Nope, it was set correctly to volts. I checked it again today just like before. I put the red voltmeter lead on the large lug on the lower back of the alternator and the black lead went to ground. Had 32.5 V there.

The other end of that lug on the alternator feeds into the bus on the driver's side firewall where all the relays are via a large black cable and is next to the red lead from the (+) terminal of the battery. I measured it at that bus and it also showed 32.5 V.

Battery itself still showing 12.2 volts at idle, 12.78 with engine off.

 

Well let's hope your Dodge dealer can figure this one out. Good luck and let us know what happens.

JImmy

 

Here's a couple pics of the relay bus with the cover off. The cable on the right connects to the back of the alternator and is running 32-33 V. (That alternator (out of the vehicle) tested good at two different auto parts stores yesterday.)

The cable on the left (red) connects to the positive battery terminal. You will see that the fuse/link between those two lugs (green cover removed) has burnt out. The cover rates that link at 40A/32V.

Relay_2.jpg
Relay_1.jpg

 

Soemthing is definitely going on with your electrical system. Something has to be seriously wrong somewhere to pop a 40 amp main fuse like that. What happens when you replace the fuse? That fuse link looks like it has been replaced before because the screws look like they have been removed and reinstalled. Makes me wonder if the mechanic who did the fuel pump either did some kind of damage he didn't tell you about or he had some other problem he didn't tell you about. The truck was running fine before the fuel pump failed. I can not see how replacing a fuel pump could cause these alternator and PCM problems. I replaced my own fuel pump back in February and didn't have any electrical problems. Lots of others here have also done their own fuel pumps and not had any electrical problems.

When you replaced the alternator did you not disconnect the negative battery terminal before you replaced the alternator? If the fuse blows again when you replace it, either there is a short in the cable between the alternator and battery positive connector at the Power Distribution Center, or there is an internal problem with the alternator, very unlikely since it tested OK, or you still have a problem with the voltage regulator and/or PCM. If you still have PCM problems, there has to be something in the truck causing the PCM to fail. It's very unlikely that you would get 3 bad PCM's in a row. The PCM rebuilder in Florida does have a very good reputation for quality parts. I do hope I never have to find out for myself though.

I have a 2001 Dakota and my electrical system is a little different from yours, but I checked my own alternator with my volt meter this afternoon. With the truck idling in my garage I had 13.84 volts across the battery terminals and I had 13.85 volts on the positive output terminal on the back of my alternator.

I hope the Dodge dealer can figure this thing out for you. Please post back when you know something. I have never seen or heard of this kind of electrical problem on any vehicle, Dodge or otherwise before. I'd like to know what the solution is on this.

Jimmy

 

Yeah, the link looked a little weird to me too, and I'm beginning to wonder the same thing re. the mechanic. It was just fine before the fuel pump, then once he replaced that, he had the "no fire at the plugs" condition, etc.

I removed both cables for everything I've done thus far. It's getting to the point where I unhook the battery to open the door.

I was going to replace that fusible link but the parts store didn't have it. I wonder if that's the whole thing or if the PCM isn't getting a field strength reading and is interpreting that as a need for more juice?

Regardless, it'll be in the shop when it opens tomorrow. I'm out of patience, ideas, and bus tokens, in that order.

Thanks again for all the good advice.

 

The truck is fixed and running fine. I'd like to say it was some esoteric never-in-a-million-years oddball solution, but it wasn't.

As it turns out, if you flip the top cover of the PDC over, it says "140A from alternator." Not 40A. 140A. That bit of knowledge cost me $53 bucks of shop time, which I was happy to pay.

I think I know now what happened. Fuel pump died, had it towed to mechanic 1 who was ASE certified, but it was a tire shop, after all. Guy had lots of 'internet street cred'.

He dicks around putting the new fuel pump in and pops the PCM and the alternator relay and doesn't 'carry the right one', so slaps a 40A relay in there instead, adds the new PCM, engine starts, my debit card clears, and I'm somebody else's problem.

His fault, yes, but mine for not doing the simplest thing of all: turning the cover over and seeing that the relay was 100A shy of the requirement and jumped in with all manner of electrical tests.

I am profoundly sorry for having wasted everyone's time. In my defense, one mechanic either missed it or ignored it, or flat-out did it wrong, and the guy who tested the alternator at OReilly stood right there looking at the wrong relay, never said a word except "that's probably a dealer part."

Mechanic 2 fixed it, wasn't unreasonable and had the courtesy to not laugh in my face.

Output voltage at B+ is 14-ish, battery at idle is the same and gauge reads just right on 14.

I kinda doubt now that the old PCM was bad, I think he fried it when he was screwing around with the fuel pump. Never be able to prove it, though.

 

Well I am glad to know it's finally fixed. I would hate to know how much money this whole ordeal cost you. And you are right, there is no way in the world you could prove that mechanic #1 caused all the problems with your truck. I think you are also dead on with your ideas about what really happened. You would never be able to prove it though, and the mechanic would probably never own up to it anyway.

Stories like this are the reason why I absolutely do not trust dealers, independent shops, mechanics, or anyone else to work on my truck. Plus I have a real problem with paying someone to do something I can do or learn how to do for myself.

It's good to know the truck is fixed and running right. And you didn't waste anyone's time here. Those of us here on this forum help each other solve problems, save money and keep our trucks running the best we can. I really enjoy pitching in and helping out when someone posts about a problem that I am familiar with or may have seen before. One day sooner or later I might be in your shoes and I know someone here will probably be able to help me out if and when I have a problem with my own Dakota.

Jimmy

 

I think, all told, my *little* $400 dollar fuel pump replacement turned out at about $1100 bucks.

I do appreciate the help. It's run like a top all week long. Looks like I'll have it in tip-top shape just about the time my kid turns 16 and needs a vehicle...