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Only lights that work are Headlights - where to start???

RootBreaker

RootBreaker

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Ok so lets start here - I searched and didnt find what i needed ....

googled and found schematics, etc.. and ideas on what to try so I will list what I have tried and where to go from here...

Truck worked before i tore it apart to put 8.1L in

truck starts and runs
wipers and squirters work - my yesterday fiasco that was an all day ordeal but finally done and better than it ever has been since 89...
horn works
radio works (well no speakers but it powers on lol)

issue:
No Hazzards
No Turn Signals
No Brake Lights
No Reverse Lights
No Parking lights

bulbs - all LED except brake lights/reverse light triple bulb - but like said if one bulb out, then left or right should work...
Rear grounds - didnt touch them so dont see that as an issue... but for sakes... later today I will pull harness apart and jump 12v to each one (excluding ground lol) to make sure bulbs light....and grounds good

Troubleshooting so far
Grounds - My father is a mechanic (getting older and in bad shape so called him to chat to see how he is doing then lightly hit truck question) and he said... if headlights work, cab is grounded fine...

BUT.. lets go over grounds..
dual batteries...
cab to drivers head
cab to drivers battery
drivers battery to frame
drivers battery to radiator support where there are 3 other wires
passenger ground to passenger block (making sure engine is grounded for ecu sake!!!!!

Fuses - all fuses are fine... test light, lights up on each side of every fuse in the block

Brake pedal switch - popped connector and had power on one side, jumped wire and no lights out back


so what I am thinking next...

take brake switch off again, find side that is hot.... take other side and follow wire back to see where it goes... then see and figure from there????

check headlight switch
- red should be constant power and on google said headlights ONLY - which work so i can verify that...
- orange has 2 wires.. should be hot all the time as well


what else can i check here? like said it all worked but then stopped immediately with only removing front clip, so i do not see headlight switch as bad...


thoughts and ideas?????
 
Fusible links that were on starter before? Did one blow or get left off? Also the little power junction block on the firewall. I can look at schematics when I get a chance and narrow it down better. What year is this thing?
 
Truckman4life said:
Fusible links that were on starter before? Did one blow or get left off? Also the little power junction block on the firewall. I can look at schematics when I get a chance and narrow it down better. What year is this thing?
Click to expand...

hah that is the great part.. what year? you mean what YEARS!!!!!!! been wrenching on it since 1989!!!!! and used 8 trucks initially to build it.. since then 3 more swaps between engines, cabs, front clips...


that power junction on the firewall is not in use...

the fusable links from starter are there and are fine... i have power to the cab, truck runs too....

so.... the harness is this..

ez wiring 21 - https://www.ezwiring.com/product-page/ez-wiring-21-standard-wiring-harness

it has to be something stupid...
 
Head lights ground to the core support not the cab. Do you have ground from engine to cab, I think you are missing a good ground to the cab, to have all rear lights out. Do the front lights beside the headlights work?
 
The brake circuit runs out of the brake light switch, up into the column to the turn signal switch, and back out on the yellow and dark green wires to the brake lights.
 
frankin5 said:
Head lights ground to the core support not the cab. Do you have ground from engine to cab, I think you are missing a good ground to the cab, to have all rear lights out. Do the front lights beside the headlights work?
Click to expand...
20210705_182520.jpg

hit hazards and only light solid... nothing else...
 
flasher is bad. So you have power to other lights. check both of the flashers.
 
omg lol

lol somethin is wacked.. i press brake pedal and dash lights come on!!! lol

fyi tied lund lights to gauge lights so can dim them.. press brakes and they come on too!!!!
 
My turn signals did the solid light up thing when there was a ground off at the core support right above the headlights.
 
wow.. just wow.. truck worked b4 pulling front clip and doin motor swap...
issue..yall were right...
GROUND

there is a spot a ground wire attaches to bed behind each tail light.. connect to each other and nothing else.... so i ran a wire from the back, all the way to drivers battery and boom!!!! ugh lol...

got few other issues I am gonna handle but wow...



so somehow i lost bed to frame ground...
 
Are the grounds on the back side of engine connected to the cab? This is where the the cab and body get its ground.
 
frankin5 said:
Are the grounds on the back side of engine connected to the cab? This is where the the cab and body get its ground.
Click to expand...

yes the engine and cab are grounded together...
but
bed doesnt touch the cab.. thus why would it be grounded from that?

fyi - i figured the bolts through bed are metal and into frame and bed... thus should ground it fine... even though i have a body lift. well guess somewhere ground stopped!!!
 
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