Navistar N9 Diagnostic Manual page 48

44 1 DIAGNOSTIC TROUBLESHOOTING PROCEDURES
Step
Determine if EST communicates with other modules.
3
A. Key-On Engine-Off (KOEO)
B. Connect EST with ServiceMaxx™ to initial vehicle and log in.
C. Under the Connection (Sniffer) tab verify equipped modules are listed
under Module Name and Count is actively changing.
Does EST communicate with modules other than the Engine Control Module
(ECM)?
CAUTION: Always use the latest version of N9 and N10 Engine and Aftertreatment Wiring Schematic Form
0000003481. Failure to comply will cause misdiagnosis and unnecessary repairs.
Step Determine if Engine Control Module (ECM) ground circuits are working
4 properly.
A. Key Off
B. Connect Breakout Harness 00-00959-01 to ECM 76-pin gray chassis
connector and ECM.
C. Connect Breakout Harness 00-00959-01 to 180-pin Breakout Box
00-00956-08.
D. Key-On Engine-Off (KOEO)
E. Measure voltage between battery positive and pins C-2, 4, and 6.
Are ECM ground circuits between pins C-2, 4, 6 and battery positive within 0.5V
of battery voltage?
Step
Determine if ECM is receiving ignition switch power.
5
A. Key-On Engine-Off (KOEO)
B. Measure SWBAT circuit voltage between battery ground and pin C-31.
Is voltage between pin C-31 and battery negative within 0.5V of battery voltage?
Decision
Yes: Go to Step 4
No: Go to Step 15
Decision
Yes: Go to Step 5
No: Repair ground circuits. After
repairs are complete, retest for
original problem.
Decision
Yes: Go to Step 7
No: Go to Step 6