In most cars I have had, somewhere north of 14 volts is where they charge at. My Ram is charging around 13.6v, and when I hit the AC it drops to 12 or so. It's also trying so hard it makes the belt squeal. When sitting with the truck off its sitting around 12.7v and I believe that to be normal'ish.

To get by until I can afford an alternator (which I believe to be the problem) I unplugged my daytime running light module which is a big help...

Any other suggestions? Any other commonly known issues? Like maybe a

• commonly bad ground?
• commonly bad plug on the alternator?
• Something else that I can't find with the search function?

Thanks in advance!

 

Optimum charging for the battery is 13.6 volts according to my snap on scanner. The gauge in the cluster is very misleading if that is what you are going by.

I'd try to pin down the source of belt squeal, usually a bit of WD-40 on the offending pulley while the vehicle is running makes the squeak go away and you know which one you're dealing with. Wait about 20 seconds between pulleys to allow the lubricant to penetrate.

 

Nope checked it with a DVM (Digital Volt Meter)

It is for sure 100% the alternator pully. The alternator senses the demand and makes it work harder.

I guess this is a belt/tension issue.

 

IT may be the bearing on the end shaft of the ALT vs. the actual pulley assembly.


One problem that can arise is there's a regulator CKT at the PCM level which, if that's starting to go (component value / tolerance drift etc) it will go out eventually thus requiring a new PCM.


But, sure, with absolute certainty, all the items you've mentioned could also be probable root cause for a low-charge / low-voltage condition.


The real question is: what's the voltage output PRE and POST regulator? That's what you need to ask / find out. <IF> the ALT is putting out 14-16 V PRE regulator, chances are, it's fine. The problem of rooting out the voltage POST regulator is just as you had already performed, testing at the BAT level is a good enough method as any to measure the output POST regulator.


Now that you've already performed that, we know it measured to OEM spec @ 13.6 and, there's a tolerance on that as well due to thermal loading so, it's looking good there. If the ALT wasn't putting out, you wouldn't even see that POST regulator so, that leads me to believe that there may not be an issue with the charging system per say but rather, a load down condition where, it was noted that at time of initiating the A/C, the output voltage dropped to 12 V.


Either that's two things:


* -the IAC motor is not working properly thus not adjusting during load down conditions when the A/C is engaged or,




- ALT is not keeping up with the demand under loading to which, a test should be run on just the ALT out of the vehicle to determine if this is the case or not.


* So, the question is: do the RPM speeds drop when the A/C is engaged?




CM

 

This is one of my worries. Gonna have to pull the belt tomorrow

I am almost wondering if its good insurance to hook uo and older style regulator like in my old Ramcharger? If this regulator circut goes, will it take the entire PCM with it?


Idle air control I believe is working. I will have to double check this.

Load testing the ALT should not be a problem. We have a good auto electric shop in town...

No. It does not drop, just starts squeeling when revved anything above idle. At idle all you notice is a voltage drop between 11.9 and 12.3 volts. It usually recovers 30 seconds later. If on the highway, it will squeal for 30 seconds and then recover until you drop the revs back to idle. This is what leads me to believe its the tension pulley/belt/alternator bearing.

I will have to do more homework this weekend. I am swamped with other stuff till then.

Thanks for the great reply!
Joe

 

There's a problem there for sure. It's dropping a lot of voltage because, even at idle, you should measure ~14 VDC coming into the BAT so, something is up and, it could be a few things but, I've got a pretty good idea of what the root problem is.


Possible root cause:


- ALT pulley is slipping on the end shaft thus not spinning in sync to the motor thus leading to erratic voltage output and voltage drops. Condition is further worsened when under A/C loading. This would also explain the mechanical squealing. Very indicative of a slipping pulley on the end shaft at the ALT assembly level.


I'm going to stop there because, at this point, it's almost totally clear to me as to what the root problem is in this case. Based on the evidence and mechanical squealing / screeching, I believe that the problem is rooted in the pulley to end shaft assembly at the ALT thus leading to the end shaft slipping inside the pulley thus the squealing noise and the voltage drop at it's output.


I was going to mention the voltage regulator failing or being faulty. To answer your question, YES< you can use an external regulator in a pinch. However, let's not even go there at this point as that's a whole other topic / workaround to deal with.


Let's just focus on that squealing end shaft to pulley assembly. I would remove the ALT from the vehicle and put it on the bench and inspect the end shaft to pulley interface. Some had a key that locked the pulley to the end shaft while others were a taper fit while some are press-fit.


Remove the end nut and pull the pulley. Inspect the shaft and let's see if we see evidence of a slipping end shaft. There may even be metal shards and galling present.


If it's not at that level, probe one level deeper into the main bearing that keeps the end shafts concentric to one another end during rotation. If it's in the ALT - you'll find it quickly.


CM

 

Mine showed around 13.5v on my volt meter before I upgraded the wiring.

I upgraded the following wires.
- Alternator to power terminal (2AWG) w/ fuse
- Power terminal to battery (2AWG)
- Battery to front bumper ground (4AWG)
- Battery to engine ground (2AWG)
- Battery to core support ground (8AWG)

After those wiring upgrades, my voltage is consistently at 14.2v with my volt meter. That is with the A/C and radio on.

 

All those cable upgrades sound like a good idea. I will keep that in mind for sure.

Pulled the alternator last night and found its a reman unit with a pressed bearing and hub. All tight and good feeling bearings. Same can be said for the idler pully.

Put it back together and I found that the tensioner is almost out of stroke when the belt is on. I need a belt! I sprayed the tensioner spring with penetrating oil and worked it back and forth, put the belt back on and sprayed it with WD40 to get through the night. Just put a new gaterback belt on and we are Good To GO!!!

Headlights, fog lights, off road lights, interior lights, reverse lights, AC, Stereo, cargo light all on and still pulling 13.7 with no slipping.

Thanks for all the helpful replies!
Joe

 

So, it was a slipping belt vs. a slipping pulley at the alternator. Either way, that'll do it- loss of voltage there due to the ALT not spinning at full rmp 100%.

CM