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Ignition problems- unsure how to proceed

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Old 03-06-2016, 02:10 PM
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Default Ignition problems- unsure how to proceed

Here's what I've got going on: about a month ago I purchased a 99 dodge ram 2500 5.9l 4x4 at an auction for a very reasonable price. As a preface I'd like to add I'm no mechanic. When I got it, it was throwing several codes and I've been whittling those down as my pocketbook allows. Last Wednesday, after several rainy days, it would not start after work. I scanned the codes and came up with a camshaft position sensor fault. I cleared it (without recording the code number ) hoping maybe it was a glitch in the matrix. no such luck. I did some research and it did seem like it was a possible fix, and the computer said it was broken, so I replaced it. I could smell gas, so it seemed that spark was the issue. This was not the fix to my problem. Next I tried a spark check off my coil wire- nothing. I did resistance measurements on the coil wire and came up 5 M OHMS. I then figured the coil wire was the culprit and replaced it. Again, no such luck. My next action was the coil, R&R with no results. I swapped the starter relay with a suspected good one. Nothing. I'm now fearing the pcm or some other expensive part is at fault. I don't know how to check the computer and I'm unsure where to proceed. does anyone have any suggestions? Any help would be appreciated.
 
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Old 03-06-2016, 02:16 PM
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Failure to start after a lot of rain tells me the spark plug wires are worn. Is it even turning over?

Originally Posted by TheAlmightyBeantotem
I cleared it (without recording the code number ) hoping maybe it was a glitch in the matrix. no such luck. I did some research and it did seem like it was a possible fix, and the computer said it was broken, so I replaced it.
The "computer" said something was broken and you replaced "it"? What exactly did you replace? No spark from the coil sounds like the coil isn't being told to fire, so there is some more digging around to be done.
 
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Old 03-06-2016, 02:22 PM
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it was turning over and there was the smell of gas, seemingly ruling out a fuel supply problem. I replaced the camshaft position sensor. research stated that it could cause individual cylinder misfires, an issue I was dealing with. I ruled out spark plug wires because it was working fine in the morning and in the afternoon there was no spark. it did not seem to me that all the wires would fail in 9 hours. and no spark was coming from the coil. I agree that the coil isn't being told to fire. haven't tracked down why though. thank you for the response.
 
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Old 03-06-2016, 02:30 PM
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Cam sensor controls injector timing. If it is off, the engine will run, maybe, if it does, it will run like dog poo. Need to see if the coil is being told to fire. Test light across the terminals for the coil connector will tall you that.
 
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Old 03-06-2016, 02:32 PM
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copy. i'll give that a shot. should I be looking for a flashing light?
 
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Old 03-06-2016, 02:34 PM
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Yep.
 
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Old 03-06-2016, 02:51 PM
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Originally Posted by HeyYou
Cam sensor controls injector timing. If it is off, the engine will run, maybe, if it does, it will run like dog poo. Need to see if the coil is being told to fire. Test light across the terminals for the coil connector will tall you that.
Also note that timing on these trucks is controlled by the PCM and cannot be adjusted.
 
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Old 03-06-2016, 02:58 PM
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no flashing light at the coil plug. does anyone know where I can find the coil output from the pcm?
 
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Old 03-06-2016, 03:40 PM
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I assume the input to the ignition coil comes from the pcm. is that even close?
 
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Old 03-06-2016, 03:44 PM
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PCM controls ground circuit for the coil. You should see 12 volts at the coil connector for about three seconds after the ignition is turned on, or, while engine is cranking.

Begins to sound like the crank sensor took a dump. It's behind the passenger side head, and reads from the flexplate. (or, flywheel, if manual trans.)

You can download the service manual for your truck from this thread.
 


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