicated master throttle, measure the resistance between the points that are listed in Table 5. Only perform the measurements that apply to the configuration of your application's throttle controls. Be sure to wiggle the wires between the engine synchronization switch and the ECM as you make each measurement.
Show/hide table
Table 5 Resistance Measurements for a Multiple Engine Configuration With a Dedicated Master Throttle Position of the Engine Synchronization Switch Terminals Expected Result Disabled P1-35 P1-63 Open circuit P1-44 P1-63 Open circuit Enabled P1-35 P1-63 Open circuit P1-44 P1-63 Less than ten Ohms
- If your application has a single engine, measure the resistance between the points that are listed in Table 2. Be sure to wiggle the wires between the switch that enables the secondary throttle and the ECM as you make each measurement.
Expected Result:
The resistance measurements are correct.
Results:
- OK - The resistance measurements are correct.
Repair: Perform the following procedure:
- Connect the J1/P1 connectors.
- Attempt to synchronize the engines.
- If the engines will not synchronize, there may be a problem with the ECM.
It is unlikely that the ECM has failed. Exit this procedure and perform this entire procedure again. If the engines will not synchronize, replace the ECM. Refer to Troubleshooting, "ECM - Replace".
Verify that the problem is resolved.
STOP
- Not OK - At least one resistance measurement is incorrect. There is a problem with the circuit for engine synchronization. There may be a problem with an electrical connector.
Repair: Carefully inspect the wiring between the ECM and the Synchronization Switch. Refer to Troubleshooting, "Electrical Connectors - Inspect". Repair the wiring, when possible. Replace parts, if necessary. Verify that the problem is resolved.
STOP