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After towing RV with bad batteries, truck blinkers...

groundhogy
Explorer
Explorer
... and brake lights doing weird stuff.

Turn signals act like a light is burned out. They blink real fast. Both sides.
Sometimes they blink a little slower, then pick up speed.

If blinker is on, and then you brake also, the blinker freezes up and stops blinking.

If you go behind the vehicle, the turn signal and brake lights can be seen, but are dim.
23 REPLIES 23

bucky
Explorer II
Explorer II
Try this to isolate the affected circuit. Start pulling fuses one by one for the lights involved. Put the fuse back you just pulled before pulling the next one. Hopefully that will give you a glue.
Also since you are in PA where rust is a "thing" a frame harness may have been compromised.
That generation Ford had corrosion issues at the top left corner of the windshield allowing leakage down onto the components behind the dash on that left side. That's where the headlight switch is. Ohm your switch or try a new one. Maybe you have a pal that would let you try his switch. You don't have to pull yours, just pull the connector down to plug into the test unit.
Do the 4 ways work correctly? Do you have a trailer connecter in the bed?
Something is back feeding either due to a bad or missing ground or a bad switch somewhere but the delay puzzles me. I hate these type of problems and a lot of techs just throw parts at them and hope they get lucky.
Puma 30RKSS

groundhogy
Explorer
Explorer
Brake controller removal did not change anything.

CLUE: So I pulled the tail light and had the bulb out to observe.

It is a dual filament bulb. Top filament for blinkers and stop. Bottom filament for nighttime tail lights.

When you turn on the turn signal the blinker speed is normal, you correctly see the top filament blinking.
But then you see the bottom filament start to light up . And the blink speed goes up.

bucky
Explorer II
Explorer II
Unplug the brake controller and see what you have then. I've had that issue. I forget the brand but they sent me a new one overnight at no charge.
Puma 30RKSS

groundhogy
Explorer
Explorer
updated more accurate symptoms
-Blinkers.. both L/R blink
-Breaks... seem ok unless maybe dim?
-Running tail lights.. none in back
-Reverse lights .. none
-License light... ok but flickers with turns

-Blinker speed... Starts almost normal speed and speeds up like when a bulb is out.


I am capable of fixing this, but I need drawings and I am having a hell of a time finding Schematics or Assembly drawings showing component locations.
Still plodding away at this.
F-250 2003 7.3L

This seems to be a single point type of failure. Like one point that is common to each of these unrelated circuits has failed causing multiple failures.

Grounds seem to be distributed at each bulb, so the chance of a bunch of grounds lifting at once is small it seems to me.

Maybe a supply voltage wire might be common to all of these circuits?

Or yes, maybe a wire got hot?

Or a wire was already corroded from age and opened up with high current?

So, I have discovered that the truck batteries and the trailer batteries are connected together directly it seems when you plug in. So the truck was probably heavily charging the trailer batteries during the towing.

Like.. the back up lights and also the night time tail lights are both out.
They should have NOTHING to do with each other. SHould be totally different wires and circuits...

Front lights all good. Look fine.

NamMedevac_70
Explorer II
Explorer II
Sometimes you have to bite the bullet like I recently did with truck electrical and start problems and take it to a AAA auto garage or Napa garage, etc. They kept the truck for two days before looking at it then fixed my problem in only several hours. I have a spare dodge ram so not too much hassle for me. I have time but not knowledge or patience to troubleshoot electrical problems even though i tried for a week. Cost was 170.00 dollars with senior, veteran and AAA discount. Unlike others Sierra Car Care center at Plumb lane and Lakeside Drive was polite and courteous about taking my money.

groundhogy
Explorer
Explorer
Yes. The problem remains after RV is disconnected.

Update on symptoms. My first post was relaying what my wife said as she was behind the vehicle.

So last night I went behind the vehicle and looked myself.

When you turn on full night lights, nothing. So when you are driving at night the tail is completely black.

When you put on blinkers, you get a faint fast blinking. The license plate lights will dim and bright together with the turn signal.

When you put on brakes, both back lights blink just like it's a hazard except dim.

Front lights seem unaffected except they blink more rapidly.

jdc1
Explorer II
Explorer II
wa8yxm wrote:
Bad ground connection on lights or between tow vehicle and trailer


And check your FRONT turn signals.

mr_andyj
Explorer
Explorer
clarify all this...
You say, after. Do you mean after towing and after unhooking and then driving the truck with no trailer then things do this, or it does it when hooked up?

wa8yxm
Explorer III
Explorer III
Bad ground connection on lights or between tow vehicle and trailer
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times