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sprinkles08, Chrysler/Dodge/Jeep master tech
Category: Dodge
Satisfied Customers: 22821
Experience:  ASE Master and Advanced Certified, Chrysler/Dodge/Jeep Master Certified, Trans and Hybrid Specialist
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Dodge Ram 1500: liter..The check engine light came..cylinders

Customer Question

I have a 2003 4.7 liter Dodge Ram 1500 pick up. The check engine light came on and started flashing, the engine is running like its running on 5 or 6 cylinders. the code says ignition coil failure "E and "F, is that the number 5 and number 6 cylinder ignition coil?
Submitted: 8 years ago.
Category: Dodge
Expert:  sprinkles08 replied 8 years ago.

Hello and welcome to JustAnswer!


It does sound like it would be the number 5 and 6 coils. The codes should have been in the form of P0355 and P0356. These shouldn't be bad to diagnose. You should be ok with just a test light. Unplug these two coils. Start the engine and check for power on the dark green/orange wire. If it's ok, check the other wire in the connector for pulsing ground while it's running. Put the alligator clip on battery positive, start the engine and probe the second wire in the connectors. If the test light flashes and you found the 12v feed on the first wire ok, replace the coils.

Customer: replied 8 years ago.

It did this a couple of weeks ago, but after stopping the engine and restarting it cleared up. Todayit want clear up. Is it unusual for two coils to go bad at the same time? we have been having 99 and 100 degree heat for the last couple of weeks, would that be a factor if the coils were weak? Thanks

Expert:  sprinkles08 replied 8 years ago.
The key is testing it while it's acting up. If it won't clear up now it would be the best time to check it out. It could very well be the coils, and they do fail sometimes, but it could also be wiring or even the coil driver logic inside the engine controller itself. It's really hard to say what it is, I would test it with it acting up just in case it's something else before spending the money on coils. It wouldn't be all that likely for two coils to stop working and start working again at the same time.
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Customer: replied 8 years ago.

I checked the codes and they were PO300, PO355 and PO356 primary and secondary ignition coils. I then unplugged them and ran the test with the tester both plugs had a constant 12 volt and a pulsing ground. I then changed out both coils. I cleared off the old codes and ran the test again, as soon as I started the engine the check engine light light came on and the two diagnostic codes re-appeared, PO355 and PO356. What can I do now? Thanks

Expert:  sprinkles08 replied 8 years ago.
You've got to check it while these cylinders are dead. If the coils are new, while it's acting up you are going to be missing either the ASD 12v feed or the coil driver. The ASD feed is common to all injectors and coils, the driver's are individual. If you are missing ASD while the cylinders are dead you've got a broken wire somewhere, if you are missing the coil drivers you would then have to check right at the pcm. If you had the drivers at the pcm but not the coils you have a wiring issue, if there are no drivers at the pcm it's bad.
Customer: replied 8 years ago.
I did check them dead, I had both unplugged and then I started the engine. With the engine running and both unplugged I ran the test I had ASD/common feed on both plugs. I also had the pusling ground on both. I assume that is what you are calling the individual drivers. After the test I thought the coils must be bad that is why I changed them, but like I sais the check engine light came back on after being manually cleared off and the truck still runs like crsp with the same two codes showing up. I know you must be telling me something I don't understand, so if you could further explain. Thanks
Expert:  sprinkles08 replied 8 years ago.

Have you pulled the plugs on those cylinders?


I'd like to get a look at the plugs, and while the coils are back out check for spark on these cylinders. Make sure not to dry fire the coils because you can take out a coil driver (if they're all still good anyway).


Another thing I'd like to make sure is that you replaced the correct coils. The left bank (driver's side in the US) is the odd bank, right bank is even. Number 5 is the second to last cylinder back on the left side, 6 is the second to last on the right bank.