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Discussion Starter #1 (Edited)
Here's the issue - driving the truck to work this morning I got a low voltage and a 'check gauges' light. The truck was running fine...so I figured I'd mess with it after lunch.

Went out at lunch and she started right up and ran great, but I still had a low voltage reading...

Drove her home from work, and right when I exited the highway all of the power accessories died on it, radio, lights, etc. The airbag and all warning lights came on briefly, then everything died (including blinkers, etc) but the truck ran fine. Made it to my driveway, pulled in and shut her down.

Now she wont click, crank, nothing - alternator or battery?

Any input is appreciated.
Thanks,
Shawn
 

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It sounds like the alternator to me. The alternator isn't charging the battery enough to run all of the accessories. And when you go to the parts store they can check the battery and alternator while still on the truck.
 

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Discussion Starter #3
Well, Changed the battery first because it was dead, old, and the winter took a toll on it...not to mention the corroded posts.

That didn't fix it. It started with the new battery, but when I turned on the lights, HVAC Blower, and used the power windows - I could see the voltage drop on the gauge.

So I then pulled the alternator off and took it to have it checked. The first time we tested it, it failed. The 2nd-6th time, it passed. Strange...but I got a new one anyway as the old one had a loud bearing.

Installed it, and she's good to go now!

SQ
 

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When testing the alternators most machines won't put it under a load to determine the actual voltage from the regulator and how many amps its ultimately putting out. Thats probably why it tested good, it was just checking the internals.
 

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Every Time
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I agree with tiny, an alternator should be checked on the truck both at idel and load conditions
 

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Big Green
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Yep but glad it works now sounded like the Alt to me.
 

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Guys I got the same issue as ShawnQ originally described (happened the same way) but I have swapped out the battery (cause it was old) AND alternator (cause it was old) and still NO LUCK. I can charge the battery up (since I have drained it dead now in 1 week) and within 50 miles of driving it is completely dead.

I installed a new alternator, took it back out, had it checked and it tested just fine. They then tested my old one (cause I didn't bother the first time) and it worked tested just fine too.

No idea where to look now. Any ideas?
 

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is the battery draining while your driving, or just getting discharged while its setting?
 

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Cyron, we put a multi meter on it while running and were not getting any charge (it was like 10 or 11 if I remember correctly). It is like the truck is telling the alternator not to charge. When we put in the new alternator we got the same numbers off the multi meter, basically no charge taking place.

tiny_9755, the battery is draining only while running. While driving it drained a brand new battery in about 30 miles with the lights on (drained it to dead). We recharged the battery overnight and then did all the alternator gymnastics (testing the old, putting in a new, testing new, etc) and it drained the battery to dead again at idle in about an hour. The needle on the battery gauge started at about 12 and worked its way below 8 and then blinking lights on dash and dead.

Very frustrating. Is there some kind of regulator that tells the alternator not to charge or something like that. We checked all the fuses and they look good.
 

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Big Green
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I believe the regulator on our Rams in internal you replaced with a new one? It should be under warranty so trade it out. I just installed a starter and found it was bad as soon and it was brand new it happens.
 

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do you have a parts store near by that can load test the alternator?
 

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Bridal Veil Falls
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You should check the alt while it is running disconnect the battery and check the alt with a meter....

If the truck dies when you disconnect the battery it is the alt....
 

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I have a similar issue. Have a 2002 Dodge Ram 1500 with a 5.9. Have had it for a couple of months without issue. Alternator was working fine but had a loud whine to it because of the bearings. Previous owner said it was like that for years. I didn't like the noise so I replaced the alternator with one from Autozone. After driving it for 5 to 10 minutes the voltage gauge drops to the far left and the check gauges light comes on. Autozone tested the Alternator and said it's only putting out 12v. I got another one from them and had the same problem. I put the old one back in and had the same problem. Must be something new that happened when switching the alternator out. Any ideas? Battery test is good.
 

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iirc the dodge ram VANS have an external voltage regulator. I know someone with one and he went though hell and back getting a new batt and alternator only to find out he had an external voltage regulator. BUY A GOOD ONE! lol he got a cheap one from lordco and it lasted 2 weeks and then packed it in, they gave him a different brand and hes been good ever since
 

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I was afraid it may have something to do with the computer. I bet that won't be cheap as its probably several hundred dollars for the unit and then you need the dealer to flash it to make it work for several hundred more. Not sure it is worth it for my truck with almost 200k on it.

Am i in the right ballpark, is that what you are saying?
 

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Voltage regulation is controlled in the ECM unfortunately, so when that goes out a swap is in order.
External bypass is possible, I have done it and had a DIY on another forum, but I took it down and I couldn't tell you exactly how to do it. Its simple, but you gotta know what wires to hook up to where.

You can get a re-manufactured one flashed with your VIN info for $150 from ebay.

BTW, I have heard more than once not to disconnect BATT while running, you risk trashing other components when doing that.
Should read around 14V while running, if less you have a problem.
Check wiring, check fuses - If the ALT tests good then its the voltage regulator.

Murrays [O'Relieys] Has a top of the line ALT load tester.
 

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Same problem here.

The Pickup is running in a a emerengcy setting wont shift in O/D and running rough.

I have checked the alternator it was only charching 12.2 V with 2000 RPM.

I got the alternator out and let it chechked and it was ok???

Wich fuse can be bad?
Can you give us the link for the DIY for the wiring?

Wher is the voltage regulator placed?

I don't know what to check else.


Thanks and greetings,

Erik.
 

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The ALT fuse is the first fuse in the fuse box located in the engine compartment.
Services manuals say there are fusible links in the ALT circuit too, I was never able to find them.

The concept of a regulator bypass is simple.
Take a cheap $10 voltage regulator and splice it in the system to take over that function from the computer.
Only down side is that the computer will of course still detect a problem, and the GEN light will remain lit.
I did it in my truck and ran it like that for a few months with no problems, I then had another problem related to the PCM and ended up getting a new one, so I didn't need the external any more.
This was a while back and, while its a simple 2 wire connection, I don't remember exactly how I hooked it up, so am not going to offer technical advice I am not sure about.

This may or may not help
http://thedieselgarage.com/forums/showthread.php?t=58251
Keep in mind, once you get the regulator, you usually have to buy the connector as well, doesn't come with it.
Some times its in stock, some times they have to order it.
 

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Mhh that can be the solution for the voltage regulator but it won fix the transmission...

On lead from the regulator goes back to the transmission control relay look at the picture.

Another strange thing is that I dont get a alternator light only a signal chechk gages...

 
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