Distributor Pick-Up Coil Short & Resistance Checks

1. Disconnect pick-up coil leads from HEI (EST) module terminals "N" and "P" (usually Green and White). Set ohmmeter to middle range and connect one lead to either pick-up coil lead and the other lead to distributor housing. Flex pick-up coil leads by hand to check for intermittent shorts. Reading should be infinity at all times. If not, replace pick-up coil.
   Fig 1: Checking Distributor Pick-Up Coil Integrally mounted ignition coil is shown. Courtesy of General Motors Corp.

   
2. Connect ohmmeter between both pick-up coil leads. Check for intermittent opens by flexing wires and connectors. Resistance should be 500-1500 ohms. If not, replace pick-up coil.

Fig 2: Checking Distributor Pick-Up Coil Externally mounted ignition coil is shown. Courtesy of General Motors Corp.

Fig 3: Checking Distributor Pick-Up Coil Illustration applies to sealed module connector distributors only. Courtesy of General Motors Corp.