Navistar N9, Diagnostic Manual

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1 DIAGNOSTIC TROUBLESHOOTING PROCEDURES 41
9.0 - Engine Compression Brake Operational Checkout Procedure
Step
1
Perform preliminary operational checkout procedure. Decision
Did you perform 1.0 Preliminary Vehicle Operational Checkout Procedure? Yes: Go to Step 2
No: Go to 1.0 Preliminary Vehicle
Operational Checkout Procedure
(page 23).
Step
2
Check for related Diagnostic Trouble Codes (DTC). Decision
Using Electronic Service Tool (EST) with ServiceMaxx™, check DTC list for:
• SPN 191 Transmission Output Shaft Speed (TOSS) Vehicle Speed Sensor
(VSS)
• SPN 597 Engine Compression Brake Switch
• SPN 4287 Engine Compression Brake Pressure (ECBP)
Does EST DTC list have any of the above listed SPN?
Yes: Go to Fault Code Diagnostics
for appropriate SPN.
No: Perform 0 to 60 MPH Test
(page 2236) while symptom is
occuring, activate engine brake and
deactivate engine brake. Go to
Step 3
Step
3
Determine if engine compression brake is operating, or is engaged when
not commanded On.
Decision
Review 0 to 60 snapshot
Does engine brake activate and deactivate properly when commanded?
No, engine brake does not activate:
Go to 9.1 Engine Compression
Brake Inoperative (page 126).
No, engine brake does not
disengage when commanded Off:
Go to 9.2 Engine Compression
Brake Engaged When Not
Commanded (page 129).
Yes: Review operator complaint