The fuel metering valve is an electronic gas valve that controls the flow of fuel to the engine. The valve works with the ECM in order to ensure the correct flow of gas in all conditions of engine operation.
The Electronic Control Module (ECM) sends a command signal for the flow of fuel and information about the specific gravity of the gas to the fuel metering valve. The valve converts the command signal and the information into a valve position that directly corresponds to the desired gas flow. The position of the valve is compensated by these additional factors that are internal to the valve: a signal for absolute fuel pressure, differential pressure across the valve and fuel temperature sensors.
CAN Data Link
The ECM sends the following information to the fuel metering valve via the CAN data link:
- The specific gravity of the fuel
- Command signal for the fuel flow
The fuel metering valve sends the following information to the ECM via the CAN data link:
- Position of the fuel valve
- Absolute fuel pressure
- Differential pressure across the valve
- Fuel temperature
If the ECM and the fuel metering valve cannot communicate via the CAN data link, a 1446-09 diagnostic code is activated. The fuel metering valve will use the command signal from the pulse width modulated signal (PWM). The engine will continue to run. However, operation will be degraded.
PWM Signal
The ECM sends the command signal for the fuel flow via a PWM signal. If the PWM signal for the flow of fuel is interrupted, a 1446-05 diagnostic code will be activated. The fuel metering valve will use the command signal for the fuel flow via the CAN data link.
Status Indicator for the Fuel Metering Valve
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| Illustration 1 | g00996218 |
Status indicator for the fuel metering valve | |
The fuel metering valve contains a status indicator. The indicator flashes in order to indicate the status of the valve. The color of the indicator indicates the severity of the problem. During operation, the status indicator will flash one of the following colors:
Green - Normal operation
Orange - The valve has detected a problem and the valve continues to operate.
Red - The valve has detected a serious problem. The valve has shut down.
The flash code indicates the particular error that has been detected by the valve. Before performing maintenance on the valve, observe the status indicator. Refer to Installation and Operation Manual, SEBU7630 for additional information.
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| Illustration 2 | g01089854 |
Schematic for the circuit of the fuel metering valve | |
Test Step 1. Inspect the Electrical Connectors and Wiring
- Set the engine control to the OFF/RESET mode. Remove the electrical power from the engine.
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| Illustration 3 | g01089805 |
Terminal box (1) ECM connectors J1/P1 (2) J5/P5 connectors for the customer's connections (3) J8/P8 connectors for the wiring to the fuel metering valve (4) J13/P13 connectors for the termination resistor (5) J10/P10 connectors for the harness to the optional control panel | |
- Thoroughly inspect each of the following connectors:
- J1/P1 connectors
- J5/P5 and J13/P13 connectors
- J8/P8 and J10/P10 connectors on the terminal box
- Check the torque of the allen head screw for the ECM connector. The proper torque is 6 ± 1 N·m (55 ± 9 lb in).
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the fuel metering valve.
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Illustration 4 g01089809
Harness side of the P1 connector
(P1-34) CAN data link -
(P1-42) CAN shield
(P1-50) CAN data link +
(P1-58) PWM signal for the fuel flow
(P1-60) Return for the PWM signal
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Illustration 5 g01089810
Harness side of the P8 connector
(P8-D) PWM signal for the fuel flow
(P8-O) CAN data link +
(P8-Y) CAN data link -
(P8-h) CAN shield
(P8-j) Switched +Battery
(P8-u) +24 VDC for the switched +Battery
(P8-z) Return for the PWM signal
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Illustration 6 g01221974
Harness side of the P24 connector
(P24-C) CAN Data Link +
(P24-F) CAN Data Link -
(P24-K) +Battery
(P24-L) -Battery
(P24-M) Switched +Battery
(P24-P) Termination Resistor
(P24-R) Termination Resistor
(P24-S) PWM signal for the fuel flow
(P24-T) Return for the PWM signal
- Check the wiring for abrasion and for pinch points from the fuel metering valve to the ECM.
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Illustration 7 g01021995
Fuel metering valve
- J1/P1 connectors
Note: For the following steps, refer to Troubleshooting, "Inspecting Electrical Connectors".
Expected Result:
All of the connectors, pins, and sockets are connected properly. The connectors and the wiring are free of corrosion, of abrasion, and of pinch points.
Results:
- OK - The components are in good condition with proper connections. Proceed to Test Step 2.
- Not OK - The components are not in good condition and/or at least one connection is improper.
Repair: Perform the necessary repairs and/or replace parts, if necessary. Ensure that all of the seals are properly installed. Ensure that the connectors are properly engaged. Verify that the repair has eliminated the original problem.
STOP
Test Step 2. Check for Diagnostic Codes
- Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
- Restore the electrical power to the engine. Set the engine control to the STOP mode.
- Observe the "Active Diagnostic" screen of Cat ET. Wait at least 30 seconds so that any codes may become activated. Look for these codes:
- 1446-05 "Fuel Metering Module open circuit"
- 1446-09 "Unable to communicate with Fuel Metering Module"
- 1446-12 "Fuel Metering Module malfunction"
- 1446-13 "Fuel Metering Module calibration required"
- 1447-12 "Fuel Metering Sensor Module malfunction"
- 1446-05 "Fuel Metering Module open circuit"
Expected Result:
There are no active diagnostic codes.
Results:
- OK - There are no active diagnostic codes. The signal and the communication between the ECM and the fuel metering valve appear to be OK at this time. However, diagnostic codes may be logged.
Repair: If you are troubleshooting an intermittent problem, refer to Troubleshooting, "Inspecting Electrical Connectors".
STOP
- Not OK (Active 1446-05) - There may be a problem with the PWM signal between the ECM and the fuel metering valve. Proceed to Test Step 3.
- Not OK (Active 1446-09) - There may be a problem with the CAN data link between the ECM and the fuel metering valve. Proceed to Test Step 3.
- Not OK (Active 1446-12) - The fuel metering valve has detected an internal malfunction.
Repair: Refer to Installation and Operation Manual, SEBU7630.
STOP
- Not OK (Active 1446-13) - The fuel metering valve requires calibration.
Repair: Refer to Installation and Operation Manual, SEBU7630.
STOP
- Not OK (Active 1447-12) - There is a malfunction of the sensor module in the fuel metering valve.
Repair: Refer to Installation and Operation Manual, SEBU7630.
STOP
Test Step 3. Verify that the Fuel Metering Valve is Receiving Electrical Power
- Set the engine control to the OFF/RESET mode. Remove the electrical power from the engine.
- Disconnect the P24 connector.
- Set the engine control to the STOP mode. Restore the electrical power to the engine.
- Measure the voltage between terminals P24-M and P24-L. Then, measure the voltage between terminals P24-K and P24-L.
- Set the engine control to the OFF/RESET mode. Remove the electrical power from the engine.
Expected Result:
Both of the voltage measurements are approximately equal to the battery voltage.
Results:
- OK - Both of the voltage measurements are approximately equal to the battery voltage. If you are troubleshooting a 1446-05 diagnostic code, proceed to Test Step 4. If you are troubleshooting a 1446-09 diagnostic code, proceed to Test Step 5.
- Not OK - At least one of the voltage measurements is not approximately equal to the battery voltage. There is a problem with a wiring harness or a connector.
Repair: Repair the connector and/or the wire, when possible. Replace parts, if necessary. Verify that the original problem is resolved.
STOP
Test Step 4. Check the Wiring for the PWM Signal for the Fuel Flow
- Disconnect the P1 connector.
- Check for continuity between the points that are listed in Table 2. During each measurement, wiggle the wires in the harness in order to check for an intermittent problem. Be sure to wiggle the wires near each of the connectors.
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Table 1 Points to Check for Continuity Connector and Terminal Connector and Terminal P1-58 P24-S P1-63 P24-L P1-58 ECM ground strap
Expected Result:
Both of the wires have continuity. Terminal P1-58 is not shorted to ground.
Results:
- OK - All of the measurements are within the specifications. The wiring appears to be okay.
Repair: Perform the following procedure:
- Reconnect the P1 and P24 connectors.
- Start the engine and run the engine. Look for a 1446-05 diagnostic code.
If the code does not recur, the problem appears to be resolved. The original problem was probably caused by a poor electrical connection. STOP.
- If the 1446-05 code remains active, there may be a problem with the ECM or with the fuel metering valve. It is unlikely that the ECM or the fuel metering valve has failed. Exit this procedure and perform this procedure again. If the code remains active, perform the following procedure:
- Temporarily install a new ECM. Refer to Troubleshooting, "Replacing the ECM". If the problem is resolved with the new ECM, install the original ECM and verify that the problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM. Refer to Troubleshooting, "Replacing the ECM". If the problem is not resolved with a new ECM, install the original ECM. Continue with this procedure.
- Temporarily install a new fuel metering valve. If the new fuel metering valve operates correctly, the problem is resolved. If the new fuel metering valve does not operate correctly, install the original fuel metering valve. Refer to Troubleshooting, "Inspecting Electrical Connectors".
STOP
- Not OK - At least one of the measurements is incorrect. There is a problem with the wiring between the ECM and the fuel metering valve.
Repair: Repair the connector and/or the wire, when possible. Replace parts, if necessary.
STOP
Test Step 5. Check the Wiring for the CAN Data Link for Continuity
- Disconnect the P1 connector.
- Check for continuity between the points that are listed in Table 3. During each measurement, wiggle the wires in the harness in order to check for an intermittent problem. Be sure to wiggle the wires near each of the connectors.
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Table 2 Continuity Checks for the CAN Data Link Connector and Terminal Connector and Terminal P1-50 P24-C P1-34 P24-F
Expected Result:
Both of the wires have continuity.
Results:
- OK - The wiring has continuity. Proceed to Test Step 6.
- Not OK - At least one of the wires for the CAN data link is an open circuit.
Repair: Perform the necessary repairs to the wiring and/or connectors. Replace parts, if necessary. Ensure that all of the seals are properly installed. Ensure that the connectors are properly engaged. Verify that the repair has eliminated the original problem.
STOP
Test Step 6. Check the Wiring for the CAN Data Link for a Short Circuit
- Check for a short circuit between the points that are listed in Table 4. During each measurement, wiggle the wires in the harness in order to check for an intermittent problem. Be sure to wiggle the wires near each of the connectors.
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Table 3 Checks for a Short Circuit for the CAN Data Link Connector and Terminal Connector and Terminal P1-50 All of the remaining terminals on the P1 connector P1-50 ECM ground strap P1-34 All of the remaining terminals on the P1 connector P1-34 ECM ground strap
Expected Result:
All of the measurements are an open circuit.
Results:
- OK - All of the measurements are an open circuit. The wiring for the CAN data link does not have a short circuit.
Repair: Perform the following procedure:
- Reconnect the P1 and P24 connectors.
- Start the engine and run the engine. Look for a 1446-09 diagnostic code.
If the code does not recur, the problem appears to be resolved. The original problem was probably caused by a poor electrical connection. STOP.
- If the 1446-09 code remains active, there may be a problem with the ECM or with the fuel metering valve. It is unlikely that the ECM or the fuel metering valve has failed. Exit this procedure and perform this procedure again. If the code remains active, perform the following procedure:
- Temporarily install a new ECM. Refer to Troubleshooting, "Replacing the ECM". If the problem is resolved with the new ECM, install the original ECM and verify that the problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM. Refer to Troubleshooting, "Replacing the ECM". If the problem is not resolved with a new ECM, install the original ECM. Continue with this procedure.
- Temporarily install a new fuel metering valve. If the new fuel metering valve operates correctly, the problem is resolved. If the new fuel metering valve does not operate correctly, install the original fuel metering valve. Refer to Troubleshooting, "Inspecting Electrical Connectors".
STOP
- Not OK - At least one resistance measurement indicates a short circuit.
Repair: Ensure that all of the seals are properly installed. Ensure that the connectors are properly engaged. Perform the necessary repairs to the wiring and/or to the connectors. Replace parts, if necessary. Verify that the repair has eliminated the original problem.
STOP