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90 W350 Cab and Chassis
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Discussion Starter · #1 ·
I was trying to test a parasitic draw and am unable to get a reading. With the negative disconnected I noticed the door buzzer and dome lights turned on when I open the door. Then I tried to start and it fired up! I knew this truck had electrical problems, but this is a new one to me.

Ok so how the heck do I troubleshoot this? I would think that the ignition wouldn't work at all if the + and - are tied together somewhere. That should create a short right? And where the heck is this rogue ground? Shouldn't the tires isolate the vehicle from getting an earth ground, and the electrical system only get a ground through the battery? I am thoroughly perplexed.
 

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Not an electrical expert, but I'll throw out some ideas.

Forget about earth ground and tires and such. Your vehicle doesn't ground to earth, it grounds to the battery.

I could be wrong, but I'm pretty sure the starter is grounded through the engine only. So something in that circuit might be making contact with the body or frame. Possibly the engine and or the starter itself is making contact somewhere other than the ground strap. I've never seen an internal short in a starter but I suppose it could happen.

Still doesn't explain how it's getting back to the battery. You could have multiple shorts. I'd probably disconnect the battery until you have this figured out or are ready to troubleshoot. I'd hate to see your truck burn to the ground.

Smarter more experienced guys will probably be along soon to educate both of us :)
 

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1989 Dodge Ramcharger 4x4
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Only one side + of the battery is connected to the truck, and it’s still powering up. That’s some bad juju- voodoo shit right there. Better drink some holy water and piss on it. Then burn it to the ground and crush it. Before it starts chasing you around town trying to run you over.
 

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I'd be looking for another battery. It is not possible for one to start without completing the circuit.
 

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90 W350 Cab and Chassis
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Discussion Starter · #6 ·
I tried to get a video of it starting this morning and got nothing. No lights, no buzzer, nothing. Checked voltage 10.2. Tried to charge it and it wouldn't take a charge. Took it back to advance auto and they said the battery is bad, also it's 4 months out of warranty... Ok paid for a new battery and by the time I got home it started down pouring.

More to come.
 

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Dumb question.....but is it by chance a dual terminal type battery (top and side terminals) and you forgot to remove a ground from the side terminal?

good point KT , thats why they give you the BIG money
 

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Yes it all grounds through the battery. But the entire frame, block & metal body panels should be a part of this ground.

That's why most boats require so much wiring, the vessel itself is non-conductive, everything electrical has to have a separate ground wire.

Bucky
 

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You mentioned doing a parasitic draw test, you didnt have the meter connected when the ground was off did you? If so the meter would create a path to ground.
 

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You mentioned doing a parasitic draw test, you didnt have the meter connected when the ground was off did you? If so the meter would create a path to ground.

that would either blow the 10 amp fuse in the meter or melt it down
 

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that would either blow the 10 amp fuse in the meter or melt it down
Yes it would, but for a split second he may have had life. Or he could be doing a draw test from some billy bob video he watched on YouTube and it could be totally wrong.
 

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Discussion Starter · #14 ·
Ok so after replacing the battery I am getting results with the amp check. I'm measuring .250 amps from the lead, and if I touch the probe to the frame I get the same reading so something electrical is making a connection with the frame.

I have no idea why the truck started with the negative terminal removed from the battery before, that blew my mind. More troubleshooting as time permits.
 

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that is a normal draw / with positive terminal hooked up and checking from the negative terminal to body/frame that slight draw is PCM/radio memory

you should have NO draw over half an amp 0.5
 
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Discussion Starter · #16 ·
Ok so here's an update. Today I dropped the gas tank to troubleshoot an intermittent electrical connectivity issue with the fuel pump (Also the fuel gauge was in open circuit status) . The connector that connects to the top of the sending unit wasn't giving me good connection and if I wiggled the wires it would establish a good connection and the fuel pump would work. I bypassed that connector by running female barrel connectors to the top of the sending unit and coated everything with dielectric grease then filled the cavity with black RTV. I then ran the leads to a weather pack and connected that to the main harness. I tested connectivity before installing the ending unit back into the gas tank and had great connectivity from the weather pack to each of the terminals inside the sending unit. Intermittent problem should be solved. I "bench" tested the sending unit by turning the key to run (not start) to see if the fuel gauge would read. It moved far to the right toward full instead of moving toward empty. I moved the fuel float arm but the gauge didn't move. Okay, I can live with an inoperable fuel gauge for a while as long as it starts every time.

I wrestled the tank back up into place and was excited to turn the key. Watched the fuel gauge move to full even though I know it's almost empty. Turn the key to run and.... nothing! Not even trying to crank the engine. WTF. I hate electrical problems...

I took a peek at the starter and the ground wire has lost all of it's shielding and isn't getting great connectivity when I tested it to the battery ground. The ring terminal and screw are good, but the wires coming out of the starter body are weak and not consistent. Maybe I need a new starter? I'm so tired of electrical problems... Mechanically the truck is great, electrically it's an inconstant pile of shit.

Any ideas to start troubleshooting?

I checked codes and got nothing of interest (12,33,55). I checked voltage (12.8) and when I turned the key to start it never dropped, so i'm guessing that it's not trying to engage the starter. Something is going on between the key and the starter, what and where I have no clue.
 

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Starter relay, neutral safety switch/clutch safety switch would be the place to start looking. The relay is on the fender with the other relays, don't remember which one it is.

Motor vehicle Automotive lighting Bumper Fixture Automotive exterior
 

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I wrestled the tank back up into place and was excited to turn the key. Watched the fuel gauge move to full even though I know it's almost empty. Turn the key to run and.... nothing! Not even trying to crank the engine. WTF. I hate electrical problems...
I recently had a problem with mine not starting. Turn the key... nothing. Occasionally it would start, but then nothing again. I wiggled the wires on the ballast and it started. So I cleaned up the terminals on the ballast and it has been starting good every time.
Except now the starter sounds like it's crunching gravel, so now I have a new problem. LOL
 
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