• Dodge 1st Gen (1989-93)

  1991 Dodge W250 Electrical Mess

  Posted by cowboy on March 25, 2024 at 2:55 am

  I am trying to restore this oldie but goodie.  Its been an old farm truck used to farm and since the owner passed away 6 years ago its been sitting in a field here in Michigan.  This means the rust and critters have had there fun with the trucks wiring and this is my adventure at trying to figure it out.

  Some Electrical Issues I am dealing with at the moment include:

  1. Smoking wire at the positive terminal when I turn truck off in cold weather (assuming its the diesel heater relays but need to test)
  2. Emergency Brake says its always engaged
  3. ABS light is always on
  4. Taillights have no reverse light and turn signal and brakes not working
  5. Hazards don’t work

  How am I going to try and make sense of the mess that is under the hood?  I am going to leverage a couple of manuals which I link here

  90 Dodge Truck Diesel SM Supp (1)

  Then I just attack each one individually.  I found this pretty decent troubleshooting for the grid heater which I believe is the reason for #1 above.  I am thinking the relay is not kicking off so I’ll reference this youtube video to help me troubleshoot it.  Reason I’m thinking this is I didn’t have issues until it started getting cold here in Michigan which would trigger the grid heaters which is used instead of glow plugs.

  https://youtu.be/iB661SxBU3Y

  Now the next thing to troubleshoot is the Emergency Brake Light (#2) and the ABS light (#3) are always on

  

  Now I can make the ABS troubleshooting pretty straight forward.  Most posts I read say that its VERY common for the ABS module (found behind the glove box) to go bad which the default is to turn on the ABS light.  You can either unplug it or replace it.

  NEXT the BRAKE light could be on for many reasons but I’m assuming its the brake proportioning valve or the wire that goes to it.  At least thats where I am going to check first.

  

  In reference to the taillights (#4).  I ordered a new set of LED taillights so I don’t have to worry about the bulbs getting to hot or burning up the socket.  This just have the 4 wires you have to splice/connect to your truck and you are all set.

  

  And finally in references to the Hazards (#5) I believe I just need to replace the Hazard Flasher which I’m saving for last since I want the taillights in place before I go chasing that down.

  Missing hazard relay on the far right.  It should be to the right of that white horn relay.  its a 2 prong relay but need to make sure its compatible with LED turn signals…

  

  Also will need to replace the top left relay which is for the turn signals and it needs to be compatible with LED turn signals and currently looking at this relay on amazon

  

  Considering replacing my fusible links and the duck foot to make it easier to troubleshoot later

  

  A great Part1 and Part2 video on how to do this below.  Some parts you’ll need that he references is found below

  • Blue Seas Safety Hub 150 – https://amzn.to/2uZQIx1
  • 40 & 60 amp MIDI fuses – https://amzn.to/2RSuJS1
  • 175 amp Mega fuse – https://amzn.to/2vInC5U
  • Mega fuse holder – https://amzn.to/3bdbcDo
  • Wire loom tape – https://amzn.to/2v7AiTi

  PART1

   

  PART2

   

  Of course this guys engine bay is WAY cleaner then mine

  • This discussion was modified 1 month, 1 week ago by  cowboy.

  cowboy replied 1 month, 1 week ago 1 Member · 0 Replies
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