7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS 357
CMP Pin-Point Diagnostics
Figure 411 CMP circuit diagram
Sensor an d Circuit Resistance Check (Check with breakout box connected [X1 only] to engine harness
only and CMP sensor connected. Disconnect chassis connector 9260
1
. Inspect for bent pins or corrosion.)
Test Point
Spec Comment
X1–9 to X1–10
300 Ω to 400
Ω
Resistance through sensor and complete circuit. If not within spec,
do Sensor Resistance Check. If in spec, check for s hort to ground
or open within wiring.
X1–9 to Pin A (9260) 300 Ω to 400
Ω
Resistance through sensor and complete circuit. If not within spec,
do Sensor Resistance Check. If in spec, check for s hort to ground
or open within wiring.
Sensor Resistance Check (D
isconnect harness from sensor. Note: Test point to sensor only.)
1to2
300 Ω to 400
Ω
If within spec, check for short to ground or open within wiring.
If not within spe c, replace sensor.
Connector Resistance Checks to ECM Chassis Ground (Turn the ignition switch to OFF. Disconnect
harness from sensor. Disconnect chassis connector 9260
1
.)
X1–9 to Pin A (9260) > 500 Ω If < 500 Ω, check for sho
rt to ground within wiring harness.
X1–10 to Pin A (9260) < 5 Ω If > 5 Ω, check for open circuit within wiring harness.
WARNING: To avoid serious personal injury, possible death, or damage to the engine or vehicle,
always disconnect main negative battery cable first. Always connect the main negative battery cable
last.
Connector Resistance Checks to Chassis Ground (Turn the ignition switch to OFF. Disconnect chassis
connector 9260
1
. Disconnect negative battery cable. Disconnect harness from sensor. Use disconnected
negative battery cable for ground test point.)
X1–9 to gnd cable
>1kΩ If < 1 kΩ, check for short to ground.
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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