My son's 2006 Ram 1500 with 4.7L Started running very rough at 2400 RPM and will not go any higher. Engine code that showed on my OBD scanner is showing P2308 " Ignition coil 'C' secondary circuit".
I replaced the coil pak and all the spark plugs. The coil pak I replaced was the second one back on the drivers side. Also when I replaced all the spark plugs, that is the only one that looked like it wasn't firing.
If I remove the fault code with the scanner then start it - it will go over 4000 running smooth until it triggers the fault code again then will only get up to 2400 RPMs then runs very rough, yet will idol
Smooth and runs fairly smooth again until 2400 rpm. I have checked the wiring and nothing looks broken or frayed. I have disconnected both the positive and negitive cables from the battery to reset the pcm..
Still comes up with the P2308 code.
I appreciate any help.
Thank You
Jeff M

 

Swap coil packs on 1 and 3, see if the code follows the coil.

 

I replaced the coil with a new one, I also switched it with another coil that was good and got the same error code. Only thing left that I can think of is the ECM/PCM

 

The code is talking about an 'abnormal' voltage on the secondary circuit..... Not entirely sure just how it determines that...... It *could* be a wiring problem, or yes, it could be the PCM.....

 

Thanks for the reply. The truck sat for for a couple of years, I also noticed the tach doesn't register correctly all the time. Sometimes it is right on, other times it only shows 100 or 200 rpm. I'm thinking the PCM because it sat with no battery or being started for 2 - 3 years.
My son has been driving it for about 8 months now and little gremlins pop up every once in a while.

 

Tach may just be sticky..... The cluster gets all it's info from the communications bus.... It's a little network in your truck. PCM tells the cluster what to display, and the cluster then wiggles gauges and such. I would think it the PCM were actually getting seriously wrong readings from it's sensors, you would have some more significant problems.

 

Thank You, I will have to do so more research, see if I can check the voltage impulse to the coil to make sure it is getting enough power.

 

Should have constant voltage so long as the engine is running.... PCM controls the ground side of the circuit.

 

Since this truck has been put "back into service" after years of sitting, in the 8 months, has it been on a good long drive where a lot of engine heat has been generated for a longer period of time? Perhaps a good 'bake' might do the vehicle well...

Short trips to school, the gym, running local errands might be common...

Hey, If you finally get it fixed, please do us the favor of return and let us know what you learn, point out any good advice, and how you got it all fixed and purring like a kitten nuzzling at moma's teat...

Cheers!

 

LOL, Yes I will let you know, It has been driven long distances, over 250 miles one way.

Thanks
Jeff M