Ram electrical problems

Symptoms of the Ram’s electrical problems include:

The gauge cluster going crazy. Sometimes some of these symptoms occur; other times most; sometimes even all of them occur at once.

  • Check Engine light illuminates, sometimes briefly, sometimes for 10-15 seconds, then turns back off
  • Various gauges go dead and either immediately come back or stay dead for a random period of time. The fuel gauge seems to work independently of the other three small gauges, but all four will randomly go dead and come back
  • The speedometer and tachometer will randomly die and come back
  • Various lights come on and sometimes stay on for a while (sometimes the Airbag light, but most commonly, the Brake and ABS lights will come on at engine start and stay on for a long while)
  • a “ding” sound, usually when the fuel gauge goes dead and the “low fuel” light illuminates, but sometimes when only the Brake and ABS lights are illuminated
  • odometer displays “No Bus” sometimes at KOEO, and sometimes when the engine is running. When this happens for a long enough period of time, the overhead compass / trip meter / thermometer will display dashes instead of the temperature or MPG

The air conditioner compressor not engaging. This hasn’t happened in a while, but was happening a lot during our trip to Tucson in May 2015.

The rear right power window stopped working. It just stopped working from the driver’s control panel and hasn’t worked since. Also, the auto function for the driver’s side window worked when I first got the truck but no longer does. I’m not sure when that broke.

 

Along with these symptoms, I tend to see a P1652 code set in the computer at all times. It will come back immediately after clearing, though the Check Engine light does not normally stay on.

I have not been able to establish any sort of pattern as to when or why these symptoms occur. They seem to be independent of whether the vehicle is moving or sitting still; whether was just started after sitting overnight in the cold or fully warmed-up and driving around in 100-degree Tucson weather.

The only possible pattern I have noticed is that when I am sitting still (in my driveway or at a stop light) and the gauge cluster goes crazy, often if I put the truck in gear and start rolling forward, the cluster will suddenly come back to life and appear normal, for a while anyway. This trick usually works, but not always.

 

I have done the following to try and fix these problems:

Unplugged the fan clutch. Seeing the codes P0483 and P0480, combined with things I read on Dodge forums, led me to believe that a bad fan clutch might be causing these issues. However, the symptoms are exactly the same regardless of whether the fan clutch is plugged in or not.

Note that on February 16, it was about 70 degrees outside when I drove home. I still had the homemade weather front between the condenser and the radiator, and after doing 80 MPH for five minutes, the temperature needle was almost to the red. I dropped it to 65 MPH (the temperature barely dropped at all the rest of the way home), and removed the weather front once I got home. I noticed that the engine was idling at 1000 RPM, presumably because the ECM was commanding it to do so because it was hot. I also noticed that the fan clutch was not engaged, despite the engine being very hot; however, once I removed the weather front and got hot air blowing past the fan clutch, the fan clutch did lock in (it really roared!) and the engine rapidly cooled down. The clutch then unlocked as it was supposed to. This happened with the electric connection disconnected, which confirms the clutch works just fine without it.

Cleaned all the ground connections I could find, and replaced some ring terminals. No difference in behavior.

Disconnected the two connections to the ECM and cleaned them thoroughly using contact cleaner. No difference in behavior.

Disconnected the two connectors that run across the top of the transmission bellhousing and cleaned them with contact cleaner. No difference in behavior.

Repaired some damaged-looking wiring in the fan clutch loom. I took it all apart, cut out the bad section, and soldered in new wire. No difference in behavior.

Replaced both batteries with two Wal-Mart EverStart Maxx 65s, after one tested bad at AutoZone. This was about $250, give or take. I didn’t want to have one new one and one old one. No difference in behavior.

Replaced the gauge cluster. Twice, actually: I first ordered the wrong part (56049834AG) which, although the eBay seller listed it as a 2003 speedometer, actually is not. The connectors are reversed from the correct part number (56045600AK), and when I plugged in the first replacement cluster and connected the batteries, the cluster fried (and a strange mechanical, pump-like sound came from the engine compartment).

Once I got the correct part (a 56045600AK from a junkyard in Texas), it worked fine, but didn’t solve the problem; the same behavior is happening with the replacement cluster. I’ll probably put the original one back in so that I can get my 200,000-mile badge. The replacement cluster only has 177k on it, whereas the original was at 199,700 when I pulled it out. Total investment about $175.

Replaced the Power Distribution Center (PDC), part number 68005474AB. I ordered this new from MoparAmerica for $400, plus $25 shipping. I removed the old one from the truck and took it completely apart, drilling out the three studs that keep it together, and examined all the solder traces. I saw visible signs of corrosion, which led me to think that surely the PDC was the cause. Nope. No difference in behavior after replacing.

Replaced the Front Control Module (FCM), part number 56051036AF. I also ordered this new from MoparAmerica, for $309.19, plus $8.75 shipping ($125 of that is a core charge). Got it installed last night and, while the cluster craziness seems to have greatly decreased in frequency, it is still happening.

So, between the PDC and the FCM, the entire Integrated Power Module (IPM) has been replaced, with no change in behavior.

I’m about $1200 into trying to fix this problem, so far, with nothing to show for it.

 

At this point, I suspect the ECM is a potential source of failure. I’ve found a test procedure which lets you measure the ECM’s resistance to ground; if it’s out of spec, the procedure says the ECM needs to be replaced. In a way, I hope it does, since that’ll finally be what solves the issue (and it’ll mean I don’t have to go module to module, or even through the entire wiring harness, looking for the problem). On the other hand, it’s going to be probably at least $550 for a replacement.

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