Bcp Circuit Operation - Navistar International DT 466 Diagnostic/Troubleshooting Manual

320 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS

BCP Circuit Operation

Figure 387 BCP circuit diagram
The BCP sensor is supplied with a 5 V reference signal
at Pin 2 through the valve cover gasket Pin B from
ECM Pin X1–14. The BCP sensor is supplied a signal
ground at Pin 1 through the valve cover gasket Pin C
from ECM Pin X1–6. The BCP sensor sends a signal
from sensor Pin 3 through valve cover gasket Pin A to
ECM Pin X2–11.
Fault Detection / Management
The ECM continuously monitors the signal of the BCP
sensor to determine if the signal is within an expected
range. If the ECM detects a voltage greater or less
than expected, the ECM will set a DTC and illuminate
the amber ENGINE lamp.
BCP Diagnostic Trouble Codes (DTCs)
DTCs are read using the EST or by counting the
flashes from the amber and red ENGINE lamps.
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
DTC 126
BCP signal out-of-range low
• DTC 126 is set by the ECM if signal voltage is less
than 0.039 V for more than 0.35 second.
• DTC 126 can be set due to an open or short to
ground on the signal circuit, a failed BCP sensor,
an open V
• When DTC 126 is active the amber ENGINE lamp
is illuminated.
DTC 127
BCP signal out-of-range high
• DTC 127 is set by the ECM if the signal voltage is
greater than 4.9 V for more than 0.35 second.
• DTC 127 can be set due to a signal circuit shorted
to V
• When DTC 127 is active the amber ENGINE lamp
is illuminated.
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
circuit or V short to ground.
REF REF
or B+, or a failed BCP sensor.
REF