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Discussion Starter · #1 ·
Hello all,

I've been mulling this over for a little while in my spare time and I thought I'd throw it out here now to see if any of you have any experience that can help me fix this. A couple weeks ago I was on a trail ride up in the mountains nearby, and while at a stop, I noticed that my new Optima battery was leaking acid out of the weep holes on the top of the battery and the battery was starting to bulge at the top. :eek:
After I got down the mountain, I checked it out, and it turns out that my alternator is charging my battery some times at 14.3 -14.5 volts but most of the time from 14.9 to 15.3. Trouble shooting guide says it shouldn't get above 14.8 volts max So I swapped in an old voltage regulator that I know was still good, and the problem persists. With the key on but the truck not running, I check the battery voltage: 12.5 volts. Then I checked the voltage leading to the voltage regulator: 11 volts. Huh? Looks like there's a voltage drop giving a faulty reading at the regulator causing the regulator to keep charging. So I do a little investigating with the wiring diagram and volt meter. firewall conector: 0.1 volt drop, Ammeter: 0.1 volt drop. ignition switch: .35 volt drop. These are the only places in the circuit I could think of that would have the potential to develope resistance to cause a voltage drop like that. Currently my suspicions point at the ignition switch since this is a point of wear, but it still doesn't account for the full voltage loss. Can anyone out there tell me if I'm looking in the right direction here, or am I forgetting/missing something?
Thanks in advance.
 

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I would say you are heading the correct direction. Only other thing to do is to trace the two field wires and look for any obvious problems such as cracked insulaton, corrosion, bad splices, etc.

Since the VR is over-compensating for high resistance somewhere in the circuit, the green field wire (running bewteen VR and alt only) should be fine. The problem has to be somewhere in the ignition-switched power field wire circuit.

Even though the voltage drops you found are minimal, I would clean & re-tighten those connections anyway. Though .35 volt drop through the ignition switch does not seem bad, that is most likely where the problem is. :-\

-SM
 

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Discussion Starter · #3 ·
Thank you, it's good to hear some feedback on this. {cool}

On a related but separate note, This truck has always been a bit tough to start. So I checked the voltage between the positive terminal of the coil and ground with the key on but not running and I measured 5 volts. That seemed a little bit low to me. I checked the resistance at the ballast resistor, both in spec with 1.2 ohms on the primary side and 5.2 ohms on the auxillary side. I checked the Haynes manual and they say that if the voltage is not within 1 volt of battery voltage, and the ballasat resistor is good, then either there is a short or high resistance in the wiring going to the coil, or the starter relay is bad. I don't see how the starter relay would have any effect on this since the current to the coil doesn't pass through the starter relay. Maybe they meant the dual pickup start/run relay for the dual pickup style distributor equiped trucks?
 

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5 volts at the coil is way low, it should be closer to 8 volts with the key in 'run'.

Your ignition-switched power wire is definitely losing power to high resistance somewhere along the line. Did you check the ignition switch harness connector? The pins in there can corrode too, even though they are in the cab.

I would work back on the ignition switched power wire from the VR until I found where that 1.5 volt drop in the circuit is going to...

Have you spliced into this wire for anything like an electric choke?

-SM
 

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Discussion Starter · #5 ·
Slanted_Mind said:
5 volts at the coil is way low, it should be closer to 8 volts with the key in 'run'.

Your ignition-switched power wire is definitely losing power to high resistance somewhere along the line. Did you check the ignition switch harness connector? The pins in there can corrode too, even though they are in the cab.

I would work back on the ignition switched power wire from the VR until I found where that 1.5 volt drop in the circuit is going to...

Have you spliced into this wire for anything like an electric choke?

-SM
I agree that seems way low. Now bear in mind that this is with the key switch on but the engine not running. Perhaps the ECU has it switched partially off? Just a thought. ::) When the engine is running, I see a "flickering" 8 or 8.5 volts. Bear in mind that this reading is a "pulsing" voltage due to the on/off action of the ECU while the engine is running. I don't know maybe there's nothing wrong with the ignition at all and the hard start is due to carb maladjustment. Maybe I shouldn't go looking for trouble. I should concentrate on fixing the overcharging first, but then again, maybe they are related. Your thought? ???

P.S. BTW, no I haven't hacked into any of the wiring, it's pretty much for the most part pristine. However while I was troubleshooting, I noticed that the power connector from the ignition switch was warm whereas the turnsignal connector was cool. So I checked the voltage drop across the connector with the key on and I got zero voltage drop. That confused me. Maybe I ought to do it again with the engine running. I know that you're not going to see any voltage drop on an "open" circuit. Current has to be flowing in a complete circuit for deltaV = I*R (kirkov's law) to apply.
 

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If you have ~8 volts at the coil when running that part of the wiring should be OK.

Sounds like you have an excessive draw from the ignition-switched power field wire somwhere along the line that the VR is trying to compensate for. (which is why I asked about the electric choke above)

As to the hard starting, I would check the magnetic pickup air-gap in the dist. .008" with a non-magnetic feeler gauge.

Ignition switch is looking more and more like the problem...but I am unsure??? I wouldn't replace it until I exhausted all the cheap (read: free) options/tests.

-SM
 

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Discussion Starter · #7 ·
Here's another wierd electrical problem I figured out last night:

When I turn the key switch on, my turn signal and horn won't work until I shift into reverse. After putting it in reverse, they will both work in any gear I put the shifter in, until I turn the key off. Then I have to shift back into reverse to get them working again. The neutral start and reverse lights switch are on the same switch in the transmission.
 

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Anytime there are weird things happening in the electrical system, check all the grounds. The battery should ground to the engine, from the engine one should run up to the firewall. There may also be a ground that runs from the neg. battery clamp to the radiator core support. There are some grounds that are at the right side & behind the instrument cluster, also around the bracket that holds the key buzzer and the intermitent wiper control box near the steering colum.
 

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sound like my elec night mare too.. mine was a faulty iggy switch.. and the plug in the coloum was coroded....not all but only a few wires....
 

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sorry to hijack it but i am going throughthe same thing with my 71 dart....
makes me think about whats going on with the beasty (71 dart).... maybe i should change the iggy switch just so i know thats not the intermitent problem its having.... one minute its running fine the next it stalls and wont restart... sounds familiar huh???? maybe i should do both the truck and the dart because i was only getting like 4 volts at the coil when i tested everything after the shop could not find anything wrong with it..... i will definatley keep my eye in this post!
 

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i have fought some odd ball hard start problems with the
75 r/c .......untill the other day i removed the jumper harness
from the neutral saftey switch and found some wires just ever
so slightly rubbed through repaired that and so far no more
starting problems
 

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Discussion Starter · #12 ·
I bought a new ignition switch recently and as soon as I get that installed I'll let you all know of the results. I'm considering a new neutral start switch as well since the turn signal problems seem to be related. Will let you all know if that helps.

edit: here's a picture of the current state of disassembly of the steering column

 

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Is that just the way the pic is, or are they different?
 

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Discussion Starter · #16 ·
Yes, there is some difference between the two. The wires are different colors and longer, and the two power wires have diferent connectors on them. The original used spade connectors there, the new uses a female "bullet" type connector. I'm going to have to modify that. O yeah, maybe this is what you were asking, in the first picture the main connector is turned on it's side, so it looks different.
 

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Discussion Starter · #17 ·
Hello all,

Just an update on this, I replaced the ignition switch the other day, and the charging system seems to be running normal now. Charging around 13.95 volts now instead of 15.3 volts as before. I will keep an eye on it for the next couple of days, but right now, it's looking like the problem is solved.
 

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McGuyver said:
Hello all,

Just an update on this, I replaced the ignition switch the other day, and the charging system seems to be running normal now. Charging around 13.95 volts now instead of 15.3 volts as before. I will keep an eye on it for the next couple of days, but right now, it's looking like the problem is solved.
Thanks for the update Guy. Mine has been charging a little on the high side too, but not as high as yours. It hasn't caused any problems yet though.
Now I know where I can start looking!{cool}
 

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Discussion Starter · #19 ·
Just as a side note to this, I discovered that the MSD blaster coil I had on the truck was causing the wires running into the ignition switch to run "hot" due to the MSD coil's lower primary winding resistance = higher amps. I put the OEM coil back on, and the wires are running cooler now. I suspect this may have contributed to my ignition switch going bad.

I still suspect that I may have a ground problem in my wiring though. The turn signals, horn and reverse lights are acting flakey, (some times they work, sometimes they don't) however I'm thinking this is probably an unrelated problem(?) ???

P.S. Kendall, you may want to make sure your alternator mounting brackets are tight and have a good ground. Early on when I was troubleshooting this problem I discovered the alternator mount bolt was loose. This may have been the source for some of the initial extremely high charging I was seeing.
 

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Just an FYI (For "Y'all's" Information)... ;D
Like I mentioned earlier, my voltage has been a little higher than I thought it should be. After reading this post, I cleaned the contacts at the half moon shaped connector from the ignition switch, and also cleaned the bulkhead connector contacts.
My voltage is now at a more respectable range.... 8)
 
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