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Run the initialization again and observe all gauge pointers. Then find the symptom
in Table 5-5 that best describes what you see and follow the instructions.
Symptom
A J1708 data bus gauge* pointer
sweeps.
A non-J1708 data bus gauge pointer
sweeps.
Several (but not all) gauge pointers
sweep.
The SMC and all J1708 data bus gauge*
pointers sweep, SMC displays NO
DATA (may take a couple of minutes
to appear).
All J1708 data bus gauge pointers*
except the SMC pointer sweep.
All gauge pointers except the SMC
pointer sweep.
Only the SMC pointer sweeps, and no
messages appear.
SMC pointer sweeps, SMC displays
NO DATA (may take a couple of min-
utes to
appear).
* Notes: J1708 data bus gauges are gauges whose data is sent from the Engine ECU to the Inter-
face Module over the J1708 data bus. The SMC, Tachometer, Engine Oil Temperature, Engine
Oil Pressure, Engine Coolant Temperature, Manifold Boost, and Engine Load % gauges are all
J1708 data bus gauges
Data for the remaining gauges is sent directly to the Interface Module through connectors J3 and
J4 (various temperature inputs, fuel level, etc.) or through direct connections to the pressure and
vacuum transducer modules.
Probable Cause
Action
No data from Engine
Go to Section 5.5.1 on
ECU.
page 5-26.
Interface Module in-
Go to Section 5.5.2 on
correctly programmed.
page 5-26.
Private data bus wires
Go to Section 5.5.3 on
open between the
page 5-27.
gauges.
Defective part on J1708
Go to Section 5.5.4 on
data bus.
page 5-27.
J1708 data bus open
Go to Section 5.5.5 on
between Engine ECU
page 5-29.
and Interface Module.
Private data bus open;
Go to Section 5.5.6 on
defective component
page 5-30.
on private data bus.
No speed data from
Go to Section 5.5.7 on
Engine ECU.
page 5-32.
J1708 data bus open
Go to Section 5.5.8.
between Engine ECU
and SMC.
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