I swapped my 1998.5 drivetrain and engine wiring harness into a 2001 1500, all fuses and relays are good, I only have reverse, turns and hazard lights the rest of the lights do not work including dash, tail, running lights and headlights. The high beam indicator on the dash always stays on no matter what. I have ground to all lights just no power any ideas?

Hit,

 

You should not have grounds to the headlamps unless the headlamp switch is in the ON position.  the headlamps have constant 12v+ from fuses B and C in the PDC.  (this is from the 2001 FSM)

 

 

GL  HTH

Hag

 

So it seems like a possible multifunction switch and possible wiring issue for the positive side of the lights? Today while working on it the turn signals have now stopped as well so now only brake lights

 

 

Hit,

 

The multi-function switch can be a problem, but you should still get low beam headlights without it.

 

We have a great selection of .pdf manuals here.  Look at the top tabs.   There is "forums", " articles" , "downloads"

 

Click the download section, then look at the list and pick "dodge ram factory service manuals"   Pick your years and save them.  

 

Section 8w is the electrical section.  That will be your best friend.  

 

I think the first thing to figure out.  Is your dash a push pull headlamp switch or twist knob?  were any of the iterations push pull headlamp?

 

On the turn signals, if they did work and now not, it is probably the flasher unit.  Our flasher unit is not the old heater type, but an electronic timer thingy.  It is VERY susceptible to damage from funny voltages.  It will do things like fail leaving one turn signal on all the time.  So at the moment, keep searching for the main problem. 

 

Hag

I believe you are mating two incompatible wiring harnesses. The '98  was set up for "+" switching of the lights (constant ground at the lights) and the 2001 is set up for "-" switching of the lights (constant positive at the lights).  On a '98 the common terminal on the head lights is connected to ground "-" and on a 2001 the common terminal is connected to positive "+".  I think you need to do some conversion wiring.  It seems like you have a mismatch of feed to the switch and what is needed to complete the light circuit (sending a ground feed to a grounded light = no circuit)

 

I believe the switching changed in 2000.

 

I ran into a snow plow headlight issue when moving my plow from a 1998 to a 2002 Ram.

 

Joe

Edited May 31, 20204 yr by Joe_Pool
To add information

That sounds accurate, I pulled the light switch out of the dash and ran power to the wire that goes to the lights, forgot the color of course but do you know which wire would be the current “ground feed” that I could cut and change it to a “positive feed”

 

So i found the issue to be as stated before the headlights are ground controlled fixed, still no turn signals but today I was driving around and got a no bus on the dash and the truck will not rev past 2000 rpm. I have no clue where to even start. I’ve cleaned all the grounds and checked all connectors.

Hit,

 

No bus means there is no communications between the computers (PCM, ECM and cluster)  you will need to troubleshoot that system.  It could be as easily as the cluster not communicating, but that usually doesn't limit engine ( you can drive with no cluster installed)  since you are losing power it sounds like PCM ECM communication issues.

 

GL

Hag

Edited June 10, 20204 yr by Haggar

So after some digging, I finally found the issue, the vp44 finally threw a code. P0251 checked all the wires, all came out good. Sent it back for warranty Monday to blue chip and I should hear back soon

Hit,

 

Glad you finally got something!  Its crazy when it just won't work, but there is no direction to help you figure it out!

 

Hag