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Ignition/Tuner/ECM/Fuel InjectionNeed advice on ignition issues? Questions about a tuner? Have questions about a EFI calibration or Fuel Injection? Tips on Engine Diagnostics, how to get codes, and what they mean. Find your answers here.
the power doesn't come from the coil it comes from the ecm so it should give me power to power up the coil when I turn the ignition on. that's the only way to get power to the coil has to come from the ecm I took the cover off the plug to the ecm its still plugged in and I can see all of the terminals at the ecm the same color wire as the one from the ecm has 12 volt
so if the ecm is still plugged in don't you agree that I should get 12 volt to the center wire on the coil even if its not plugged into the coil?
Yes but as far as I know power does not come from the ECM, it comes from the system relay. At least it does on early TCs with delphi. System relay supplies power to both the coil and ECM. Get a service manual.
Here are the three pages of flow charts from the 98 SM. Walk through them. If it is the coil they should help. They are a bit out of order. The second page should be first and the first page should be second.
Max is 100% correct on the 12V+ not coming from the ECM. Also, it one cylinder has spark, the coil has the 12V+ signal. You are looking at the ground side for your problem. From the descriptions above, it appears you have one of several things going on. 1) Bad new coil, 2) Bad aftermarket fuel/ignition controller such as a powercommander - you say you do not have, 3) broken or corroded wire between ECM and coil, 4) Bad ignition module in cam cover 5) Bad ECM, if that's the case and you cannot find one pm me.
You will only have 12V+ to the coil when the system is powered up and the crank sensor sees a signal (except for key on). You will most likely see it for 2-3 seconds at key on and it will go away if you do not crank the engine. When you start cranking the engine and the relay powers it back up, you will see it again.
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