2000 Ram 1500 5.9L. I've isolated a short down to the radio power wire (continuity with ground at the head-end connector). I'm trying to find Joint Connector No. 5 so I can start tracing the wire, but I can't locate it. I've seen Fig 24 on page 8W-90-28 of the 2001 FSM but it's not helping me. It looks like it should be just higher and slightly to the driver side of the brake lamp switch, but there's nothing there. Not sure if that's a difference between 2000 and 2001. Any tips? I tried following the loom, but it almost immediately goes into a plastic/vinyl conduit that goes down to the driver footwell and left over the cluster.

Thanks,
Matt

 

Behind guage cluster in a hard plastic protectant sleeve that is held on by a screw it's a b**ch to get to

 

From the top? Do I need to drop the dash to access it? There's a plastic air duct in the way which looks like I might be able to remove if I can get to a tiny screw in the way... Was hoping I could get to it by pulling the cluster, but as you probably know that was a no-go.

Just to make sure I'm on the right track, I'm seeing a massive parasitic drop (basically a short, but I guess not enough to blow the IOD fuse) which goes away when I pull the IOD fuse (even when the radio is disconnected). I assume PWR on radio is the low current always on power to keep settings and show clock (?) and ASC is the real power source for the radio which is routed via the fuse in the junction block. The radio stopped working a few years ago, so I suspected it and started there, but just want to make sure I'm understanding things correctly and am not chasing a red herring. I can't think of a reason PWR on the head unit connector would be continuous with body ground, but I might be missing something.

 

I messed up won't year truck. What exactly is it doing? Be as detailed as possible.

 

Went out this morning and tried a few things. Symptoms have changed a bit-- not sure if it's because I changed something when I dropped the dash last night to poke around a bit or if I was just rushing yesterday and was wrong about what I had seen. Battery was on battery tender all night, so it's at 100%. I previously had it tested at two different places and it read good. IOD fuse was pulled yesterday and I started debug today with it still pulled.

1. Pulled negative lead and inserted ammeter in series with neg leads and neg pole of battery. Showing around 20 mA draw.
2. Reinserted IOD fuse, draw did not change and interior lights still did not come on.
3. Turned key one click, no change. Pinger still on, no interior lights.
4. Turned key to second click, draw increased to 65 mA and pinger stopped. Cluster didn't move. Voltage drop is massive, over 10.5V.

I'm starting to think battery now, even though it tested good, since it's showing correct unloaded voltage but drops to near zero with a modest load. But it's weird that I saw a short to ground on the radio power connection. I can pull the battery from our other car to test. It's a lot smaller so it might not have enough power to crank, but it should have no problem with accessories.

Quick edit: I just hooked up the jumpers to our other car with my battery disconnected and everything seems normal electrically. I'm going to swap the battery even though this one tests good and see what happens to make sure I have a known good battery to continue diagnosing. My suspicion at this point is that I had two problems: a bad battery that tested good plus a pinch in the radio connection somewhere that I "fixed" when I dropped the dash. If that's what's going on, I still need to track down the short, so still need help finding Joint Connector 5.

 

2 things that come to mid reading this... battery could have an internal short explaining the severe voltage drop when load is applied. second. it could be a resistive load / bad battery connection. was the voltage drop under load witnessed by gauge or volt meter on battery? if volt meter on battery you are on the right path with the known good battery test. if it was by the gauge, then it could be a loose battery connection or bad battery cable.

i've rarely come across any harness issues unless it was a factory defect that would affect many of the same vehicle, the vehicle shakes violently due to daily use rough roads or extreme duty usage like a semi tractor, or the vehicle was in an accident or had a major repair like engine/transmission replacement, or extreme old age. basically if the harness is subject to severe and unusual conditions for most vehicles. 99% of the time, it's a bad battery, bad battery connection or a fuse/component failure.

 

I swapped the battery on Friday and so far everything is back to normal. Looks like the battery was the root cause, but there were some weird diagnostic results that confused things. To answer your question, the voltage test was between the battery neg pole and the positive lugs on the PDC. Interestingly, voltage was fine when I measured + to - on battery. I only saw the drop when I went from - on the battery to the PDC (I also swapped that cable, thinking it was bad, but it was fine).

First, the battery. Tests at two different places were good. Since I still suspected the battery, l pulled it out of the truck, charged it up to full (using a battery tender, so it was really topped up), removed the charger, and left it overnight. Voltage was perfect the next day. I don't know how the battery is arranged internally (it was a Duralast Gold), but I wonder if it has multiple 12V cells in parallel to provide the listed CCA and some of those cells failed. So, while it read good voltage it couldn't meet much draw. It's a bit over five years old, so it's not necessarily a surprise that it went bad, though.

Second, my radio has been dead for years (I've gotten so used to the silence I turn off my wife's radio when I drive her car alone), so I suspected that and it seemed to be confirmed when my ohmmeter showed continuity with ground on the radio power wire. I haven't gotten around to repeating that test, but I did drop the dash when I was looking for joint connector no. 5, and I wonder if I un-pinched a loom somewhere. If there was a partial short over years, that could have led to the battery issues too. I've dropped the dash quite a few times for various things (heater core and evap being the two most recent), so I def could have pinched something at some point. Plus, the dash is apparently made from the most delicate crystal now, since if I look at it the wrong way pieces crack off. At some point I should probably track down this potential short, but I'm afraid of breaking off something really important, and for now the truck is working and I'm happy.

Thanks for being a sounding board. Sometimes when you lay it all out in writing it slows you down enough to realize you've overlooked something.

Matt

 

i've been researching the brittle plastic. almost all of the interior plastic is abs... here's some videos i've found that might be helpful.