1998 Dodge 2500 Diesel Electrical Issue

That points toward a phantom short somewhere.

With everything turned OFF check directly at the battery(s) terminals for current flow...it should be NONE to very SMALL (alarm systems are powered ALL the time).

If you measure a LARGE current flow, there's either (a) something ON that shouldn't be or (b) a short somewhere (dome light, etc.).

You should have used that money to pay someone to troubleshoot the problem.

Odds are good that both batteries and alternator don't die at the same time.

One thing we have not determined in our fact gathering!

There are two versions of the 98 Dodge 2500 diesel. The first is the 12 valve with inline pump and the second version in the first version of the 24 valve.

I own both types.

Before we start trying to fix the problem we need to know what version we are working on.point

The ECM on the second type will turn the charging system off if the engine RPM's drop below a certain point. All the gauges stop functioning and the Alt stops charging.

Type 1 or first version has a problem with alternator speed. If the engine idle is set too low the Charging system stops working.

Need more DATA!

More data from an AP, that will never happen!

Disconnect the battery while it's running....does it die....trace the charging circuit back...could be the voltage regulator, some are built in to the alternator....check the load on the battery just sitting there without the engine running....check the voltage at the battery terminals when running...check wiring on the alternator...check fuses....

Well..........................................................unhooking the alternator may not be such a good idea, depending on the electrical system in the vehicle.

On some newer vehicles, disconnecting the alternator can damage the electronics.

I'd check first, if I were the OP.

I'd take it to a mechanic if it were mine, but that's because I'm too old to work on anything that doesn't have breaker points.

If you disconnect the positive post on the battery, while the engine is running, it should continue to run off the alternator voltage....that is if the alternator is working...If the alternator is not working, or just improperly connected, the engine will die......but I'm sure you know this so not sure what you mean by unhooking the alternator...unless you mean the alternator feed to the positive post, and well that would be something new to me....Anyway I would check the alternator output at the battery posts with a multimeter first anyway, if I got no elevated reading(14+v), and I wanted to confirm that the brand new alternator I just bought and installed wasn't working, and that the battery wasn't just low or shorted or something, then I might check it by disconnecting the positive terminal on the battery....now if the engine continued to run I would know that the alternator is putting out voltage, maybe not the full voltage, but at least some.....then I would check the voltage of the battery and possibly the cells in the battery...but it's probably a light bulb shorted in the taillight anyway...

Unless this diesel engine uses a mechanical fuel pump with mechanical injectors. I'll admit this is now an unlikely, arcane configuration but....

I did say to test the battery terminals first while connected with engine running for voltage level....If the voltage is reading 14+, then obviously you don't need to disconnect the battery terminal.... Danged newfangled gizmo's....

Lyn is still right, removing the battery from the circuit runs a real high chance of smoking the electrical system, as does removing any wires that are part of the charging circuit. Some vehicles have a "sensing" wire that reads the voltage somewhere in the wiring harness to account for the voltage drop, and some vehicles actually have a voltage regulator that clamps the voltage around 15V to protect against some idiot CR4 members who still like to lift wires.

The best way to check charging/battery system performance is to buy a cheapie load box. First you put the load on the battery with the key in the off position, then watch how quickly the voltage drops, then you start the engine and watch to see how many volts the alternator puts out under load. Do this every six months and you'll see a trend developing that tells you when the battery is loosing its ability to hold a charge or if its a blown diode, failed regulator, poor connection, etc. that's causing the battery to not receive a full charge.

http://www.aa1car.com/library/battery_runs_down.htm

If it is ever necessary to remove a battery terminal clamp; Be sure that you have the radio code to reset it!

jurie

There are inexpensive adapters that can be plugged into the power (cigarette lighter) socket to prevent loosing codes with the battery disconnected. They consist of a 9 volt battery, socket for this battery, wires and a power plug that is placed into the power socket. To hold the codes requires very little current. Plug this in and work on the battery junction or other device with the battery disconnected. Another way to make one is to go to Radio Shack or other retailer/distributor (no endorsements) and make your own. It is also cheaper and "custom made". Make sure you get the polarities correct.

Good Luck, Old Salt

Thanks Old Salt, I'm going to make such a tool tomorrow to keep with my toolkit!

Wonder if I could still find a simple,pionts and bobbin, voltage regulator as used by the old valliants [+_ 70's] here in SA.

I think it is Radio Shack but I made mine with a commercial power plug and a set of Binding Posts on the other end. One red and one black. Center of power plug goes to the red and the ground goes to the black. I like it because there are many other things I can do with it. Typical is reading alternator/battery voltage while driving, easier than running wires from under the hood. Also easier than trying to run along beside the car and driving at the same time.

Good Luck, Old Salt

Measure battery voltage, start engine, does lights get brighter when engine revs....or voltage is higher say 14V to check if alternator is changing.

On old vehicles that used a generator you could remove the battery cable while the engine was running at a speed a bit higher than idle BUT do not remove battery cables while the engine is running where an alternator is fitted; The voltage output might just be too high and it can blow the alternator diodes.

With engine stopped, remove the earthed battery cable; Measure the voltage between that battery pole and the earth cable. All switches must be in off position, car doors closed etc. and the voltage should not be more than 1V. If higher, remove fuses and relays one by one, checking if the voltage drops to find out which circuit is the culprit as someone already said.

If it gets to the point where you suspect that it is a shorted wire or some other current draw that shouldn't be drawing current, trace it with an amp meter as others have suggested. The problem with though is that you must put this meter in series with the circuit. This means much disconnecting, possibly having to cut and splice wires back together, etc. It can become a pain in the a$$ and take considerable time.

To alleviate these extra steps, use a clamp on amp meter (it is also multimeter if that is needed) ) that is capable of reading DC/AC current. These are fairly new, 10-20 years, and much easier to trace down dc current. They cost a little more than the ac only units but worth every cent extra. They are good for reading: alternator current, battery charge/discharge current; sporadic loads; tracing circuits; etc.

If the current being read is very low and you can break the circuit, make a coil of wire with 10 turns in it. Put this in series with the circuit wire and put the clamp through the center of the coil. Reading will be 10X the actual current. I have them with 10, 20, 50 and 100 turns. Wouldn't be without them.

Best thing about the ac/dc units is they can be used with any circuits. It also makes it easier to justify it's purchase to the wife, if she knows about those things.

Good Luck, Old Salt

I can't recommend breaking any circuits in a vehicle, the repair will never be as good as the original given all the environmental crud going on under the hood. Better to have the engine off, lift the negative lead, put your cheapie multitester set to the highest DC current range between the post and the lead, and pull/replace fuses one by one until your meter reads zero, then start tracing that circuit until you find the short or pin switch that's stuck closed.

Intention was to break circuits as an absolute last resort. Use of the DC scale clamp on a multi-meter is the primary method of diagnosis. It doesn't require anything other than clamping around the wire, turning the ignition or starting the car and looking at the meter. This is also a much easier method to trace the short/low resistance after the suspect circuit has been found. Example could be light circuit: is it the headlights; the rear lights; the parking lights; the lights on the side mirrors; or other lights on the same circuit. It also has a much wider range and accuracy than those amp meters that are held next to the wire when current tests are made. They have dual scales of 30 and 200 amps but I haven't seen them for sail in many years, at least 30 or more.

Also, with sta-kons and other compression butt spices it isn't hard to splice the suspect wire back together. This would be done after the clamp on revealed the suspect circuit.

I have done several problem cars this way and find it much easier and more accurate. This is especially true when fuse blocks are in difficult locations and contorted maneuvers are the only way to access it. Not all cars have it mounted where you can get to it without being double-jointed.

Good Luck, Old Salt

1. Check the fuse link at the Alternator.

2. Get a volt meter and check for the real voltage.

3. They offer a amp meter which tells the real capacity in amps your alt is putting back into the battery.

4. The best regulator is the one offered on the Chrysler product of the 70's. Your factory computer can be bypassed with this other type and it is about $25.

Tom Silver

If your vehicle still use an electro-mechanical type of regulator, a small rectangular box with coils and contact points inside, then it maybe the culprit.. At times those contact points sticks due to arcing that causes a short to ground /chassis connection and can drain your battery overnight... If this is the case, then you'll need a new one..

Good luck..

You did not state whether the vehicle is an early 1998 diesel model without electronic fuel injection or if it is a late year model wiht EFI.

It is very important that you know which model you have before attempting any risky electrical testing.

You also did not state if the alternator and/or battery you purchased is new or used which can also be critical.

All Diesel vehicles have very heavy duty alternators and the alternator in the 1998 dodge 2500 trucks is rated well above 100 amps so a small lighting or other small current short logically would not be the problem.

Start the vehicle and after it has operated for about 15-20 minutes, check the voltage across the (+) and (-) battery terminals with a digital voltmeter.

The voltage should be 14.5 - 14.8 VDC.

If the voltage is not within this range your alternator is not operating properly.

The next step is to determine if the alternator excitation terminal is receiving proper voltage from your ignition switch assembly.

In order to perform this test you must have a good repair manual and be competent in understanding the step-by-step procedure or get someone that is competent to help you do the testing.

In many cases the culprit in older vehicles when the charging circuit suddenly quits is failure of the auxilliary circuit contacts inside the ignition switch.

If the igntion switch is operating properly and you have the proper voltages to all of the alternator terminals, the "new" alternator is bad.

Batteries?? I'm thinking you have a 24V starting system that shifts to 12 V when running, correct?

There is a fair amount of electronical wizardry going on in there. How 'bout that word. I suggest you Google Dodge Ram forums, there are several. You have a 2nd generation truck. You can join all of them for free. Pick one you like, I'm certain someone else has had your problem. If not ask away.

I have used related forums with good results. There is even one for Cavaliers, and believe it or not, the high end Citation also has one.

Let us know

All comments noted with respect, when in this situation always start basic costless and simple ,,,check for a loose earth connection,engine to body contact is paramount

Farmer, jack of all trades,master of none

Had an older Mopar product that died same situation, spent +on new battery and a new alternator but died later that night , found a faulty headlight switch which was draining the battery. Disconnected the module and it charged and ran fine , just no headlights. Replaced module and no problems after that.

There is a very simple first check that some here have partially alluded to, but not exactly to my mind. Its simple to do as well...

It does not involve removing cables while the engine is running, which makes it safer for you and your vehicle electrics....

I find it VERY interesting and pointed that you state:-

"My batteries are draining while the engine is running...."

So they are not drained overnight or are you recharging the whole night? Please define what happens overnight....important!!

It could be a "device/circuit" only in use when driving.....e.g. when the ignition is turned on. Defective GPSs and telephone interfaces are known to have such problems. Usually, you can turn on ignition and monitor current "out" of the battery via the earth link with a clamp on ammeter (Beg, buy or borrow), then dropping out fuses one at a time till you find the problem....remember where each one goes.....

If that does not work:-

Find a voltmeter that measures up to say 20 VDC. Any, but an old analog might be best.

Connect it across the battery and note the voltage.

Start the engine and watch the voltmeter on tick over, does the voltage drop or rise or stay the same?

Increase tick over to about 2000RPM and note what the battery voltage does.

1) What should happen is that after starting, the battery voltage should drop slightly (as it is a reflection of the current that has just been drawn).

2) Then the alternator should replace the charge slowly at tick over, slowly increasing voltage. At worst,the battery voltage should not drop any further.

3) Then with 2000 RPM, charging should increase quite quickly, voltage increases to usually around 14.4 volts or maybe slightly higher on some makes....but it should stabilize at or before 14.7 volts. I personally prefer 14.4 VDC....but thats just me!!!

If the battery is defective, then it is possible that with a good alternator, it may "jump" fairly quickly to a higher voltage. Check battery water/acid levels are correct, but battery is probably damaged if levels are already low....

I feel it could still be a bad alternator. Was the replacement new or reconditioned?

Most of the problems I've repaired related to this issue are 'dirty' battery terminals...the corrosion that occurs can be a 'semiconductor' and allow power out of the battery, but not back in. If you haven't cleaned the terminals to bright lead, do so. After a client declined $20 to troubleshoot( 30 years ago) and replaced alternator, regulator, battery, and brought it back paid and I cleaned the terminal's (5min) he again had full function.

If you find yourself on the road when the battery terminal/cable clamp are corroded enough that there is too much resistance to turn the starter, take a screw drive and deeply run a straight mark from the post to the clamp on the top. Make sure you score it as much as possible. This results in a lead to lead contact between them. Also if you have a screw driver and something you can use as a light hammer, tap a slot on the top of the post/clamp. Doesn't have to be deep, just as much contact as possible with the slot.

Another method is if there is someone there who is capable of turning the key to start the engine try this one. Do the scratch thing and leave the screwdriver across the terminal and the clamp. Push down firmly or hard. This jumps the corrosion through the screw driver tip. The high current is why you want to have as much contact area as possible. If it doesn't work try some more ingenuity with the screwdriver.

If the lights go on but dim when the starter is tried, your problem is usually a corroded terminal/clamp. a low or dead battery or broken strands in the hot or ground cable from the battery. This reduces the effective size of the cable and the resistance reduces the available current and voltage to the starter.

Good Luck, Old Salt

You missed my point....sometimes the corroded lead between the post and clamp acts as a diode....vehicle may start, but the charging current is blocked and the battery is not charged. I've seen this happen on several occasions. Before I went back to school in '79, I owned and operated 2 Phillips stations...if you have this problem, clean the damned terminals, that thick layer of oxide and sulphates might be the problem.

geraldpaxton-

Yes, I know the sulfates are the problem and the clamp and the battery post or the side clamps and the battery connections need cleaned.

BUT, if you have this problem, clean the damned terminals, that thick layer of oxide and sulphates might be the problem (that's a quote) how the hel* am I going to do this at 11pm in a strange parking lot of a shopping center, on the shoulder of an interstate, being the last one to leave a PTO meeting, in a multi-level parking lot, at the beach, on some rural road, at my mechanically knowledge challenged relatives, at an overnight food stand, out camping, a 24 hour drug store at 3am, at the hospital emergency room, at the work parking lot when I am the last one to leave and a whole lot of other scenarios! GET MY DRIFT?

Do I reach into my pocket and pull out my wrench to open the clamps and my trusty battery cleaner brush? I know I should have cleaned the posts/clamps but maybe it isn't my car. I don't always carry a wrench and cleaning brush in my pocket, who does?

In a pinch what should I do? Walk the 10 miles home? If I have a small screw driver along I use it in the prescribed manner. If none I reach in my pocket and pull out a fairly new quarter, and use it to scribe several lines in the clamp/terminal. If I need a hammer I use my shoe, the bigger the better. Out of change, use a key on my key ring. I scratch several grooves as before and then use my shoe as a hammer as described above for the screwdriver. If possible I would use a key that is easily replaced, not the ignition key.

That's why I described this last resort method of getting the terminal/clamp in good enough shape to get me home. I've used it twice for myself (other's cars) and know several people who have used it. Learned it from a friend who is a tow truck driver. He cheated himself out of a tow!

Keep this in mind. I hope you never need it but in case you do you know how to improvise. That is one of the many special skills of engineering type people.

Good Luck, Old Salt

A nice "in a pinch" repair technique. However, most quick fixes don't actually fix the problem. They just allow one to forget about the problem until it happens again.

Actually I fix them, no need to diagnose the problem, my wife thinks she does that:

Car bounces on bumps and around corners; "check the oil"; bad shocks/struts

Car runs very bumpy; "check the ignition key wires"; flat tire

Air conditioning doesn't work; "check the air filter on the engine"; A/C not turned on

Rattle in front of car; "check the transmission fluid"; hood only closed on the first latch, needs to be pushed down some more to catch the 2nd latch

Etc., etc., etc.,

She learned it from her mother. She used to be an "Administrative Assistant" at a auto body/towing/mechanical repair shop. This qualifies her to know everything about anything.

A good atypical but plausible possibility that also fits the proffered symptoms. I like it.

They still need somebody that knows what they're doing standing next to this Dodge to find the problem.

"I replaced the alternator and batteries"

I join you in the alternator and batteries being the first things I would check. If nothing else they have the highest incidence of failure or on the way to failure.

My mentioning this rude and crude method was to assist anyone who gets caught without their handy tool box and meters. This is for when there is low current flow, lights work with only them or a few others too, but everything goes dead when the starter is engaged (the click, click syndrome).

Not strictly on the subject on the subject but good to know how to do it. Got tons of tools in the garage and basement shop but they don't do me any good if I don't have them. That's when improvising is needed. Thanks for getting me back on track for the next one.

Good Luck, Old Salt

I agree, this information is good to know, but, the OP's stated problem was related to not charging...the example I mentioned had replaced battery, alternator, regulator, et.cet. and still had the problem. The inside of the clamp had a heavy layer of reddish brown corrosion,(new battery, new post) and would start, the alternator developed voltage, but the system was not charging the battery. When this layer on the inside of the clamp was removed, everything worked.

Cumminsforum.com good knowledge base for this truck.....

Myself, I've got a 94 (mechanical P-Pump system). I had my alt go out with another 400 miles that I needed to drive. I just took some parachute cord and tied up the fuel shut off and drove the thing with the batteries disconnected. Reconnected when I needed headlights to finish the trip. Very temporary fix.

In order to troubleshoot this problem, do like the other poster's said and start disconnecting fuses until the problem goes away. That circuit would be where I'd start looking.

98.5 Dodge trucks (24 valve diesel) had issues with the intake heaters staying on. Check the relays mounted on the drivers side fenderwell.