RELAY AS 1557042 - Caterpillar

The diagnostic module operates on 12 DCV to 24 DCV. While the vehicle is being operated the diagnostic module requires a constant current. The diagnostic module requires a current of 50 mA and a maximum of 150 mA. When the vehicle is not running the diagnostic module requires only a few mA. The small amount of current reduces the chance of battery drain. The diagnostic module has the ability to store 65,000 records internally. The diagnostic module is equipped with a lithium battery backup for unexpected power interruptions. The lithium battery has an expected life of ten years. The pressure transducer can not be replaced. The pressure transducer range is 0 to 20 in Hg. The thermocouple has an operating temperature range of 0 to 1000°C (32° to 1832°F).
Illustration 1 g00885031
Diagnostic module (1) 4 Mounting holes (2) "System status" light (3) "Over-pressure alarm" light (4) "Over-temp alarm" light (5) "System problem" light (6) "Alarm reset button" (7) "Pressure transducer port" (8) "Wire passage" (9) "Serial data comm port"The diagnostic module is equipped with alarms to warn you about the operation of the exhaust. The diagnostic module has the following features:
Mounting holes are used to secure the diagnostic module to the vehicle.
"System status" light is green. The light will blink in two second intervals. This indicates that the system is working properly.
"Over-pressure alarm" is activated when the exhaust back pressure has exceeded the programmed value. "Over-pressure alarm" activates the engine derate.
"Over-temp alarm" is activated when the exhaust temperature exceeds the programmed value.
System problems will activate the warning light when there is a problem with the diagnostic module.
"Alarm reset button" will clear active alarms. Clearing the alarms will deactivate the derate.
"Pressure tranducer port" is the location for the copper tubing which measures the exhaust back pressure.
The wires enter the diagnostic module through the wire passage.
"Serial data comm port" will allow the technician to view the logged data. The logged data will show the changes of the pressure and the temperature of the exhaust system. The technician can also view the temperature and pressure of the exhaust system when the engine is running. The alarms are displayed to the driver in the form of an amber light and red light. The lights get the signal from the diagnostic module. Refer to Operation and Maintenance Manual, SEBU7011 for additional information.The parameters of the diagnostic module are listed in Table 1.
Table 1
System over temperature    
    Active alarm    
Log the events that caused the alarm.
Output 1
Output signal is activated during the alarm.
Activate the alarm above
650° 20°C (1202° 36°F).
Activate the alarm for 60 seconds.
System over pressure    
Warning     Active alarm    
Log the events that caused the alarm.
Output 1
Output signal is activated during the alarm.
Activate the alarm when the pressure is above 7 in Hg for more than 5% of the time in a 60 minute interval.
Alarm     Active alarm    
Log the events that caused the alarm.
Output 2
Output turned on.
Activate the alarm above 8 in Hg when the value is