Q: How to replace a pick-up coil in a distributor for Chevrolet Astro?
A: Detach the cable from the negative terminal of the battery. Remove the Distributor cap and rotor. Remove the distributor from the engine. Detach the pick-up coil leads from the module. Connect one lead of an ohmmeter to the terminal of the pick-up coil lead and the other to ground as shown. Flex the leads by hand to check for intermittent opens. The ohmmeter should indicate infinite resistance at all times. If it doesn't, the pick-up coil is defective and must be replaced. Connect the ohmmeter leads to both terminals of the pick-up coil lead. Flex the leads by hand to check for intermittent opens. The ohmmeter should read one steady value between 500 and 1500 ohms as the leads are flexed by hand. If it doesn't, the pick-up coil is defective and must be replaced. Remove the spring from the distributor shaft. Mark the distributor tang drive and shaft so that they can be reassembled in the same position. If the distributor is equipped with a Hall Effect switch attached to the top of the pick-up coil, remove the two retaining screws. Carefully mount the distributor in a soft-jawed vise and, using a hammer and punch, remove the roll pin from the distributor shaft and gear. Remove the distributor shaft. Remove the driven gear and spacer washers from the end of the shaft, making sure to note the order in which you remove any spacers. Remove the shaft from the distributor. To remove the pick-up coil, remove the thin "C" washer (on four-cylinder models) or the retaining clip. Lift the pick-up coil assembly straight up and remove it from the distributor. Note the order in which you remove the pieces. Reassembly is the reverse of disassembly. Installation is the reverse of removal.
Q: How to remove and install ignition coils in different types of ignition systems for Chevrolet Astro?
A: To start the High Energy Ignition (HEI) systems in 1994 and earlier models, disconnect the negative terminal of the battery. Unplug the coil's high tension wire and both electrical leads if it is separately mounted on your model; then take off the coil by removing both mounting nuts. On models with the coil in the distributor cap, either push through the top of the hood and remove it by taking out the mounting screws or lift off the cover after removing the coil cover screws. Between TACH and BAT terminals, measure primary resistance of nearly zero if you want to test a coil; replace it if higher. Measure secondary resistance between rotor button in distributor cap and TACH terminal as well as rotor button and BAT terminal which should not read infinite resistance; otherwise, replace a coil. Have various ohmmeter tests done for a separately mounted coil on models with it; then replace a coil if necessary. To install connect then follow backward removal procedure for COILS. For Enhanced Distributor Ignition (EDI) systems in 1995 and later models, you can check the coil without removing it from the engine by first removing engine cover and air cleaner assembly, then detach primary electrical connector from ignition coil. Determine that there is battery voltage at CONTACT switch ON using a voltmeter or test light when testing this kind of a coil; otherwise inspect fuses plus wiring connections. In case any checks fail during ohmmeter measurement of coils' resistances, change coils accordingly. To remove COILS unscrew studs holding them down to intake manifold after disengaging battery negative terminal, unfasten electrical connectors from ignition coils, separate their secondary wires going into distributors and finally strip down engine covers together with air filter housings. A drill punch should be used to remove an old COIL from bracket before swapping for new. Install new COIL onto bracket securing whole assembly to manifold with studs before continuing with the remaining steps in backward order.