Voltage gauge jumping around - Charging system

[JStangeland]

hi guys



been having some electrical gremlins playing in the charging system on my work truck.

last week i had to get pushed off the freeway (after blocking downtown san francisco traffic for half an hour) by the highway patrol when the truck completely died and had not even enough juice to run the hazard lights... anyway i bought a new battery to get home. after that i was putting the battery on charge overnight and running off of that until i had the time to look into what was going on with (what i thought was) the alternator.

i spnt a bunch of time in the archives but i couldn't seem to find what i was looking for.

in any case, since then the voltage gauge shows the alternator working intermittantly, sometimes charging, sometimes not.

any clues as to where to start looking?

as always, thanks!

jeff

 

[JGrefenstette]

jeff, from what youve said i would have to say it sounds like you ECM is crapping out on you. the same thing happened to my 93, but mine just died all together. i charged the battery and replaced the alt. it still wouldnt charge. talked with some guys on here and figured it was the ECM. got a factory reman for about $160 i think. from moparwholesale.com

good luck

 

[JFaughn]

Do tests to save money , unless your wanting to keep the economy going .
The ECM fail very rarely , connections are common , fuse's , fusible links , if you have a lot of mile on the alt then it could be the brush's , there soldered in so a hassle to change but is doable .
Here'e a link for parts .


LarryB's Dodge starting problems solved here.

 

[JStangeland]

hey guys

so here's an interesting update that gives another look at this whole electrical thing:
today the truck died on me at a stoplight; it started right back up again but five minutes down the road i made a stop and when i got back in the truck i turned the key and NOTHING happened. no dash lights, no nothing. the lights wouldn't come on either. i had plenty of charge in the battery, 12. 5V and i had been watching the gauge so i knew it wasn't battery related.
does this point at anything (like the ECM) considering what had been going on previously??
you guys are great! thanks for your insight!

 

[Philip]

There are two heavy wires coming off the postive battery post. About 8" from the battery is a splice in them. The next time it dies leave the key in and the door open. Wiggle the splices and see if the door buzzer comes back on. If it does the engine will start.



Then fix the bad splice.

 

[ekroman]

Check for a bad ground as well. Also check your battery cables themselves. Check insulation carefully, if there is a split it will corrode the cable from the inside and you may not notice.



Eddie

 

[PToombs]

Check the fusible links on the drivers fender also. It might also be the ignition switch, but I bet wires.

 

[JStangeland]

yep, you guys were right. it was the negative ground at the battery.
resolved that and got the truck running again at least, but the gauge is still jumping around.
i found directions on adding an external voltage regulator, bypassing the one in the ECM: FAQ
what do you guys think about trying this? or is the fact that it is charging at least part of the time indicate that the ECM's internal voltage regulator is functional and the problem is elsewhere?

 

[TBurow]

i did it when i put a first gen in my 96 gasser. it charges, but it also pulses at anything over idle. tried 2 alt's and 3 regulators. batts stay charged so i dont worry about it. all new wires so its not a loose/corroded wire.

 

[JFaughn]

From my experience & reading about these issues , I have seen very few failed ECMs , I think what some are doing is going around a problem they can not figure out by putting in the external reg.
More often than not this kind of work comes back to bite again because the root of the problem was never fixed .
If I got stuck in the middle of nowhere I would use a wire & sw to full field the alt for short periods till I get to where I needed .

 

[JStangeland]

Hey guys - back again!
Same issue, it resolved itself last time and the truck had been running just fine for the past year +, but has resurfaced.
So basically the issue is the voltage gauge shows the alternator sometimes charging sometimes not. I can see when it's charging when the needle sits where it usually is, but it sometimes drops off to show a lower voltage (which i am assuming is the measured stored voltage at the battery, vs. the voltage at the battery with the alternator charging. )
In the archives I have read that it may be the crank position sensor. Are there tests I can do with my multi-meter to determine if the somehow the output of the alternator is fluctating, or does it sound more like a wire connection, and any clues how I might hunt that down?
Thanks again!

 

[Greenleaf]

You need to read the outline of the charging system printed in the magazine. This will answere your question. Same problem you have described.



Issue 64

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