good evening guys so i have a 1990 dodge cummins 3/4 ton non ic bone stock besides air intake.
the issue im having is severely electrical.
( only the key is on truck is not running same issues when trucks running )
when i pull the headlight switch just enough for dash lights or pull it all the way out for the headlights to come on i have no brake, running, reverse lights at all. the turn signal bulbs as well as 4 ways will burn very dim but never flash. without the headlight switch pulled out to the on position i have bright turn and four way signals front and back, no brake lights, no reverse. moving the tilt column does not change anything!

this is the CRAZY part without the headlight switch in the on or turn signal switch on either way, meaning the headlight switch is pushed in(off) and the turn signal switch is in the neutral position in the middle on the column an 4 way switch not engaged but the key on! the turn signal relay ( not the 4 way relay) still clicks at the fuse box as if turn signals are on but no lights on dash blink it will only stop if you pull the relay or unhook the battery. it will not stop by turning the key off
(note all of my dash lights work turn signals, 4 way high beam)

the other CRAZY part is with just the key on when you pull the headlight switch on or push it in to off or turn the signals on the volt meter will go jump down and back up every time they flash or you pull the headlight switch on.

(note there is no voltage meter wiring or alternator wiring to the battery due to waiting on my 1 wire alternator to come)

now i have replaced the following (NEW not USED) headlight switch, all fuses in fuse box, all 3 relays in fuse box, new bulbs, new bulb sockets ( front and back) checked all light wiring, checked current in fuse box receptacles they have current, replaced the 4 inline fuses under the hood right at the fire wall with new in line fuses 1, 60amp 3, 40 amp going into a wire block and a 4 gauge wire coming out the other side of the block straight to the battery. new battery, all grounds checked and cleaned.
i do have a new turn signal switch i haven’t installed yet.

hopefully some of you can help with this. thanks

 

Install that turn signal switch you have for it.
Make sure you have a '89/'90 style switch, not the later and more common '91-'93 multifunction switch.

If you need the correct switch let me know and I can check my 1st gen parts stash.

 

Keep in mind that everything on 91 and older trucks goes through the key switch, and they fail slowly with time. I would suggest replacing it and put all your high load items on relays off the battery. Had to do that with my 91.5.

 

i appreciate your feedback, i ordered the best turn signal switch rock auto offered and it’s supposed to be for a 1990 with tilt steering

 

cougar) you mean replacing the key switch it self and i’ve read some about relays but thats something i’m not extremely familiar with. do you basically run a hot wire from the battery to the fuse box with a relay in between or the hot wire would be ran from the battery else where?

 

A '90 with tilt should be the GM/Saginaw column. The ignition switch is then mounted on the column tube under the dash.

Might be an idea to unplug the column harness and see if the headlights behave on their own?

 

u2slow that is correct the ignition barrel is on the side of the column but when the key is turned on it moves a lever on the driver side of the column down to a switch i’ll give that a try

 

when you replaced the bulbs did you check to make sure the sockets were grounded? A bad ground in the tail lights will give some strange behavior.

 

edwinsmith) when i replaced the bulbs i replaced new bulb sockets along with them, i also grounded each ground wire from the new socket spliceed into the harness ground wire to a clean spot on the body so i knew they would have a good ground, everything i have mentioned above has been done recently so no weather has gotten to anything to make any connections rust or corrod and it hasn’t seen the road yet

 

Look in the FAQ section. You will finf information there.

 

cougar the wiring will be kept factory as it can be so if worst comes to worse ill remake a new harness myself

 

There is a harness wire under the dash that grounds to the cab close to the steering column. That will create all kinds of problems. Is it good?

 

BHD) so far i have not found any ground around or near the steering column

 

Here it is called oit in the FSM..

I used a 1990 dash harness in my '85 RoadTractor build. I used the clutch/brake rod retainer for the ground attachment.

 

If you did check all your grounds, try checking contacts at bulkhead- had similar issues and corrosion definitely occured there on mine.