Engine/Transmission (1994 - 1998) '96 charging system problems

[Rescue Ram]

Electrical guru's,

My '96 has developed a new and concerning problem. At engine speeds above 1500 rpm or so and at normal operating temperature, the lights develop a flickering. I first noticed the flickering in January on the way back from Florida. The headlights seemed to flicker for a few seconds, and then return to normal intensity. This only occurred once during that trip. During the recent cold snap here, I have noticed the flickering regularly. The flickering can be observed in the panel lights, 4wd indicator light and interior lights while sitting on fire calls with the high idler engaged, and in the headlights while driving. The flickering seems to be more related to engine speed than electrical demand. I have noticed the flickering during the daytime in the 4wd light with no electrical demand, and at night with all emergency lights and headlights on. There is no noticeable guage fluctuation with the flickering. However, the truck has shown a consistent 14 volts on the gauge since new; it now shows between 16 - 17 volts. Also, on cold starts the gauge seems to dip lower than usual when cycling the grid heaters. I am currently running optima red tops that are around 3 years old.



My theories:



1. A failing or failed voltage regulator causing an overcharge condition. I had a similar problem on a gas Ford pickup. Shortly after the flickering started, the battery boiled over and took most of the electrical system with it. I believe the voltage regulator is a function of the PCM on this truck.



2. The alternator is giving death signals.



3. One of the batteries is weak, causing unusual demands on the charging system.



4. A faulty ground strap or grounding problem.



Any ideas, suggestions or insights would be invaluable. I really don't wish a repeat of the troubles I had with that Ford.

Thanks in advance,

Brian Z. Oo.

 

[bmoeller]

Good theories.



The PCM regulates the voltage. Not an internal or some other external regulator.



Are your battery terminals clean?

 

[Rescue Ram]

That is a good question. I checked all of the terminals, and they are clean; all cables are tight. It gave me another idea, though.



All of my emergency equipment gets power from the hot side of the power distribution center on the driver side wheel well. The power is routed through a 50 amp breaker, and then to separate relays and fuses for each component. All of my radios (3) and my running board lights are wired directly to the hot side of the driver side battery.



While in Florida, I installed (2) 100 watt driving lights in place of the OEM fog lights. I used a new switch and fused them in-line. They, too, are connected to the driver side battery.



Is it somehow possible, that by drawing so much amperage off of one battery, that I have somehow thrown the charging system off balance. Does the PCM have a mechanism for monitoring charge on the batteries separately, and it is somehow trying to compensate for the excessive draw on one battery?



I don't think there is much to this idea, since I have seen the flickering during the day with no accessories on. But, a little rewiring would be the cheapest and easiest fix I can think of...



Any ideas, suggestions or insights would be invaluable.

Thanks

Brian Z. Oo.

 

[Rescue Ram]

Any Input?

Anyone experienced with auto electrics, I would appreciate some guidance...



Both batteries have load tested O. K. All terminals are clean and secure, as is the system ground. The symptoms are still the same.



Has anyone encountered a similar type of problem on this Dodge system?



I am still leaning toward a faulty alternator or PCM, but not sure. I don't have access to a scan tool, so it is at a Dodge shop here in town. The tech wanted to blame my after market equipment right away; but I am not willing to buy into that yet. Any ideas or suggestions would be appreciated, as always.



Also, a question:



I was told once by a Dodge technician that my high amp draw items (light bar, etc) should be connected at the power distribution center. They are. However, the tech today told me that this is a major NO NO by DC standards, and that they should be connected directly to the battery. Any opinions, or an idea where I could find this in writing?



Thanks in advance,

Brian Z Oo.

 

[SMorneau]

maybe it has something to do with the temp sensor in the battery tray?

 

[Andy Redmond]

Are you taxing the 120-130 amp alt. ? Have you calculated the amps used by each of your accessories? Is your cable heavy enough to carry the amps without voltage drop? (bigger wire to carry the load farther to prevent voltage drops on long runs, particularly these "high drain" items you mention)?



You mentioned the new 100 watt lamps on a switch, you are toggling a relay with the switch rather than allowing the switch to carry the load of the new fogs. .



Also you mentioned it happened after the fog lamps. . backtrack. . I bet you find your problem.



Good luck

Andy

 

[cartman]

hi ram first all of your lights and any of you after market equipment should be connected at the battery and of corse then fused from there, if you connect into the fuse box the computor will detect the exter currenr draw and that could cause some real problems even more so with newer trucks. now for the problem your haveing disconect all your your extra equipment and see if you still have the same problem if not well its some thing you have extra there then you have to check all you lights ect. if the problem is still there then disconect the altornater and tape up any losse wires check agine for your problem if its not there something wrong with the alt, rember the lights wont be as bright but your just checking to see if the lights flicker, if they do you may have a bad battery or bad connection some were write back to let us know what you find good luck take care

 

[Rescue Ram]

Thanks for the help...

Morning

I just got the diagnosis today. After following my gut, and all of your suggestions, we have narrowed the problem down to the PCM. Every other component of the charging system is operating within specifications. So... the $560 +/- for a new pcm is still cheaper than a new truck. Hopefully this solves all the charging system problems. The new part won't be available until the second week of March; that doesn't help my cause much, but such is life. Thanks for all the suggestions and guidance. I'll update after the new PCM is in.



Brian Z. Oo.

 

[K5IP]

Hi,

The batteries are wired in parallel, an look like one hugh battery to the charging system. They are charged as one unit. If your charging system is really charging to 16 or 17 VDC, this is too high. Verify with a good digital voltmeter. 14. 75 @75deg F to a fully charged battery with the engine running at 1500 rpm is a good number.

Excessive charging voltage will shorten battery life and may quickly damage other systems... . radio etc.

Sounds like a PCM to me.

Rog

 

[HoleshotHolset]

Wouldn't worn brushes inside the alternator cause flickering/funky charging as well?



If the brushes are worn - then the voltage they are transferring is going to be whacky as well.



Matt

 

[Rescue Ram]

HoleshotHolset wrote:

Wouldn't worn brushes inside the alternator cause flickering/funky charging as well?

Yes, it would. I still am convinced of an intermintent PCM problem. This morning, we were initially unable to duplicate the condition. All of a sudden, the digital voltmeter started registering large fluctuations in voltage, cycling from 12 volts to as high as 15. 5 volts. After a few seconds of that crap, it seemed to stick in a wide open overcharge condition. The meter registered a constant 16. 8 volts.



That is where I stand at the moment. Hopefully the PCM replacement will fix it.



Brian Z Oo.

 

[K5IP]

Keep an eye on the voltage if you keep running your truck. 16. 7 is really high and if your charging system has gone "open loop"

the only thing limiting the max voltage is the battery. As the battery becomes even more overcharged this voltage will continue to increase. Bad brushes can cause the flicker but not the excessive charge you now have. I think your diagnosis is correct, but did the service tech consider the temp sensor located near the battery commpartment. It does provide one input to the PCM for battery charging?

Rog

 

[Rescue Ram]

Fortunately, I have another truck to use while this one is down. I don't want to run the risk of cooking the entire electrical system running with a constant overcharge. I tried that once... Not too much fun when the batter boiled over and killed just about every fuse...



About the battery tray temp sensor... Is this the same temp sensor that controls/ provides input for the heat grids? We did not talk about it specifically, but it might be a good avenue to consider.



On batteries... The tech discouraged the use of Optima dry cell batteries. He claims to have seen odd electrical behavior in vehicles; supposedly caused by these batteries. I received a similar warning from a VW tech and at an unaffiliated Dodge service department. In all cases, they advocated the use of a conventional battery, but not specifically theirs. Anyone want to weigh in on this? I have used Optima batteries for years with only one bad experience; I had two batteries fail suddenly in my GM 6. 5L when they were very new.



Thanks again for all the advice, input and suggestions.



Brian Z Oo.

 

[K5IP]

Brian,

About the sensor, I just don't know, but it is worth checking out. I am presently spending my winter in Hawaii and do not have my service manual with me. I do think it is a good idea to use another truck until you get it fixed.

The Optima batteries (red, or blue) do have slightly different charge/discharge criteria. The difference is, small enough so that they work well even with charging systems designed for lead-acid wet cell systems. Guess I would not worry about that, but I would hate to ruin them by over charging. In a lead acid battery you boil the water away, and they can take it, up to a point, but in the Optima, I don't know what the limits are.

Good luck.

Rog

 

[Monroefiredog1]

Alternator

Hello Rescue Ram,



I have a 96 and i just went thru the same problem, I checked for everything and even replace the Crank Postion Sensor, which did not help. I had my alternator checked by Autozone, both on the truck and on the bench, and they said that it was fine. So I was chasing something else, Then I finially took the Alt off again and took it to Southern Auto Eletric and they said that the brushes were gone. They replaced the brushes and now all is fine. Just make sure that the alternator is goo, from someone that is reliable, not Auto Zone.



Good Luck



D. L. Brookshire

 

[HoleshotHolset]

"They replaced the brushes and now all is fine. "



There's one more supporter of my theory...



Dad's truck did something similar to this whole scenario, but his alternator was just lazy... . it would take a while before it would get a good charge going. He swapped it out with a reman and hasn't looked back.



The previous owner of my truck had an OEM battery explode on the passenger side. He said it sounded like a 12-gauge going off. My old boss' '98 1500 did the same thing with the OEM batteries.



I've never heard of anyone having issues with Optimas... . I sure as heck never had any problems with the 'redtop' Optima in my old S10.



Matt

 

[Rescue Ram]

Hmmm...



Does anyone know about the battery temp tray sensor that has been mentioned in this thread? Is it the same temp sensor that regulates the operation of the heat grids? I have seen some odd operation of the heat grids. Mainly, on restarting a fully warm engine, the heat grids will cycle for a full cycle. It does not occur often, but it seems to be associated with the charging system problem. That would indicate a PCM problem to me. Who knows... Hearing about all these funky alternators makes me nervous. I would sure hate to buy an unneeded PCM. On the other hand, I would have a spare on hand for 40 years down the road when they're not available anymore.



Thanks for all the ideas and suggestions.



Brian ZOo.

 

[HoleshotHolset]

I believe the grid heaters are triggered by either IAT or coolant temp... . not battery temp.



Buy a reman alternator... . I'd rather have a spare alternator than a spare $$$ PCM.



Matt

 

[cartman]

there is a temp sensor in the intake manifold for the heater grid

 

[K5IP]

Brian,

still thinking about your problem.

If, in fact the PCM is at fault. I wonder if you could not simply install an aftermarket voltage regulator into the system. Some ingenuity/wiring would be required, but all a voltage regulator does to control the output of the alternator is limit the current to the field winding (through the brushes). Probably just one wire to swap.

If other functions of the PCM (cruise control, tach,engine shut down and grid heaters) still function normally I would give it a try.

Still wonder though. Electronics are not usually intermittant. Either good or bad so check for poor connections too.

Rog