Bad grounds....
Thread Starter
|
New User
Joined: Jul 2019
Posts: 14
Likes: 0
Bad grounds....
Hey guys,
trying to to figure out an issue with the truck (74’ f250)
with the headlights off, turn signals work properly however if I press the brakes, the front parking lights come on along with the brake lights.
If I have the headlights on, the left signal works inconsistently and the right signal doesn’t work at all, it just lights up the indicator on the dash.
Obviously I have some kind of grounding/backfeeding issue, I just can’t figure out where from. I’ve cleaned the grounds in the taillight buckets as well as the front park light grounds. Can’t find a ground for the headlights I’m not sure if there is one. Any other obvious grounds I should be checking?
Thanks guys.
trying to to figure out an issue with the truck (74’ f250)
with the headlights off, turn signals work properly however if I press the brakes, the front parking lights come on along with the brake lights.
If I have the headlights on, the left signal works inconsistently and the right signal doesn’t work at all, it just lights up the indicator on the dash.
Obviously I have some kind of grounding/backfeeding issue, I just can’t figure out where from. I’ve cleaned the grounds in the taillight buckets as well as the front park light grounds. Can’t find a ground for the headlights I’m not sure if there is one. Any other obvious grounds I should be checking?
Thanks guys.
Senior User
Joined: Feb 2018
Posts: 108
Likes: 1
Check em all! Lol. When I had trouble with my lights doing crazy things, I ended up adding a grounding cable from the battery negative to the inner fender, replaced the cable from battery to engine block, and added one from engine to frame. Cured all my ills....radio cutting out, headlights flickering, blower motor crapping out. There should be grounds for the headlights themselves very near the lights themselves. Ford's love their grounds!
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
If the ground and starting cables are original they are 46 years old at this point, and the SAE bullet connectors and pin block connectors through the firewall, none of that has likely been cracked open since then. It's pretty amazing that the lights work at all if you stop and think about it. Have some new heavy gauge cables made up with decent quality terminals and replace 'em all.
A brass bristle brush and some kerosene will clean up the pins and receptacles in the harness and the firewall connectors. If the lights are screwy you can bet the starter, ignition & accessories aren't getting the juice they need either and the alternator amps are choked off. The frame is used as the major ground path for lighting, maybe a cable from a starter bolt will go there. Make sure the connection to the frame is clean and shiny bright, and tight. Coat with vaseline or NO-OX to keep the crud away.
A brass bristle brush and some kerosene will clean up the pins and receptacles in the harness and the firewall connectors. If the lights are screwy you can bet the starter, ignition & accessories aren't getting the juice they need either and the alternator amps are choked off. The frame is used as the major ground path for lighting, maybe a cable from a starter bolt will go there. Make sure the connection to the frame is clean and shiny bright, and tight. Coat with vaseline or NO-OX to keep the crud away.
Thread Starter
|
New User
Joined: Jul 2019
Posts: 14
Likes: 0
Cleaned up the grounds around the headlights and actually just replaced the headlight connectors all together. Upon doing more digging, I’ve learned that my turn signals are receiving power with the headlights on when the key is NOT ain’t the ignition. Is this normal? If the key is out, the turn signals have no power unless the headlights are on, at which point they receive power. They still don’t work with the headlights on, but the fact they are receiving power with the key out seems strange to me. I replaced the headlight switch as well and that didn’t fix it.
Thread Starter
|
New User
Joined: Jul 2019
Posts: 14
Likes: 0
Update:
think i I might have narrowed it down to the turn signal switch. Replaced all the wires and sockets up front no change. Pulled out the trailer brake controller, didn’t make a difference. Issue changed a little bit so now if I use either signal with the headlights off, both tail lights flash as if the hazards are on. Gonna replace the TSS and hope that does the trick. I’ll fill in the thread when it comes in on Saturday.
think i I might have narrowed it down to the turn signal switch. Replaced all the wires and sockets up front no change. Pulled out the trailer brake controller, didn’t make a difference. Issue changed a little bit so now if I use either signal with the headlights off, both tail lights flash as if the hazards are on. Gonna replace the TSS and hope that does the trick. I’ll fill in the thread when it comes in on Saturday.
Thread Starter
|
New User
Joined: Jul 2019
Posts: 14
Likes: 0
Trending Topics
Senior User
Joined: Feb 2018
Posts: 108
Likes: 1
What you found under the dash is the high beam switch...it is normally mounted on the floor and activated with your left foot. I hate chasing down electrical gremlins. I'm guessing you still have a bad ground or bad wiring job done by PO.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
I'm assuming the PO had something spliced into the high-beam circuit there for one of the lights. Maybe some driving lights?
You should re-connect the two broken Green w/black wires before doing anything else.
Well, not before doing some testing of course, but if nothing else works, that's a broken circuit to one of your headlamps.
The Red w/yellow wire is 12v to the floor switch when the headlight switch in the dash is pulled to the 2nd position.
The Green w/black wires are for the high-beam lamps and the Red w/black wires are for the low-beam lamps. One of your high-beams is missing...
Did you check your bulb filaments with an ohm-meter to see if the lights were working? You could be dealing with multiple issues.
Paul
You should re-connect the two broken Green w/black wires before doing anything else.
Well, not before doing some testing of course, but if nothing else works, that's a broken circuit to one of your headlamps.
The Red w/yellow wire is 12v to the floor switch when the headlight switch in the dash is pulled to the 2nd position.
The Green w/black wires are for the high-beam lamps and the Red w/black wires are for the low-beam lamps. One of your high-beams is missing...
Did you check your bulb filaments with an ohm-meter to see if the lights were working? You could be dealing with multiple issues.
Paul
Thread Starter
|
New User
Joined: Jul 2019
Posts: 14
Likes: 0
Reconnected the high beam switch. Both high beams work as they should and even the high beam indicator on the dash functions as it should. I’ll go around the truck with my multimeter and check all the bulbs and sockets. I may just end up replacing all the bulbs and sockets. Some of them are a little crusty. Thanks for the input guys helps a lot 
Laughing Gas
Joined: Nov 2013
Posts: 1,207
Likes: 60
From: S.E. Louisiana;so far USA
Continue your checking/cleaning procedure. It seems like these problems happen more frequently on vehicles that have outside storage or live in some sort of corrosive environment, or both. Upon reassembly apply a bit of anti-oxidation compound to the connection. It's most likely due to sad connections or grounds.
Mountain Pass
Joined: May 2018
Posts: 133
Likes: 21
Did you try changing out the bulbs? I eliminate the ground problem by connecting a wire with clips on each end. Clamp one end to bulb socket base n other ens to frame. Works well when diagnosing trailer brake problems to. When I worked as a mechanic professionally the first thing was to insure a good ground. But have had a bulb filament drive me crazy. I generally try the easy stuff first.
Seems like a lot of times when chasing electrical problems that just taking everything apart while searching, and cleaning as you go solves lots of problems. Good luck man !
Seems like a lot of times when chasing electrical problems that just taking everything apart while searching, and cleaning as you go solves lots of problems. Good luck man !
Thread Starter
|
New User
Joined: Jul 2019
Posts: 14
Likes: 0
Well, I fixed it.
took all the bulbs out, (didn’t even clean them!), put them back in and everything worked. Gonna clean all the sockets and bulbs up and hopefully be on my way. Thanks a lot for all the insight fellas.
took all the bulbs out, (didn’t even clean them!), put them back in and everything worked. Gonna clean all the sockets and bulbs up and hopefully be on my way. Thanks a lot for all the insight fellas.
Thread Starter
|
New User
Joined: Jul 2019
Posts: 14
Likes: 0
Well, I fixed it.
took all the bulbs out, (didn’t even clean them!), put them back in and everything worked. Gonna clean all the sockets and bulbs up and hopefully be on my way. Thanks a lot for all the insight fellas.
took all the bulbs out, (didn’t even clean them!), put them back in and everything worked. Gonna clean all the sockets and bulbs up and hopefully be on my way. Thanks a lot for all the insight fellas.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
Great to hear.
This actually follows a good practice to use with these old rigs. Every once in awhile (every year or two maybe) remove and re-install every fuse in the panel. And maybe in your case even ever bulb in their sockets. This process of just removing and replacing breaks a "skin" of resistive corrosion for lack of a better word, and lets things work closer to their potential.
You'd be surprised how much buildup occurs on fuses and bulbs over time from sitting.
Paul
This actually follows a good practice to use with these old rigs. Every once in awhile (every year or two maybe) remove and re-install every fuse in the panel. And maybe in your case even ever bulb in their sockets. This process of just removing and replacing breaks a "skin" of resistive corrosion for lack of a better word, and lets things work closer to their potential.
You'd be surprised how much buildup occurs on fuses and bulbs over time from sitting.
Paul