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Pick-Up Coil

NOTE: Activation of the vacuum advance may align trigger wheel tooth and pick-up coil pole piece causing ohmmeter pointer to deflect. This deflection should not be diagnosed as a faulty pick-up coil.
  1. Isolate 2 pick-up coil lead wires. Remove pick-up coil connector from module. Connect ohmmeter to either terminal and ground. See Fig 1. Connect pump and apply vacuum to test vacuum advance unit. Replace vacuum advance unit if inoperative.
  2. Attach ohmmeter to either pick-up coil terminal and distributor housing. Select mid scale. Operate vacuum pump and observe ohmmeter throughout vacuum range. Reading should be infinite at all times. If not, replace pick-up coil. See meter "A" in Fig. Fig 1.
  3. Attach ohmmeter to both pick-up coil connector terminals. Operate vacuum pump and observe ohmmeter throughout the vacuum range. Replace coil if reading is not infinite at all times. See meter "A" in Fig. Fig 1.
  4. Connect ohmmeter to pick-up-coil terminals. Operate vacuum pump and observe ohmmeter throughout the vacuum range. Flex terminal wires by hand to check for possible intermittent defects in wiring or connectors. Replace pick-up coil if resistance is not 500-1500 ohms at all times.
Fig 1: Pick-Up Coil Test Connections
G9013Courtesy of GENERAL MOTORS CORP.