542 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
V
REF
Pin-Point Diagnostics
Voltage Reference Connector Checks (If multiple DT C s are set, remove harn ess connections and
measure V
REF
at suspected sensor circuits.)
Sensor
Test Point
Spec Comment
EBP 2tognd 5V±0.5V
MAP 2 to gnd 5 V ±0.5 V
ICP
B to gnd
1
5V±0.5V
APS C to gnd
5V±0.5V
BAP 2tognd 5V±0.5V
EOP
2tognd 5V±0.5V
BCP (optional)
B to gnd
1
5V±0.5V
EFP (optional)
2tognd 5V±0.5V
WIF (optional)
B to gnd 5 V ±0.5 V
Check V
REF
at each sensor. To isolate area of short
or open circuit, identify sensors without V
REF
and
sensors that share a common V
REF
.Ifdisconnecting
asensorcausesV
REF
to be present in the circuit that
had no previous V
REF
, it is likely that the disconnected
sensor had shorted V
REF
to ground.
1
Test point Pin B is at vavle cover pass through conn
ector. If additional testing is needed, test point Pin 2 should b e use d
at under valve cover connector.
WA RNING: To avoid serious personal injury, p
ossible death, or damage to the engine or vehicle,
always disconnect main negative battery cab
le first. Always connect the main negative battery cable
last.
Connector Checks to Chassis Ground (Turn the ig nition switch to OFF. Disconne ct sen sors and negative
battery cable.)
Sensor
Test Point
Spec Comment
EBP 2tognd
>500 Ω
MAP 2 to gnd
>500 Ω
ICP
B to gnd
1
>500 Ω
APS C to gnd >1 kΩ
BAP 2tognd
>1 kΩ
EOP
2tognd
>500 Ω
BCP (optional)
B to gnd
1
>500 Ω
EFP (optional)
2tognd
>500 Ω
WIF (optional)
B to gnd
>500 Ω
If resistance is < spec, check for short to ground. If a
short to ground condition exists, remove all sensor
connectors that are connected to V
REF
and ECM.
Inspect to determine if short is in sensor, ECM, or
wiring harness. Spec is >1 kΩ with all common
sensors disconnected from harness.
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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