Why is my charging system is not working? How can I fix it?

so what is actually happening? if the battery is good and the alternator is charging, then everything is working. Is the battery dying over night or something?

The alternator is not charging

I replaced it. And the battery

The voltage meter reads 12ish. I've researched this problem and it sounds like it's the voltage regulator, inside the pcm. So I replaced the pcm. Yet it still didn't fix the issue

Take the alternator out and have it bench tested. This takes the Pcm voltage regulator out of the equation. It is possible that your new alternator is bad. Have had that happen to me. Also, make sure all wiring is good especially from the pcm to the alternator. There may be a way to test the pcm voltage regulator, that would be ideal, but it may require sophisticated testing equipment.

Have the battery charged and load tested. It could also be bad.

check your 140 amp charging system fuse under the hood.

I am having the exact same issue with my truck. New Alt, a new battery which tests good, PCM fuse #23 is good, and I bypassed the fusible link from the alt to battery and it is still not charging. I have not replaced the PCM yet. When I start my truck my alternator shows it is charging on the gauge at idle but as soon as I put it under a load by driving or by turning on lights, heater, radio, etc it goes to 0 and my check gauges light comes on. I am concerned it is a ground, the PCM, or a battery temp sensor issue but I would like to know how your issue turned out before I buy a new PCM.

Soaleman- I am having the same issue. How did you fix it?

I am also have the same issue with my 03 Dodge ram 2500 with a 5.7L battery is good and a brand new alt. I turn the accessories on and the gauge shows voltage. I start the truck it looks like it's going to work then it drops to zero and says check gauges. What is the problem.

I actually bypassed the PCM with an external voltage regulator from a 70s dodge truck and it works great. $35 bucks for the parts and about a hour to set up. Plus you can always put it back to stock later. The PCM was bad and it was telling the alt to stop when it went under a load. I talked to a guy who sells PCMs and he said the diode went out.

Yep that's what I did, and it still didn't charge. So I actually took the alternator off and had it bench tested. Failed. Got a new alternator and external voltage regulator works. Getting a new PCM now though because of some old connectors that have corroded.... Mud is fun for 5 mins but it is probably the worst thing you can do to your rig hahah!

When I jump it off the check gauge come on

Replace the black cable that runs from alternator to fuse box under hood

Engine cranks but won’t start the starter works but no fuel pressure. The the battery dies and I load tested it and it was gone and it was fully charged.

I have same problem no luck still no charge.alt good.but external votige no charge good battery cable to missing something

My 97 Ram 1500 5.9, charges sometimes and sometimes not. Alternator tested good on truck and on test bench. Replaced PCM, no change. Fuse is good and all connections look good and have been disconnected and reconnected. Still part time charging, charges correctly when charging, no charge at all when not. Battery tests good and thank goodness runs truck when charging stops. No consistency to when it does or doesn't. Help please.

Just me again on my 1997 Dodge Ram 1500 part time alternator that tests good on the bench. I have been advised that a failing alternator will often test good on the test machine because it does not present the alternator with a true field load condition and will often test good, but fail under normal vehicle loads. What say any of you about this?

This is sometimes correct, an Alternator “ Bench Test” is a good preliminary Test, but is not 100%, as under Driving where multiple Loads are Multiplied, reduced, low, change frequently, per System demand . You can improve reliability on a Bench Test by bringing a Hair Dryer with you, hitting the

- Continued, hitting the Alternator with Heat simulates Engine Heat- some Components fail or become less effective when Heat is induced, such as Ignition Systems Components “Bench Tested”. Clamp forces are not identical when on a Bench vs. installed in a specific engine. In the Motor it may be slightly misaligned at Bolt points, causing Housing Torque creating internal clearance difference- moreso with internal expansion, e.g.; Resin worn off a Winding, the above Physics causing Case contact while I installed, etc. Hope that helps, some!

My 2005 Dodge Van with 100K miles has varying charging voltage (around 13.6v to 14.8v that is intermittent -- when not varying it sets at about 13.8v). First noticed when driving at night and saw head lights and dash lights modulating. Then looked at VM plugged it in a cig lighter and saw the variation in voltage. See the variation in voltage in day time also -- again it is intermittent (sometimes see normal steady about 13.8V). Have not trouble shot it yet, but at present I suspect the PCM (computer). Like idea of installing a separate regulator to bypass PCM control of the voltage output. .

Has anyone had this issue and found a solid fix? Having the same issues on my 2005 5.7 Ram 1500, but it seems like all the Q&A's ive seen have no firm answer. My trucks voltage will read low cold starting, and then drop to zero while running. After running it for approx 20 mins, I will restart the truck and the voltage will have the correct reading again. I replaced the alternator and battery because they coincidentally tested bad, no change. Any help/advice regarding the issue would be greatly appreciated. Thank you in advance.

Before replacing anything , READ THIS !!! I literally just came to this sight this morning looking for answers, all helpful, but then thought oh boy, here we go, chasing a ghost!! So anyhow, my van, has new battery, started discharging a few days ago !! After reading all the great potential problems, I had to run to the store ! On my way back home, stopped at red light revved van to keep it at least 12 bolts by the dash gauge, I noticed the needle tried to jump, so I mashed the pedal, heard a click, then all of the sudden the gauge jumped to 14 volts! Evidently that must have triggered the PCU or regulator to start working, I then turned everything electric on and revved it again , and it stayed at 14 volts!!! I first had an issue before with alarm system, because when I bought the van not long ago, it had crappy cable ends! I had no idea until I had to get a jump a couple days ago!! I put the new ends on, and charged the battery! No luck, so if you have an alarm system, that may make it act up, if you've had a dead battery, regardless, rev it up and see if it fixes it

Okay, 2001 Dodge Ram 1500 v8 5.9l Fixed. I had intermittent charging problems, and sometimes no start. Batter tested good, charger tested good, but once in a while it wouldn't start or would ramp up the voltage until it was over 18 volts. This was because when a battery is disconnected, the alternator will take over and supply too much voltage, also, its old. Now, for me, it was two things causing the alternator to think the truck had no battery. 1. We had just replaced the water pump, and had put the ground back on one of its bolts, a large main ground, and it was gunky and filthy and oil, which gave it horrible grounding and connection. I checked other grounds and cleaned them that were near the battery, my headlights were grounded to freaking paint! No wonder they were dim! Two, My little screws that clamp the battery wires to the big clamps before those themselves clamp onto the posts were loose. And the wires were corroded, which gave them less connection, and because a tug here or there, or sway or bump could wiggle what little connection was left off of it, the alternator had so little battery voltage that it simply took over and went crazy with the over voltage. So I cleaned my grounds, snipped my battery wires back 1/2 an inch , cleaned up connection areas on my clamps, put the fresh wires in the cleaned clamps and tightened them down to get the most contact, then cleaned the big part of the clamp to the posts, and the posts, and put it together, positive first, negative second. Always blow across the battery a few times before connecting the last post, to get any hydrogen away from it that might be lingering and blow up in your face. The truck started. It ran smooth. It even went back to low rpms like normal, and was saving gas again. I was told that sometimes the positive wire at the alternator needs cleaned too, and starter. But I only cleaned my positive wire, and re-stripped it, at the battery itself. Good luck, I hope this helps. PS. I had also gotten weird codes on the dash during these events, one was pdone or pd one. It's not throwing that speedometer mileage code anymore.

What is this where can I find it

05 Ram 4.7 and I've had low voltage for about a year. Replaced alternator, battery, and alternator to fuse box cable. Still no luck. On damp days voltage would be ok, warmer days it would be below a half gauge. Read through posts and came across the "battery temperature sensor". It sits below the battery and in warmer weather throttles the voltage back, colder weather it bumps it up. Its what triggers the alternator to charge. Replaced it and so far my gauge has consistently been above half since. It wasn't bad or else it would've triggered a code but, was going bad.

test large red battery power wire for 12 volts at alternator,check both small wires from alternator to power train control module for a short to power or ground and check for high resistance on the same 2 wires they should not be over 2 ohms from pcm to alternator if alternator test good on bench it sounds like a internal pcm regulator

The guy who stumped on the gas pedal at a red light accidentally ( Reset his PCM !!!!! ) thats just 1 of the pcm reset procedures . Seven to ten seconds hold down. The accelerator . look it up .

same issues on 2009 ram multiple new alternators 2 new batteries and new pcm. still not charging. any new thoughts or fixes on this common problem?

I am having simular issue 98 ram 1500 5.2 have put 2 new alternators in I have to jump it off and as soon as I take cables off it instantly dies while it is running tho sometimes the dash gauges work sometimes they dont gauge light sometimes come on and sometimes doesnt can not figure out what is wrong alt is good

Please help asap if any knowledge of what is wrong as this is my daily driver

This is our daily driver also. Just happened to us. Stomped on the gas to leave after getting gas and everything shut down. Replaced alternator and gobs of sensors. Did we reset our pcm on accident? How do we correct this.

To add we disconnected the new alternator to see if it would continue to blow the fuse. It worked, truck started right up and no blown fused. We have a trash alternator. Possibly the short is within the new one .Will change out tomorrow and see how it does.

I got a 2002 dodge 5.9 360 slt 4×4 changed the fuel pump, muffler, throttle positioning sensor map sensor distributer cap wires plugs battery. Now thinking it was going to be a great truck i have to charge the battery to start it when I shut it off the battery just dies . Or it will aCT up when driving it and shut off. Could it possibly be the alternater, or bad ground?

stuartawm where did you get ur pcm from

i have an 05 ram 1500 big horn. truck dies once in a while especially after disconnecting and reconnecting the old battery. just replaced the battery, egr valve, cleaned the iat and throttle body. fuses are good, theres no dash maint lights and the scanner shows no codes. its died 3 times today, but we cant figure out why... any advice would be great.

If there is an oxide build-up on the battery connectors, or posts, that consitutes a chemical Diode, allowing current to flow in only one direction. The battery will easliy discharge, but not charge. Clean the connection wires at the clamps, and scrape down to fresh lead on the posts & inside the connector clamp receptacles. Coat it all with some vaseline, to keep it from corroding, and if necessary, wash the posts & top of the battery with water & baking soda to neutralize any acid spillage.