Electrical problems, biggest is alternator

[raxley]

I'm pretty bad at diagnosing.
I thought I had a bad alternator, and I replaced it to find it still won't charge, and my gauge on dash (that and fuel gauge are about only working gauges) shows it too.

I don't know where to start. Circuits that control my AC blower, some gauges, power windows and starter don't work. I'm quite a ways out from town, beautiful, but no gas station on corner.

How do I check and see if it's the ECM? What is the procedure is the ECM is bad? I know that there will have to be a regulator, what other critical things does the ECM do?

I don't think it is related, but it might be. When I'm driving around, my power is WAY down. I can't go very fast either because I suppose the lock up converter needs power, and evidently isn't getting it. The circuit that is affected also is the blower motor, the power windows, speedo, and tach. I had the power problem a couple of months ago, I thought it was fixed, although the guy said I need a different spring or something in my AFC (don't know if name is right, but it's the thing on top of the p7100.
With the charging 'out', my truck has some crippling properties, and I need them fixed. Rather not spend the money, but can't 'economize' here if it means no transportation.
Really need a auto electric guy that's somewhere around Sacramento. Actually, could be a little further- as long as I can leave the truck running, it doesn't use much electricity. Obviously, I can't drive at night, but I've been in Placerville 6 hours driving around and even turned the beast off once (when I replaced the alternator). It started right up, after.

 

[GAmes]

Is the tach working? BTW, a 12 valve doesn't have an ECM. Did you swap the PCM and harness from the donor truck or wire in the 2005 system?

 

[raxley]

No, the tach and speedo do not work since my electrical problem. As far as I know (pretty sure) that my 1994 is completely stock. I guess I just don't know what is IN it! I thought it had some type of minor computer that took care of the voltage regulator, which is why, when it goes out, you have to have a different arrangement along with a voltage regulator for the alternator.

 

[GAmes]

The voltage regulator in a 2nd gen is in the PCM. If you don't have a PCM an external voltage regulator is required. How long ago was the 12 valve installed in the '05? Or is that what you have? Your signature is confusing.

 

[raxley]

I'm sorry about the 'signature'.
This post has NOTHING to do with my signature.
It's a stock 1994 Dodge 2500 w/ diesel. I did put p7100 gov. springs in, and upgraded valve springs to the 60# PacBrake springs, and a BHAF.
I AM getting another alternator (a 240 amp, instead of 120 amp) but since my (new) STOCK 120 amp alternator isn't working, I'm asking for help in getting it FIXED.
Don't ask me to do any (more) diagnostics! Almost certain that if I come up with a DX, it WON'T be correct!
I replaced ignition switch a couple of days ago and NOW alternator.
It got a LITTLE better when I tightened up a starter bolt, which made it harder for starter to turn over.

How do I check PCM? And if it IS that, how do I put external regulator on? Are there places that sell the modification? What ELSE does PCM do, that I will ALSO need to fix?

The 2005 is pretty much history. I pulled engine and trans and I am going to turn the body into a trailer. People will WONDER where I got a trailer that is in SUCH good shape. Great paint and not a 'ding' anywhere!

I have a DVD with the 1994 shop manual on it (I'll pick it up today) and I have a regular test light and a new one that inputs voltage and does all kinds of stuff. Amazon product ASIN B071LHLSBBI have other multi meters,etc. but I lack the knowledge to really use them.
I need to trace a circuit.

 

[GAmes]

The different functions (input and output) of the PCM are listed in the FSM. Installing an external voltage regulator is simple, but since none of you gauges are working you have a lot more issues that a VR won't fix. Most of the things you list that don't work have nothing to do with the PCM (windows, AC fan, etc). The first thing I recommend is to locate and clean all the grounds on the body and engine. There is an illustration in the FSM that shows them. Clean up the battery terminals and check for corroded wires and battery clamps. Verify your batteries are serviceable. Once that is done you will be able to troubleshoot more effectively.

 

[BigPapa]

I would begin by checking the ESS (Engine Speed Sensor). Check the connector and all related wiring. The ESS sends the engine RPM to the PCM. If it is not functioning, the PCM doesn't "know" the engine is running which means it won't make the alternator charge, the tach won't work, and the A/C won't work.

 

[raxley]

Thanks for your reply. I put a bigger fuse in for the starter, AC blower and it's working now. I blew an earlier one, a 40 amp (have 60 in now) I can see the tach working now, and yesterday had the blower and window working. Hopefully, when I drive away, the speedo will work too.
Although it's inconvenient to have those out, the BIG problem is charging. I can live with the rest (for the moment)
I need to eliminate the ECM from my charging mishaps, or I need to be making plans to have a external regulator put on. I have to get charging back. Right now I carry a generator, and 2 battery chargers, as well as other tools.
I can go all day (without headlights) if I don't have to start. Yesterday, I even turned it off, and restarted later. I got home and batteries showed about 12.2 volts.

 

[raxley]

Wow.
My meter shows it's getting 13.8 volts now. My gauge on dash shows ok.
I've got a 60 amp fuse in the "40 amp ignition run/acc."
I thought the only thing keeping it charging was the big 120 amp for the whole thing. As long as that wasn't blown, I thought it would HAVE to charge.
I guess I don't know much here.
But I'll 'take' the charging right now, and see what happens today.
It was really keeping me from doing anything else, and I'm not good at auto stuff anyway (esp. diagnosis)
I will post at end of day if it's still working.

 

[GAmes]

Just the fact that you felt forced to go to bigger fuses is troubling. You really need to find and fix your base faults to get a handle on the charging issue. Those bigger fuses present a fire danger. Do you read the other threads that touch on your problems like this one https://www.turbodieselregister.com/threads/speedometer-died.271850/ ? BigPapa pointed out information that has been covered dozens of times. Search is your friend. Regardless, if you plan on doing the repairs yourself you will need to learn to read wire diagrams and learn how to operate a multimeter.

 

[raxley]

I wonder if I damaged the ? bendix? Is that the thing that shoots out and engages the starter ring on the flex plate? I noticed that the upper bolt holding my starter in was loose. When I tightened it up, much of my problems went away. I still think the starter is having a harder time turning over than in past.
The starter SHOULD be in great shape. It was only a couple of years ago that I replaced everything that could be replaced with FosterTruck parts, about $200. Contacts, brushes, and the big 'armature' (not sure that's the name for it, maybe it's something else)
Right now, I have an 'accommodation' with the truck. I climb under to jump the starter (about a 2" long solid copper wire) and everything else works. I currently have a 20 amp fuse in the 40 amp socket, and I'm careful not to use the blower motor (seems most power hungry after starter) unless it's the only thing running. I've started the truck a couple of times when I forgot it's got a 'problem', I just got in an turned the key. But lately it just 'clicks', and the 'extra' wire that goes to starter selenoid, it sometimes doesn't let enough electricity through, and will barely turn over or just click. The only way it's 'reliable' is the 2" long jumper, that has always worked. The weather has something to do with it too, it seems to work better when weather is dry.
Another strange thing, a couple of days ago, I didn't have an alternator. I replaced it and it STILL didn't work. I finally replaced the fuse (40 amp one I've been discussing) and I got the alternator back. I thought that was funny, that the alternator was fused in two places (the 125 amp fuse where power first comes in), and then when I blew the fuse, I still had the alternator.
I received my 240 amp alternator, although I haven't put it in yet. Won't I need to replace that 120 amp fuse with a 240 amp one?

 

[raxley]

I got my 1994 cd with the wiring diagram. I need to learn how to trace a circuit. Anybody know of a 101 or beginners site? Surely it must be on youtube!
Thanks for the help and feedback!