AllenG

A/c relay is good, checked the blue wire, no power to it. Talked to a local mechanic he seems to think that the pcm is shutting down the a/c relay due to low voltage and if we fix the alternator not charging everything else will start working. I am going to look and verify there is no short anywhere, if I replace the pcm I am going to put a inline fuse on the blue wire the way you showed on a post I read last night. Any other reason there would be no power to the blue wire other than the pcm not sending signal?

Thanks for the replies, IBMobile I did that exact test. No power to the blue wire....... JAG1, I swapped back to the old alternator which was putting out 14v and have the same issue. New alternator or old one makes no difference neither will charge. But neither are getting signal from pcm to charge now.

After a year of slight surging and seeing this from my OBDIIscanner I swapped out my apps. I also have completely re done my fuel lines, draw straw, and swapped to a raptor pump. While I was at it I swapped out my alternator since it looked like the original was on the truck. The truck seems to be running great now with no surging.........but now I have another issue! No signal from pcm to the alternator plug so it’s not charging. The ac clutch is also only engaging now at startup, once it kicks off it will not come back on until the next start up. The old alternator was putting out 14v and the ac was working perfect, tried swapping back to the old alternator and no luck. Put the new one back in again and all is the same. Then tested the plug and it looks like nothing is coming from the pcm to the back of the alternator. Yes I have checked all fuses and relays.......is my pcm bad???? Tested the blue wire on the plug with a test light and now power. But the green wire does light up.......reading the write up from mopar1973man in alternator and pcm protection it sounds like I am going to be replacing the pcm and the old alternator already damaged it. I did find a spot on the wire at the back of the old alternator where it had rubbed through and shorted out on the case. I fixed that before I hooked up the new alternator though. Can the faulty pcm also cause the ac clutch to not cycle except right at start up? If you put your foot on the throttle the ac clutch kicks out sooner and will not come back in.

After a year of slight surging and seeing this from my OBDII scanner I swapped out my apps. I also have completely re done my fuel lines, draw straw, and swapped to a raptor pump. While I was at it I swapped out my alternator since it looked like the original was on the truck. The truck seems to be running great now with no surging.........but now I have another issue! No signal from pcm to the alternator plug so it’s not charging. The ac clutch is also only engaging now at startup, once it kicks off it will not come back on until the next start up. The old alternator was putting out 14v and the ac was working perfect, tried swapping back to the old alternator and no luck. Put the new one back in again and all is the same. Then tested the plug and it looks like nothing is coming from the pcm to the back of the alternator. Yes I have checked all fuses and relays.......is my pcm bad????

May be, I was told the 53 blocks in the 99’s had then too. Tell me if I’m wrong it will just save me time. I ordered a scope last night gonna try that before I pull the cover.

Ok I’ll try that and see if it will work. If not I guess I have a good reason to go fix the killer dowl pin now.

They warrantied the first one last month just off of a picture of the p0216 code, picture of good fuel pressure, and picture of the dash showing the truck at speed and rpms. By the way like I told them this truck has never had any programmer on it. Having a programmer was their only question and said that would void their warranty. Damn I don’t want to pull the front cover.....

So you think another faulty pump? Possibly? Or you still think I’m off a tooth? No address but here is the town they had me send the warranty pump to. Diesel power products is out of Spokane Valley, Washington so they must be getting their pumps re built by someone in Arkansas. You know who that may be? And if they’re in the list?

So even with getting it all lined up right and key way at TDC when I pulled the first bad vp44 then the second warranty one you think I may be off one tooth? That will cause the surge and through the code? Cuz it runs great other than every once in a while it surges. Pumps are coming from diesel power products. You can see on the screen shot where the calc load dropped off sharp about 7 times. I did my best through this entire test to keep my foot steady and constant on the pedal and watch the fuel pressure and rpms when it surged. This was all while I was at highway speeds and fuel pressure stays constant when it surges. I thought maybe the ecm was jacking with fueling on the vp. I don’t know anything about the ecm’s on these trucks.

Fuel pressure is around 13 at highway speeds.

I have a new VP44 second one in a month after getting them to warranty the first one due to surging and a P0216 code. Everything from the fuel tank to the VP44 is new, new in injectors too. Truck is still surging and throwing a P0216 code. I am stariting to think it’s the ecm by past posts.