16915 Mercury LOCK ARM

Probable Causes
Check for Diagnostic codes and event codes
Slow cranking speed
Battery condition
Keyswitch power to the Electronic Control Module (ECM) and the Fuel Control Valve
ECM supply voltage
Engine speed/timing signal
Low-pressure fuel system
High-pressure fuel system
Fuel quality
Starting aids
Gear train problemRecommended Actions
Table 1
Troubleshooting Test Steps Values Results
1. Check for Diagnostic Codes and Event Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector. Check for active diagnostic codes and event codes.
B. Look for active diagnostic codes or active event codes that are related to the following items:
- Low-pressure fuel system
- High-pressure fuel system
- Engine speed/timing sensors
- Shutdown devices
C. Check for event codes that are logged repeatedly. Repeated codes may be evidence of an impending problem. Check for logged events that have a severity of level 3.
D. Use Cat ET to confirm the status of any shutdown devices that are installed on the application. If the application has any shutoff devices that are latched mechanically, ensure that the devices have been reset. Also, check the status of any aftermarket shutdown devices that may be installed on the application.
Codes
Result: No codes are active or logged.
Proceed to Test Step 2.
Result: Codes are active or logged. One or more codes are related to the high-pressure fuel system, the low-pressure fuel system, the engine speed/timing circuit, and shutdown devices.
Repair: Use the appropriate circuit test to troubleshoot any active diagnostic codes.
Proceed to Test Step 2.
Result: If engine starting is being prevented by one of these devices, refer to the OEM information for details.
If the problem is not resolved, proceed to Test Step 2.
2. Check for Slow Cranking Speed
A. Check the air inlet system for restrictions and/or for leaks.
B. Use Cat ET to check the engine speed while you crank the engine. If the engine cranks too slowly, the engine will not start.
C. Check for the following problems:
- Low voltage for an electric starting system
- Low air pressure for an air start system
- Excess parasitic load
- Engagement of a single starting motor on a dual starting motor system
Speed
Result: The engine speed is greater than 100 rpm for a duration of four revolutions.
Proceed to Test Step 3.
Result: The engine speed is not greater than 100 rpm for a duration of four revolutions.
Proceed to Test Step 3.
Repair: Or replace all that is necessary.
If the problem is not resolved, proceed to Test Step 3.
3. Check the Battery Condition
A. Check the charge on the engine batteries.
B. Load-test the batteries. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6 V, 8 V, and 12 V Lead Acid Batteries".
6 V, 8 V, and 12 V
Result: The batteries are charged.
Proceed to Test Step 4.
Result: The batteries are not charged.
Repair: Charge the batteries, if necessary. Refer to Special Instruction, SEHS7633, "Battery Test Procedure".
Proceed to Test Step 4.
Result: The batteries are OK.
Proceed to Test Step 4.
Result: The batteries are NOT OK.
Repair: Repair or replace the battery.
If the problem is not resolved, proceed to Test Step 4.
4. Check the Keyswitch Power to the Electronic Control Module and the Fuel Control Valve
A. Use a 7X-1708 Multimeter Probe (RED) and a 7X-1709 Multimeter Probe (BLACK). Check the voltage between terminal P1-69 (−Battery) and terminal (70) (keyswitch) at the ECM connector.
B. Crank the engine. Use a multimeter to measure the keyswitch power at the ECM while the engine is cranked.
C. Remove the multimeter probes from the engine.
D. Use the multimeter probes to check the voltage between terminals 8 and 5 of and then between terminals 1 and 5.
E. Crank the engine. Use a multimeter to measure the keyswitch power at the fuel control valve while the engine is cranked.
F. Remove the multimeter probes from the engine.
18 V
Result: The keyswitch power is greater than 18 VDC.
Proceed to Test Step 5.
Result: The keyswitch power is below 18 VDC.
Repair: Troubleshoot the problem. Refer to Troubleshooting, "Electrical Power Supply - Test" for details that are related to troubleshooting a low voltage at the keyswitch circuit.
If the problem is not resolved, proceed to Test Step 5.
5. ECM Supply Voltage
A. Install a 7X-1708 Multimeter Probe (RED) and a 7X-1709 Multimeter Probe (BLACK) onto the test leads of a multimeter.
B. Check the battery supply voltage at the ECM during engine cranking.
- Check the voltage between terminal locations P1-48 (+Battery) and P1-61 (−Battery) while you crank the engine.
- Check the voltage between terminal locations P1-52 (+Battery) and P1-61 (−Battery) while you crank the engine.
- Check the voltage between terminal locations P1-53 (+Battery) and P1-61 (−Battery) while you crank the engine.
- Check the voltage between terminal locations P1-55 (+Battery) and P1-61 (−Battery) while you crank the engine.
- Check the voltage between terminal locations P1-57 (+Battery) and P1-61 (−Battery) while you crank the engine.
C. Remove the multimeter probes from the engine.
18 V
Result: The supply voltage is greater than 18 VDC.
Proceed to Test Step 6.
Result: The supply voltage is not greater than 18 VDC.
Repair: Troubleshoot the problem. Refer to Troubleshooting, "Electrical Power Supply - Test" for details that are related to troubleshooting a low voltage at the keyswitch circuit.
If the problem is not resolved, proceed to Test Step 6.
6. Check the Engine Speed/Timing Signal
A. Use Cat ET to monitor the following status parameters while you crank the engine:
- "Engine speed primary sensor"
- "Engine speed secondary sensor"
- "Engine rpm from tertiary speed sensor"
- "Primary engine speed sensor timing pattern status"
- "Secondary engine speed sensor timing pattern status"
- "Engine tertiary speed sensor timing pattern status"
B. Ensure that all three of the engine speed sensors are indicating an engine rpm during cranking. Also, ensure that the status of signal patterns for each of the engine speed/timing sensors is "Detected".
Note: The engine will not start if the signal from more than one sensor is missing.
Sensors
Result: The engine speed sensors are OK.
Proceed to Test Step 7.
Result: The engine speed sensors are NOT OK.
Repair: Any of the suspect engine speed/timing sensors, refer to Troubleshooting, "Speed/Timing - Test" for information that is related to troubleshooting the engine speed/timing circuit.
If the problem is not resolved, proceed to Test Step 7.
7. Check the Low-Pressure Fuel System
A. Perform a visual inspection of the fuel system