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2nd Gen Ram Tech1994-2001 Rams: This section is for TECHNICAL discussions only, that involve the 1994 through 2001 Rams. For any non-tech discussions, please direct your attention to the "General discussion/NON-tech" sub sections.
Please remove your headlight switch and double-check the switch's connector harness closely. Many times when the switch overheats, it will loosen or melt the terminal connectors that plug into the switch. Aftermarket headlight switches typically supply a new headlight harness with the switch for this very reason. Also, please check the wiring coming into the headlight switch's connector block to ensure they aren't causing your short..
Thanks for the reply. I will do that tomorrow.. I have three extra switches that I pulled from boneyard Rams, they all tested good before this became an issue. I have swapped all of these in/out to see if present light switch might be the problem....nope....fuse still blew....immediately. But I will check the inside of the wiring harness connections at the switch for compromised contacts and or melted wires. Thank you.
So...if thats true...looks like I'll be cutting into wiring harness in search of this pos short. Damn it. I love this truck but the recent headaches.....could just put it out to pasture
Never heard of this method. But that would be very vague method anyway, as the ohm reading depends on how severe the short is. Now OP has the issue where 15 amp fuse goes instantly(?), meaning ohm reading would be somewhere around 0,0-1,0 ohms.
Best way to find the issue is to isolate circuits. Instead of blowing fuses, multimeter is useful. Set multimeter to beep, place one lead to negative battery terminal, and the other lead in place of the fuse. Not the battery side, but circuit side. Then set the multimeter to beep, and start pulling the wiring. When the beep stops, you are close. Also pulling the bulbs might help. It's rare, but filament in bulb can melt so it doesn't glow, it just burns the fuse. I've found this issue twice, and latest was a weirdest thing ever! It was shuttle type bulb, and that circuit kept blowing fuses. I went though the wiring, didn't find anything. I had taken the bulbs out to chech the holders, they were good. But didn't blow the fuse when the bulbs were out. Installed bulbs as the filaments were not broken, but fuse went once again. Then I looked the bulbs more closely, and noticed that filament on the other bulb looked like more "solid'. Got new bulbs and all good, lights work.
So what exact setting do I position the multimeter to....20ohms, 200ohms? I've got a SouthWire meter, not really an expert in its use.
2002 was the weird year where the 1500 was already the 3rd gen while the HD trucks continued with the 2nd gen model so service information is hard to come by. Does your PDC look like below, and is the fuse labeled "PARK LPS" the one that blows ? It should be a 20A according to the FSM.
Set the Ohmmeter to the smallest range, disconnect the headlamp switch and check the individual wires to ground.
...I believe the diagram is the layout for my 20 2500 gas. The 'parking lamp',(PARK LPS) fuse in my power distribution center is located at #19, as indicated from underside of PDC cover.....or position 'F' in above pictured diagram, but calls for a 15amp fuse. When headlamp lamp switch is positioned to parking light position (running lights as well) that fuse POPS immediately....no hesitation....POP!! So this has got to be a pretty bad short.....SOMEWHERE!!
Now the small fuse panel located at the interior of cab, lower left side of dash facing the drivers door, that fuse panel also has a 'PARK LPS' fuse but it is not a 'mini fuse', larger looking fuse that is a 20amp fuse. I've checked that, and it too is good..
Ok that checks out. In the wiring diagram the fuse is listed as 20A which is why I wanted to make sure we're talking about the same fuse. According to the wiring diagram the headlight switch connects this power feed to pin 1 (black/yellow) and pin 14 (tan) in the larger connector. Start there, disconnect the headlight switch and measure resistance to ground at the plug.
Edit: It would be more useful to use a test light instead of an ohmmeter. Light bulbs are low resistance connections to ground so the readings could be inconclusive. Connect the clamp of the test light to battery positive so touching the tip to anything grounded lights up the test light. If the light is bright it's a direct short to ground, if the light is dim (and the associated light bulbs are lighting up dim as well) the circuit is good.
06-18-2023, 10:43 PM
