H1 V8-6.5L DSL (1998)
Diesel MFI Pump: Testing and Inspection
Figure 3-18: Stepper Motor Replacement
Figure 3-19: Injection Timing Stepper Motor Circuit
A stepper motor fault will affect desired and measured injection timing degree readings on the scan tool. A difference of 5° or more between the readings
indicates a motor fault.
Stepper Motor Test
1. Connect the scan tool to the diagnostic/data link connector.
2. Start and run the engine until it reaches the normal operating temperature.
3. Note injection timing readings on the scan tool.
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If "desired" and "actual" injection timing readings differ by 5° or more, continue the test.
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If readings are no more than 3°-4° apart, but a trouble code was set, the problem is intermitent and probably caused by a bad connection
between the PCM and the motor.
4. Stop the engine and turn ignition to Off.
5. Check the resistance between terminals A7 and A8 of the brown 24 pin PCM harness connector (C29) for coil 1 low (A8), and coil 1 high (A7)
(Figure 3-19).
