Crazy electrical issues 1990 B II 2.9 Auto trans. manual hubs.

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All lights work, but RH Side flashes slower...?...pull headlight switch out for running lites, RHS stops flashing.....But, Wait, that's just the begining. Step on brake, works, but less volts on RHS.....L. Turn signal on, L. brake lite goes out, & back-up lites get stray voltage, like 2 or 3 volts.......R. turn signal on R. brake lite goes out [no stray voltage to back-ups ]......Pull running lites on [ key off ] step on brake, R. tail lite goes out, also the plate lites go out, & back-up lites come ON ! ......Put in reverse, [ key on ], back-up lites come on, not bright on RHS. Stray voltage in tail lites, about 2 or 3 volts....Step on brake now, L. on, R. about 6 volts...R. back-up goes out, & plate lights brighten.......Key off, step on brake L. lite bright, R. 5 or 6 volts., back-up lites 3 or 4 volts, plate lites, 3 or 4 volts... I have eliminated headlight SW. Turn indicator SW, Ignition SW, took out 4 relays, dissconnected altinator, taken every fuse out, swapped bulbs R to L. inspected wires, changed the flasher, & still have the problem ?
 
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Tiha

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Sounds like a bad ground. When you turn on your headlights there is not enough ground so it basically keeps the flasher on.

Could be front or rear.

I suppose could be a bad bulb too, much thinner chance of that. But I would start by pulling the turn signal bulbs and start adding back one at a time.
Does one of the marker light/turn signal assemblies seem brighter than the others with the headlights and flashers on? If so I would start there.
 
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Sounds like a bad ground. When you turn on your headlights there is not enough ground so it basically keeps the flasher on.

Could be front or rear.

I suppose could be a bad bulb too, much thinner chance of that. But I would start by pulling the turn signal bulbs and start adding back one at a time.
Does one of the marker light/turn signal assemblies seem brighter than the others with the headlights and flashers on? If so I would start there.
I do not think any od this is ground dependent, and certainly I get full voltage when the lites work properly, like on the RHS.
 

miesk5

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Yo 4 speed,
Welcome!
As Tia advised, Troubleshooting; "...If you have a problem when turning on one circuit it causes another to come on partially (dim lights, etc.), check the ground for the part or system that was turned on first. i.e., if you press the brake pedal & the parking lights turn on partially or fully, check the brake lights' ground; This is caused by current going through brake light bulb filaments & finding a ground in the parking lt. system instead of its own ground..."
 

miesk5

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Yo Jimmy,
Hopefully someone here can provide more ground locations and wiring diagrams for you.
Also contact your local library for possible access to on line AllData or on line Chilton.
 

Tiha

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The grounds you cleaned go from the light sockets to the body?
Then there should be a body to frame.
Also a body to battery.
The backup lights getting stray volts really points to bad ground someplace.

If it is none of those. Then you are looking at a pinched or melted harness someplace.
 
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The back-up lites will work fine, as long as nothing else comes on. It is Not like they do not work, they do. They will get the stray volts, when the tail lites are turned on. ? Crazy things happen, like when the brake gets applied.
I have a Great ground, just that the problems are associated with the R.H.S. That has to mean something ? when the back-up lites do get
the stray volts, like 2 or 3 volts, it is BOTH ?
 

Tiha

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We run liftgates on the back of van trailers. When the motor ground starts getting rusty or bad operating the liftgate will light up the tail lights on the trailer.

That ground voltage is looking for someplace to go, that is where you stray volts are coming from.

Here is maybe another way to help troubleshoot it.

Take a set of jumper cables. Connect from the negative on the battery to one of the ground points you just cleaned up. See what that does.
Just connect the black cable, ignore the red one.

basically you are simulating running the ground from the light directly back to the battery.

if that fixes the problem, you still have a bad ground.

If it makes no difference then a ground is not your problem.
 

johnnyreb

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Since the Bronco has a aluminium hogs head. It might be like my Fairlane. When I,d park it during the winter and spring I,d get ready to run it. I,d have to take the starter off and clean it really good and also the hog head. Its some you might want to check out.Since the motor is attached to the transmission. Hogs head is the bell houseing in case some people do not know what it is. Good luck.
 

MT Phil

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All lights work, but RH Side flashes slower...?...pull headlight switch out for running lites, RHS stops flashing.....But, Wait, that's just the begining. Step on brake, works, but less volts on RHS.....L. Turn signal on, L. brake lite goes out, & back-up lites get stray voltage, like 2 or 3 volts.......R. turn signal on R. brake lite goes out [no stray voltage to back-ups ]......Pull running lites on [ key off ] step on brake, R. tail lite goes out, also the plate lites go out, & back-up lites come ON ! ......Put in reverse, [ key on ], back-up lites come on, not bright on RHS.I Stray voltage in tail lites, about 2 or 3 volts....Step on brake now, L. on, R. about 6 volts...R. back-up goes out, & plate lights brighten.......Key off, step on brake L. lite bright, R. 5 or 6 volts., back-up lites 3 or 4 volts, plate lites, 3 or 4 volts... I have eliminated headlight SW. Turn indicator SW, Ignition SW, took out 4 relays, dissconnected altinator, taken every fuse out, swapped bulbs R to L. inspected wires, changed the flasher, & still have the problem ?
I had a similar problem, but not the exact same. I changed almost everything. It ended up being a rear light bulb that had one side of the element fell down on the other element shorted out and did all kinds of weird crap with the lights. It was on a 76 Ford PU 1157 bulb. Good Luck!
 

johnnyreb

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I had a similar problem, but not the exact same. I changed almost everything. It ended up being a rear light bulb that had one side of the element fell down on the other element shorted out and did all kinds of weird crap with the lights. It was on a 76 Ford PU 1157 bulb. Good Luck!
If the bulbs have a yellow end--brassppit is American made. If it is silver--it is made in CHINA AND THEY ARE JUNK. GO TO A JUNK CAR AND GET THE BULBS FROM IT.
 

johnnyreb

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All lights work, but RH Side flashes slower...?...pull headlight switch out for running lites, RHS stops flashing.....But, Wait, that's just the begining. Step on brake, works, but less volts on RHS.....L. Turn signal on, L. brake lite goes out, & back-up lites get stray voltage, like 2 or 3 volts.......R. turn signal on R. brake lite goes out [no stray voltage to back-ups ]......Pull running lites on [ key off ] step on brake, R. tail lite goes out, also the plate lites go out, & back-up lites come ON ! ......Put in reverse, [ key on ], back-up lites come on, not bright on RHS. Stray voltage in tail lites, about 2 or 3 volts....Step on brake now, L. on, R. about 6 volts...R. back-up goes out, & plate lights brighten.......Key off, step on brake L. lite bright, R. 5 or 6 volts., back-up lites 3 or 4 volts, plate lites, 3 or 4 volts... I have eliminated headlight SW. Turn indicator SW, Ignition SW, took out 4 relays, dissconnected altinator, taken every fuse out, swapped bulbs R to L. inspected wires, changed the flasher, & still have the problem ?
I done alot of the too. Then I ran one wire for my back up lights-----to the switch on the transmission. The a hot wire off the switch--whit the switch in the start position. --Follow the wire OFF of the transmission .Up the firewall . It will come up about the center of the fire wall.It will have a plug. Un hook it and run you NEW wires to it. I,ll see if I can find some pictures
 

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