Is it the orginal alt? you may want to check amp out put of alt.

I am not a real big automotive guy, but I think most automotive charging systems supply about 13 to 14 volts to the battery when the engine is running (and turning the alternator). Try swapping out batteries and see if there is any change in voltage at the terminals. If the new battery shows a nice 13-14 volt reading, then good things are coming out of your charging system, and your old battery is the culprit. If the terminal voltage reads lower than the battery voltage before you run the engine, there are gremlins in the charging system. At this point I get ignorant and have to leave the problem to those who are wiser than me.

Have you surfed around to see what the codes mean?

All the best!

absolutely correct happy fish - the ouitput voltage should be in excess of 13 volts on charge

In order to know what the codes mean, I need the following info in addition to 98 Dodge diesel. Tell me if got these right or wrong.

I assumed:

pickup, automatic, non-California.

If these are correct, the codes had to do with the transmission, not the electrical system. Once you confirm or clarify vehicle parameters, will send specific code meanings.

And Happy Fish was correct on all accounts relative to the electrical problem.

You are correct. The truck is a 1998 pickup with an automatic and non-california. The batteries are so new that they only have about 30 minutes of running time on them. I took them to O'Reillys and had them fully charged while they checked the alternator. They said the alternator passed.......this one has me stumped.

ugh! alternator is dead.

Yep...

Check Truck's Body and Engine Earth wires. clean them.

Yeah !

If the ground path is not good, then nothing from the charging system reaches the battery.

Kudos, SKJ !

If alternator is truly ok, the problem is with the electrical control module. Dodges have a feature where some utilize the control module as a voltage regulator and when this craps out it is often misdiagnosed as a (bad alternator with internal regulator). The fact that the batt voltage isn't 13.? volts when running, and is lower when truck is running than when not running suggest this is your problem. Had the same problem once and a shade tree mechanic was the only one sharp enough to figure it out. Cost me a case of beer for the diagnosis and too much money for the replacement part.

If the O Rileys crew said it was OK. did they test it off the car, or on it?

Check for battery voltage at the alternator battery connection. Also check for good connections all the way back to the battery positive post. (there may be a heavy fuse near the battery itself) Also check the ground connections all the way back to the battery ground.

The fact that your voltage went lower when you started the truck indicates a non-charging alternator system. That can be more than just the alternator. Good luck.

It was off the truck. The O'Reilly's equipment was a "Dumb" test machine. It simply gave a pass/fail and didn't show how much voltage was being put out.

There had been massive, (quickly built up) corrosion on the battery terminals and cables. We neutralized these with lots of baking soda and water, but I'm not sure if that would attack any of the corrosion down inside the cables.

G'day,

You've received some good advice so far, the only think I'd add is the following.

The alternator should produce 13.8 to 14 volts when running at fast idle to about 1500 rpm. The voltage with the ignition and accessories off is about what I'd expect. If this situation is constant, i.e. has been like this for a while, I feel the alternator is charging okay. If the battery won't start the motor, and the voltage is still 11.9, look for a faulty battery or a short in your starter circuit. Definitely check the charge/discharge current between the +ve terminal to the electrical system, bypassing the starter current draw. On many vehicles you have a cable from the battery +ve to the starter and the rest of the system taken off that starter solenoid terminal. A -60-0-60 amp ammeter should be adequate. This will definitely show the output or drain of the alternator.

You can also buy a current shunt from someone like Jaycar, who have a US store. http://www.jaycar.com/ShowLargephoto.asp?id=6908&IMAGE=

Connect this from the starter to the system cables and then measure the voltage drop across the shunt.

Also check the voltage with all accessories off. Aircon will often draw about 6A just with the clutch and A/C fan running. Add another 6-8A if an electric condensor fan is connected. Naturally, turn the lights off for your initial tests.

If the alternator is okay, you should be able to maintain at least 13.0v with high beam on at 1500 to 2000 rpm. If the lights dim at idle and flare at revs, a crook battery is usually indicated.

If the alternator is putting out its rated amperage, look for a fault in the electrical system, maybe the tranny electronics.

If it ain't generating enough current at say 1500 to 2000 rpm, then replace the regulator. The brush holder often incorporates the regulator on Bosche units and are only about $AU30.00 in Aust.

I usually specialise in pre-crossflow Ford sixes an other carburettored motors.

I hope I've been of some assistance.

Let's know how you go

RRV

rrvau@inbox.com

I would take the alternator to an alternator rebuilder and get it checked. They are capable of doing a good diagnosis. It should have an internal regulator based on the year. It should be putting out around 14 to 14.4 volts. They can repair it for appx. 1/2 the cost of a rebuilt.

Hi, I'm not a Chrysler fan, haven't been in 20 some years, but 1st off I don't believe that there's any place where you can purchase parts to rebuild alternators, starters, or any of the parts we used to save about 1/2 the cost of new parts because when a service facility has to bill out at $60 to $70 per hour. Well, just go out & buy new or "remanufactured" --- throw away society. Getting back to your original problem, some manufactures use a logic in there vehicles' main computers (cpu) that "test" all electrical circuits before it allows the alternator to start returning a charge to the system. An alternator (or generator) is a pretty simple device that has to have a controlled magnetic field to control its' output. Check to see what voltage is being sent to the "field" terminal. Personal experience from 3 Fords , an older Toyota, & VW. Don't discount those fault codes conserning the transmission -- I had a '97 F350 that threw codes indicating tranny problems that was actually a cam sensor. Also check ALL your trucks' electrical plugs/connectors, could be corroded one. Cars have gotten' to the point that one has to have a PHD. in auto technology in order to understand their faults. Good luck. George in the Berkshires.

GA from me.

I would have written the same if you hadn't beaten me to it!!

Check this site out: http://www.fixinrams.com/

It's saved me a pile of money with my trucks.

If your alternator checked OK off the truck, the problem is the truck itself. The site here should be able to get you a simple wiring diagram of the charging circuit of your truck. If you have checked the positive post of the alternator, against the alternator housing with your voltmeter, and the reading is the same as the battery voltage, the only thing that should keep your truck from charging is the ignition switched control circuit. That is where the wiring diagram is needed. Good luck.

If you can not find a diagram by Monday, I should have access to one then.

hi it's sounds as if electric going to earth virer the key

Alex kypriadis

We put one probe on the positive input terminal to the ECM block and one on a ground and got continuity. All battery cables are off the batteries and all battery cables are off this module. The alternator is off the truck and we moved the ignition switch several times with no change in the continuity. We pulled the 50amp battery fuse in the upper left corner of this module and the continuity stopped. What could be causing this and are we assuming correctly that there shouldn't be continuity?

Continue further. With the 50A fuse back in, remove the other fuses one at a time, and watch for the continuity tester to show continuity is gone. Once that fuse has been determined, check the items on that circuit.

Two things to consider. 1) is there a cigarette lighter stuck in as if it were heating ?

2) There could be two or more circuits that are giving the

results you just stated. If no one fuse will stop the

continuity, go back and pull one end of the fuse out and

leave it out and go to the next one. This will allow you to

have all of the fuses out without loosing what space

they belong in. Good luck.

I forgot to mention that we removed all of the other fuses one at a time with the 50amp fuse in place. We had continuity at all times until we pulled the 50amp battery fuse. The cigarette lighter is missing, so that plug is empty.

We pulled out the ignition switch and it tested fine. However, it is possible to move the ignition switch over to the accessory position with the key out.

We'll try pulling multiple fuses at a time out and maybe hit pay dirt.

We appreciate all of the help!

Do you have access to a wiring diagram of the truck? If not, maybe someone could help him out?

We have a wiring diagram and found that the continuity went away when we pulled the IOD fuse (Ignition Off Draw fuse). We are pulling 3.5 ohms when the fuse is installed (using chassis ground and positive input on the power distribution center). We can't find anything that is left on. Any ideas?

The Glove Box Light, Interior lights Interior light timer, Memory and Clock in the Radio. Engine Management Computer Memory. This is a start. Follow what is powered by the IOD fuse. One at a time, disconnect each item and check the reading.

Radio, some have 2 power connections, one permanent to keep the tuned station memory active, the other for when you actually listen....

Just a thought.

I had an charging problem some time back. The way I found out was to take the negative post lose from the battary for 3 or 4 seconds and if the motor dies, the alternator is not charging. If it is operating correctly it should stay running.

If it dies then I would have it checked out at an alternator shop. Then you will know if is truelly the alternator or something else. And since you already have new batteries that would rule out the batteries.

If you take a volt meter and read across the posts on the battary it should read from 12.5 to 15 volts if charging normally.

Hi,not sure if this is fixed yet ,I have 1998 also and when they replaced the batteries they shorted out one of the positive cables that blew a fuse for the alternater. the fuse box next to the battery has a 140 amp alternator fuse. it is easy to find as all of them are labled on the cover of the fuse box. I installed a new fuse and got 14 volts again. good luck.