![]() If the headlamp doesn’t flash, or there’s no voltage to the module or coil pack when the engine is cranked, the problem is most likely in the crankshaft sensor circuit. If the headlamp flashes when the engine is cranked, the DIS module and crankshaft position sensor circuit are functioning. Here’s a little trick that will literally show you if a DIS module and its crankshaft sensor circuit are working: connect a halogen headlamp to the spade terminals that mate the DIS module to the coils.Ī headlamp is recommended here because it puts more of a load on the module than a test lamp. Just remember to add in a maximum of 8,000 ohms of resistance per foot for the plug wires. If measuring the secondary resistance of a DIS coil is difficult because of the coil’s location, try removing the wires from the spark plugs and measure secondary resistance through the plug wires rather than at the secondary terminals on the coils. If readings are outside the specified range, the coil is defective and needs to be replaced. Then connect the ohmmeter leads across the coils’ secondary terminals and compare the secondary resistance reading to specifications (typically 6,000-30,000 ohms). Set the ohmmeter in the low range, and recalibrate if necessary.Ĭonnect the ohmmeter leads across the coil’s primary terminals, and compare the primary resistance reading to specifications (typically less than 2 ohms). First, isolate the coil pack by disconnecting all the leads. Individual DIS coils are tested in essentially the same way as epoxy-filled (square-type) ignition coils. Others, including the newer coil-over-plug systems, have a separate coil for each spark plug. Many DIS systems use the "waste spark" setup where one coil fires a pair of spark plugs that are opposite one another in the firing order. ![]() ![]() But the driveability symptoms caused by a weak coil or dead coil will be limited to one or two cylinders rather than all the cylinders. ![]() The coils in DIS ignition systems function the same as those in ordinary ignition systems, so testing is essentially the same. No spark in only one cylinder or two cylinders that share a coil would tell you a coil has probably failed. So, if there’s no spark and no injector activity, the problem is likely in the crank position sensor. Many engines that are equipped with electronic fuel injection also use the crankshaft position sensor signal to trigger the fuel injectors. No spark in any cylinder would most likely indicate a failed DIS module or crankshaft position sensor. If there’s no spark in one cylinder, try another. On coil-over-plug DIS systems, there are no plug wires so you have to remove a coil and use a plug wire or adapter to check for a spark. If an engine cranks but won’t start, is it fuel, ignition or compression? Ignition is usually the easiest of the three to check because on most engines, all you have to do is pull off a plug wire and check for spark when the engine is cranked. So knowing how to identify and diagnose common DIS problems can save you a lot of guesswork the next time you encounter an engine that cranks but refuses to start, or one that runs but is missing or misfiring on one or more cylinders. Failures can and do occur for a variety of reasons. Consequently, DIS ignition systems are pretty reliable.Įven so, that doesn’t mean they are trouble-free. No distributor means there’s no distributor cap or rotor to replace, and no troublesome vacuum or mechanical advance mechanisms to cause timing problems. on 31 January 2013 10:19 PMĭistributorless ignition systems (DIS) have been around for almost a decade now, and have eliminated much of the maintenance that used to be associated with the ignition system.
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