Never underestimate the importance of a ground (1 Viewer)

[bikersmurf]

I drove my truck for the first time in too long. I'd swear I had electrical gremlins if I didn't know the source of the problem.

My windshield wipers stop working when I step on the brakes, hit a bump, or turn a corner. The front turn signals also light up when Braking. The hazards also do funny things when you step on the brake.

I thought I'd share this experience since some of you have (or may be) experiencing similar problems. When replacing the front fenders, I had to disconnect one of the ground wires. The turn lights weren't working so I reconnected it in a new location. Voilà, the lights are working (or are they).

Clearly from the problems I'm now having the new ground location is ineffective. Once this ground is fixed I'm sure the gremlins will die.

A couple of important grounds on a 74(and other) 40:
Harness to right front fender
Harness to inner right frame rail beneath the fuel tank
At all the lights
Engine block to frame
And... Many more.

 

[rutbeer]

Don't forget the light switch grounds to the back of the dash. Or at least, my 74 did.

 

[piecemeal]

nice cattle pusher....

 

[Rambrush]

I was thinking musk ox pusher big moose on the loose etc

 

[bikersmurf]

The bottom corners get caught on the rocks

It's time to trim more off.

 

[65swb45]

Don't forget the light switch grounds to the back of the dash. Or at least, my 74 did.

...like the early dash blinkers! The licence light on the pre '74 40s grounded to the saloon doors or dropgate, but I've had multiple instances where I've had to provide a separate ground for that light.

Good thread.

Best

Mark A.

 

[fj hunter]

I eliminated the ...

chassis ground when i redid the whole system. Of course the ground is connected to the chassis, but each and every location and voltage application has it's own seperate ground line back to the battery.

additionally, all connections are soldered and shrink tube with hot melt covered.

you use a glue gun to apply a even coat of hot melt, let cool, then slid shrink tube over and re-heat ... provides a sealed junction.

 

[60fj25]

I agree that intermittent operation of the windshield wiper is probably a bad ground but could also be a poor input connection. However If stepping on the brake turns on something on a different circuit it is probably not a ground issue. It is probably having a wire from the brake circuit in direct contact with either a wire or contact of the other circuit. You step on the brake energizing the brake circuit and that also energizes the input to a signal light, which then also goes to a good ground.
I fought a problem where my trailer lights worked strangely. During the day, they seemed to work ok but when I turned on the headlights the brake lights (and the brake controller came on.). I found out that during the day if I stepped on the brakes the signal lights came on. It turned out that one of the brake/signal lights on the trailer was installed wrong and turned so both bulb contacts contacted both contacts in the light housing and it and everything else down the line would get energized from either circuit.

 

[Coolerman]

Two other major grounds to be aware of on older FJ's: The Alternator and regulator grounds.
The alternator MUST ground to the engine block. I would run a separate ground wire from the alternator to the block to ensure a good ground. Painted or powder coated mounting brackets cause a lot of grief.

The OEM regulator also has a ground that is the most important ground in the harness. This is a split ring terminal with TWO WB wires that grounds under the regulator mounting bolt. It supplies the ground for the entire front harness including headlights, front heater, wiper switch, VSV and the alternator. Note the ground wire from the regulator to the alternator is NOT the main alternator ground. If the alternator looses it's main ground to the engine this wire can burn up trying to act as the main ground.

 

[bikersmurf]

Floating ground

I agree that intermittent operation of the windshield wiper is probably a bad ground but could also be a poor input connection. However If stepping on the brake turns on something on a different circuit it is probably not a ground issue. It is probably having a wire from the brake circuit in direct contact with either a wire or contact of the other circuit. You step on the brake energizing the brake circuit and that also energizes the input to a signal light, which then also goes to a good ground.
I fought a problem where my trailer lights worked strangely. During the day, they seemed to work ok but when I turned on the headlights the brake lights (and the brake controller came on.). I found out that during the day if I stepped on the brakes the signal lights came on. It turned out that one of the brake/signal lights on the trailer was installed wrong and turned so both bulb contacts contacted both contacts in the light housing and it and everything else down the line would get energized from either circuit.

Electricity will always take the path of least resistance. Before I relocated the growing to an iffy location the electrical was working properly.

I didn't mention that the left flasher also blinks when the right signal is flashing...

Bad grounds will mess you up every time.

 

[bikersmurf]

I've now run a new ground wire from a good ground to the wiring harness ground above the right fender (now fiberglass). Wipers are working properly, all lights bright and working properly, and other electrical problems are gone.

 

[psreno]

I know this may sound stupid, but I'll throw it out there just to cover your bases -- so long as you don't ask me why this comes up.

Make sure the wiper wire isn't dangling down behind the brake pedal. Doesn't necessarily have to be the wiper wires, but you could be pulling a hot wire across the other wires coming off the fuse box down there when you fully depress the pedal. Make sure there isn't anything caught in the return spring etc.

It may help if you have someone step on the pedal while you look up under with a flashlight.

 

[bikersmurf]

Update. Things have all been working well until today.

To add to the list of weird and supposedly unrelated things: The electric fuel pump turns on and off when the Hazards flash (when it is off), the wipers stop at random, various lights start and stop working/flashing.

All of these systems ARE related, they share a common ground.

I found that the new ground wire I added had come loose. Tightening it made the problems go away (again). I also think I need to clean ALL of the ground connections on the vehicle (another day though).

Also, for another day is a complete new wiring harness. That will have to wait till the addition on the house is finished and I can get the 40 back in the garage.

My 40:

 

[DSRTRDR]

that is the one advantage of the aftermarket harnesses: they do not ground to a common circuit, but each device has its own separate ground - makes it easier to trouble shoot

well, except the brake-hazard-blinker circuit, which you must recreate to Toyota style for the OEM switches to work

 

[MoCoNative]

...like the early dash blinkers! The licence light on the pre '74 40s grounded to the saloon doors or dropgate, but I've had multiple instances where I've had to provide a separate ground for that light.

Good thread.

Best

Mark A.

I liked the disco effect the license plate light provided on a rough road. As the hinges of the rear doors rattled the light would flicker and change brightness, it was awesome

I too added a ground wire to the light housing and ran it back over to the backup light ground, cured the strobe effect out back.

Speaking of funky grounds on the back, ever see the defrost switch light up on the dash of an FJ-60 cause the dome light switch in the rear push button is trying to find a ground and goes back through the defroster lines and into the switch. That's a really cool effect because of no ground wires on a hinged door.

 

[Coolerman]

I usually add a separate ground for each light of the rear harnesses I make. There are two options for this:
One, I terminate the ground wire with a ring terminal that the end user attaches to the light housing via mounting bolts or some such.
Two, I terminate the ground with a bullet connector (or what ever connector the end user specified) and provide a matching connector with a short piece of wire that the end user solders to the housing. This option allows for easy removal of the light and guarantees a good ground to the light.

 

[CruisinMT]

Speaking of funky grounds on the back, ever see the defrost switch light up on the dash of an FJ-60 cause the dome light switch in the rear push button is trying to find a ground and goes back through the defroster lines and into the switch. That's a really cool effect because of no ground wires on a hinged door.

the 89 FJ62 we had did that exact thing. very strange. fan would come on too and when you turned on the rear dome light. never figured that one out before we sold it though.

 

[Mark W]

I agree that intermittent operation of the windshield wiper is probably a bad ground but could also be a poor input connection. However If stepping on the brake turns on something on a different circuit it is probably not a ground issue. It is probably having a wire from the brake circuit in direct contact with either a wire or contact of the other circuit. You step on the brake energizing the brake circuit and that also energizes the input to a signal light, which then also goes to a good ground.
I fought a problem where my trailer lights worked strangely. During the day, they seemed to work ok but when I turned on the headlights the brake lights (and the brake controller came on.). I found out that during the day if I stepped on the brakes the signal lights came on. It turned out that one of the brake/signal lights on the trailer was installed wrong and turned so both bulb contacts contacted both contacts in the light housing and it and everything else down the line would get energized from either circuit.

Nope... having other circuits energize when the brake lights are activated is a classic sign of poor grounding for the tail lights. The current back feeds via the common base of the bub which would normally be grounded. If it is not, due to corrosion or any other reason, the the current travels backwards through other circuits to reach ground.

The is almost a certain indicator of bad ground.


Mark...

 

[bikersmurf]

If you ever have unrelated things acting up, the ground is always the most likely problem.

Bad grounds will make weird things happen. Electricity will always try to find a way to complete the circuit.

 

[Varty Yo]

Hmmm very interesting. Im about to tackle a bunch of this on my 45 tomorrow