ECU replacement

[Dabudesigns]

Have a 2017 Lone Star 5.7 hemi. Have had issues that I thought would have disappeared with replacement of ignition coils, spark plugs, deactivation solenoids, camshaft and crankshaft position sensors. As to this point the codes are still there. The main codes are the deactivation ones and now getting a misfire in cylinder 7. I have been told that the ECU is vehicle specific even though part number are the same for many years. Is it possible to get a new ECU and plug it in without programming it? Possible to get a salvage one and save a few bucks? Thanks for any help.

 

[Tach_tech]

It has to be programmed to your truck. What makes you think it needs a PCM?

 

[Dabudesigns]

Just picking the next piece. I changed all items that the codes were referring to. As I mentioned. I replaced all ignition coils and sparkplugs when I got the misfire code in cylinder 7. Still there. Changed all 4 deactivation solenoids. Still there. Camshaft and crankshaft sensors. Still there. I was just trying to go to the next item that controls them. I don't know why the codes are not clearing. I have pulled the battery to let it reset. Codes go away on the first start but after I shut off and restart there they are again.

 

[chri5k]

I think the next thing in the chain from the sensors are the connectors and wiring harnesses that connect them to the ECU. When I see multiple issues in the same general physical vicinity I think wiring harness, grounds, etc. Something that is common to all the sensors.

My daughters car had an intermittent issue detecting the key fob. Service writer said it needed a new BCM. The technician started testing all the wiring going to the BCM and found a bad wire. Smart technician. He earned more money on the labor to find / repair the bad wire than he would have earned putting in a new BCM. The repair cost me less than a new BCM and labor to install it. Plus the technician would have had a come-back since the bad wire would have affected the new BCM.

 

[Dabudesigns]

Ok. I'll do that next. Got the truck out of Texas and looks like some alternative wiring was done to the gas tank and a couple other areas. There are wires cut and spliced at the main harness near the ecu.

 

[Tach_tech]

You can’t just change the part that the code refers too. The codes don’t mean that part is faulty, it means there’s an issue with that system. You still have to diagnose what’s wrong.

What are the actual codes you getting? Like the PXXXX. That will help.

 

[Dabudesigns]

 

[Tach_tech]

For the MDS codes I’d be looking at the intermediate connector by the back of the intake. I’d be testing all the wiring from the PCM to the solenoid to make sure there is no opens or shorts.

Have the lifters ever been changed? Possibly swapped for non mds lifters?

For the cam issue, have you taken out the VCT solenoid underneath the intake. It’s somewhat common for the screens on the solenoid to come apart.

 

[Dabudesigns]

I had to have the camshaft replaced. Ran fine one minute, next minute wouldn't start then when it did truck shook like crazy. I changed everything I could while it was apart. VCT included. The shop I took it 'accidentally ' put the driver side manifold gasket on backwards.

 

[Tach_tech]

Ok, so if you clear all the codes do they come back right away? Engine runs rough?

 

[Dabudesigns]

Yes. Will say there's a misfire in cylinder 7 along with all the deactivation errors.

 

[Scottly]

You have a 2017 that has had the wiring harness hacked this early in it's life. THAT is the larger, looming question. So, what year was hurricane Harvey and all those floods down in Texas?? Before you replace any more parts, you need to do some pin tracing, maybe even a factory harness replacement...Or a "for sale" sign.

 

[Tach_tech]

Yes. Will say there's a misfire in cylinder 7 along with all the deactivation errors.

Ok, with all those codes I would really be looking at a wiring harness issue first. PCM failures are really not that common on these trucks. You’re going to have to test all the circuits from the PCM. Thats what I would be doing if I came across this at my shop.

 

[Dabudesigns]

I know this is a long shot and loaded question, is there a site that contains the diagram so I can see what and if wires are inop?

 

[demonram]

Just curious about the misfire code. If you find that there is a wiring issue and correct it, and that clears the codes, good for you. If you find a wiring issue, fix it, and still get a misfire code, you probably have a lifter gone bad. Hope you find the issue. Let us know on here what the problem was. Like someone else said earlier, a 4 year old truck most likely shouldn't have had an issue with the ECM. My 2011 Sport has right at 145,000 miles on it. No issues with the module at all.

 

[Atcer2018]

Have you checked the #7 cylinder plug and fuel injector?

 

[Dabudesigns]

Atcer2018... I replaced the injector and spark plugs along with all fuel injectors hoping all the codes went away.

 

[Atcer2018]

Any chance you can switch the #7 injector with a different cylinder to eliminate the possibility of a faulty injector? Big PITA but it would remove that possibility.