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Home >> GMC >> 1993 >> Forward Control 7.4 N >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - V6 >> Self-Diagnostic Tests >> Code 17, Rpm Signal Problem 3.8L >> Notes
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Code 17, Rpm Signal Problem 3.8L: Notes

NOTE: Test numbers refer to numbers on diagnostic chart.
  1. Verifies spark reference circuit is not shorted to ground or open in ignition jumper harness.
  2. If a window on harmonic balancer is lined up with 18X Hall Effect switch, ignition module will ground spark reference signal. Starter may have to be bumped several times to obtain a voltage reading.
  3. Voltage reading should be lower than reading obtained with engine not running, indicating a pulsed reference signal.