7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS 371
ECL Circuit Operation
Figure 419 ECL circuit diagram
The coolant level sensor uses a floating ball with a
magnetic switch. When the coola nt level is full, the
float will rise and the magnet will pull the level switch
open. This allows a 5 V signal at ECM Pin X3–4.
When the level is low, the switch will close and ECM
PinX3–4willbe0V.
Fault Detection / Management
The ECM continuously monitors the ECL circuit for
in-range faults. The ECM does not detect open or
short circuits in the ECL system. When the ECM
detects an in-range fault, DTC 236 will be set.
ECL Diagnostic Trouble Codes (DTCs)
DTCs are read using the EST or by counting the
flashes from the amber and red ENGINE lamp.
DTC 236
ECLswitchcircuitfault
• DTC 236 is set when the ECM detects an in-range
fault voltage and the voltage is between 3.4 V and
4.3 V at ECM Pin X3–4 for more than 2.0 seconds.
• DTC 236 is set when a high resistance connection
or intermittent short to ground in the circuit exists.
• DTC 236 will not illum ina te the red ENG INE lamp.
If the condition is intermittent, the DTC will be
logged as inactive.
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
• Digital Multimeter (DMM)
• Breakout Box
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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