850781 Mercruiser HARNESS-EXTENTION 4M

Illustration 1 g00481278
System Schematic For Alarm Module (ALM)
All the fault indicators of the remote annunciator flash and/or all the fault indicators of the control panel alarm module flash. The indicators flash once per two seconds (0.5 Hz).Note: The maximum number of modules (Alarm, Remote Annunciator, or Customer Interface Module), that can be connected to the GSC is three. (There is no limit on the number of Custom Alarm Modules that can be used in an application.) The maximum distance between a module and the GSC is 305 m (1000 ft). If these specifications are not met, the information on the data link can be erratic. Also, the indicators on the alarm module could flash. If the conditions are not in compliance with the specifications, reduce the number of modules and/or shorten the distance to the GSC.The data link will malfunction under the following conditions with multiple modules:
One of the modules is powered down. ("B+" or "B-" is disconnected.)
The module that is powered down remains connected to the data link.Under these conditions, the indicators that are controlled by the data link of the other modules that are powered up will flash at .5 Hz.
Check the data wire.
Turn the ECS to OFF/RESET.
Disconnect the harness connector from the GSC.
Check for an open. Measure the resistance from terminal 2 of the alarm module to contact 35 of the GSC harness connector. The resistance should be 5 ohms or less.
Check for a short. Measure the resistance from contact 35 of the GSC harness connector to the battery (B+) and ground (B−) at the relay module. The resistance should be greater than 5000 ohms. Expected Result: For 1c, the resistance should be 5 ohms or less. For 1d, the resistance should be greater than 5000 ohms.Results:
OK - All resistance measurements are correct. Proceed to next step.
Not OK - One or more of the resistance measurements are NOT correct. Therefore, the harness wiring with the incorrect resistance is faulty. Troubleshoot the faulty wiring and repair the faulty harness wiring. STOP.
Measure the voltage at the alarm module. The ECS remains in the OFF/RESET position.
Reconnect the harness connector to the GSC.
At the alarm module, measure the DC voltage from terminal 2 to terminal 7. The voltage will be changing. The voltage should be between 1 and 10 DCV. Note: If you are troubleshooting a remote annunciator, measure the DC voltage from contact 35 to contact 31 of the GSC harness connector. Make the measurement by using the 7X-1710 Multimeter Probe Group. Do not disconnect the harness from the GSC. This voltage measurement should agree with the preceding measurement of 2b. If the voltages do not agree, the wire is faulty. The wire is faulty from terminal 2 of the remote annunciator to the terminal in the internal panel.
Disconnect all wires from terminal 2 of the alarm module. Again measure the DC voltage from terminal 2 to terminal 7 at the alarm module. The voltage should be 10.5 1.0 DCV. Expected Result: For 2b, the voltage should be between 1 and 10 DCV. For 2c, the voltage should be 10.5 1.0 DCV.Results:
OK - Both voltage measurements are correct. Therefore, replace the alarm module. STOP.
Not OK - Both voltage measurements are low. Therefore, replace the alarm module.
Not OK - The first measurement is low and the second measurement is high. Therefore, replace the GSC. See Testing And Adjusting, "EMCP Electronic Control (Generator Set) - Replace". STOP.