882751A 3 Mercury RELAY KIT, Trim

Table 1
Diagnostic Codes Table
Code and Description Conditions which Generate this Code System Response
91-8 Throttle Position Sensor abnormal frequency, pulse width, or period The Electronic Control Module (ECM) detects a signal frequency for the primary throttle position sensor that is below 150 Hz or the frequency is above 1050 Hz. The engine must be running in order for this code to be logged.
The ECM flags the throttle position as invalid data and a default value of zero percent is used. The engine speed is limited to low idle.
91-13 Throttle Position Sensor calibration required The ECM detects a duty cycle for the primary throttle position sensor that is below 5 percent or a duty cycle is above 95 percent.
1249-8 Secondary Throttle Position signal abnormal The ECM detects a signal frequency for the secondary throttle position sensor that is below 150 Hz or the frequency is above 1050 Hz.
1249-13 Secondary Throttle Position Sensor calibration required The ECM detects a duty cycle for the secondary throttle position sensor that is below 5 percent or a duty cycle is above 95 percent. Note: If the vessel is equipped with a Multi-Station Control System (MSCS), refer to Service Manual, RENR7651, "Marine Multi-Station Control System" for additional information that is related to troubleshooting the speed control circuits.Note: When you make repairs to the circuit for the Throttle Position Sensor (TPS), follow the guidelines that are found in Special Instruction, REHS1187, "Electronic Installation Guide". This document provides information that ensures that the TPS is protected from transient voltages and from problems that are caused by improper grounding.Note: If one of the above diagnostic codes is active, troubleshoot that code before you continue with this procedure. If you suspect a problem with engine synchronization, refer to Troubleshooting, "Synchronization - Test".A problem with the circuit for the synchronization switch may prevent the ECM from responding to a valid signal from the TPS. The following active diagnostic codes will also prevent the ECM from responding to the throttle input:
91-13 Throttle Position Sensor calibration required
1249-13 Secondary Throttle Position Sensor calibration requiredIf one of the above diagnostic codes is active, troubleshoot that code before you continue with this procedure. If you suspect a problem with engine synchronization, refer to Troubleshooting, "Synchronization - Test".The TPS provides the throttle signal to the engine's ECM. The output for rated speed is a Pulse Width Modulated Signal (PWM) at a constant frequency. The TPS produces a minimum duty cycle in the lowest position and a maximum duty cycle in the highest position of the sensor. When the sensor is in the lowest position, the ECM translates the sensor's output signal to a throttle position of 0 percent. When the sensor is placed in the highest position, the ECM translates the output signal to a throttle position of 100 percent.The throttle position sensor is powered by keyswitch power. The return for the circuit is provided by the −Battery circuit.The ECM uses an automatic calibration function that allows the ECM to maximize the usable range of the sensor. The automatic calibration function assumes a range of PWM duty cycle at powerup. If the duty cycle of the sensor exceeds this initial range, the automatic calibration function adjusts the limits of the duty cycle in order to adjust for the new range.The throttle signal is valid when the duty cycle is in the range of 5 to 95 percent. If the ECM determines that the throttle signal is invalid, the engine rpm will be set to the programmed low idle.Two throttle position sensors are shown in Illustration 1. A vessel may contain more than one TPS. Each TPS may be connected to more than one ECM. Refer to the vessel's schematic diagram for the actual configuration. Use this procedure to troubleshoot all possible configurations.
Illustration 1 g01371189
Schematic for the speed control circuit (typical example)
Table 2
Troubleshooting Test Steps Values Results
1. Verify that the "Secondary Throttle Enable Status" Parameter is Programmed Correctly
A. Remove electrical power from the ECM.
B. Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
C. Restore electrical power to the ECM.
D. Establish communication with the ECM.
E. Verify that the "Secondary Throttle Enable Status" parameter is programmed correctly.
a. If the engine is equipped with a single TPS, verify that the "Secondary Throttle Enable Status" parameter is programmed to "Disabled".
b. If the engine is equipped with multiple throttle position sensors, verify that the "Secondary Throttle Enable" parameter is programmed to "Enabled".
The "Secondary Throttle Enable" parameter is programmed correctly.
Result: The "Secondary Throttle Enable" parameter is programmed correctly.
Proceed to Test Step 2.
Result: The "Secondary Throttle Enable" parameter is not programmed correctly.
Program the "Secondary Throttle Enable" parameter to the correct value. Verify that the repair eliminates the problem.
Illustration 2 g03129657
Location of the connectors that are for the speed control (left rear engine view)
(1) Engine interface connector
(2) J1/P1 ECM connectors
Illustration 3 g01371286
Terminal locations at the P1 ECM connector that are for the speed control
(P1-61) −Battery
(P1-66) Primary throttle signal
(P1-68) Secondary throttle signal
(P1-70) Keyswitch
Illustration 4 g01371296
Terminal locations at the engine interface connector that are for the speed control
(Terminal 2) −Battery
(Terminal 4) Secondary throttle signal
(Terminal 10) Primary throttle signal
(Terminal 30) Keyswitch
Illustration 5 g01159881
Terminal locations at the connector for the throttle position sensor
(Terminal A) −Battery
(Terminal B) Keyswitch
(Terminal C) Throttle signal
Table 3