1978 FJ40 - Lights gone bonkers

[itxpt]

Got an issue where when turning on the turn signals, all lights flash on all 4 corners, like if I turned on the hazards. When I press the brake pedal, all four corners light up. All lights seem to function as far as lighting up, but not behaving as they should. It seems the flasher is working but is somehow controlling all the lights. Not sure where to look at this point.

 

[pb4ugo]

When weird things happen it's usually a ground issue.

 

[charliemeyer007]

Well it sounds like there is a short in the wiring somewhere. You need the proper wiring diagram for you rig. There might be free downloads or the Haynes manual will have one.

Your unit is like 50 years old. Take every connector/bulb socket apart - clean and inspect the contacts plus look at the wire where the terminal is crimped on - corrosion can crawl under the insulation. With battery disconnected pull the fuses and clean the contacts - 30 cal bore brush works well on glass tube fuse contact. You can unbolt the fuse box ad do the backside too.

Maybe you have a trailer hookup - a short here could cause brake/turn signal problems. The turn signal switch and hazard switch can be taken apart and rebuilt, some can be bought new.

LED upgrades aren't exactly plug and play usually

Land Cruiser Factory Service Manuals (FSMs)

Factory service manuals (FSMs) for your Toyota Land Cruiser ! From the 1950s to the present!

www.cruisercult.com

 

[South Texas 97]

@Coolerman 's site is the place to look for the diagrams
Cruiser Wiring - http://globalsoftware-inc.com/coolerman/fj40/wiringmainframe.htm
and find your year on the list at the top center of the page. (Link to wiring schematics by year)

I have made copies at 11x17 or larger, and then get them laminated - you will never regret having several copies, and at least 1 laminated.

All the indicator wiring goes via the hazard switch. In addition to the above excellent suggestions, you may decide to take out the hazard switch and give it a good cleaning.
I added separate grounds from inside the indicator housings back out to the frame.
Check under the pax side frame rail were the wiring runs to the back of the truck, mine was working, but completely toast - a fire waiting to happen when you include the reverse light. Check that wiring in detail - you will find also a ground half way along the frame, where the fuel tank level sensor grounds to the frame. Remove, clean and reconnect that ground as well.

As stated also, if you have LED's or the PO put in LED's - this will drive your flasher nuts. they do not have enough resistance.

Let us all know what you discover.

 

[itxpt]

@Coolerman 's site is the place to look for the diagrams
Cruiser Wiring - http://globalsoftware-inc.com/coolerman/fj40/wiringmainframe.htm
and find your year on the list at the top center of the page. (Link to wiring schematics by year)

I have made copies at 11x17 or larger, and then get them laminated - you will never regret having several copies, and at least 1 laminated.

All the indicator wiring goes via the hazard switch. In addition to the above excellent suggestions, you may decide to take out the hazard switch and give it a good cleaning.
I added separate grounds from inside the indicator housings back out to the frame.
Check under the pax side frame rail were the wiring runs to the back of the truck, mine was working, but completely toast - a fire waiting to happen when you include the reverse light. Check that wiring in detail - you will find also a ground half way along the frame, where the fuel tank level sensor grounds to the frame. Remove, clean and reconnect that ground as well.

As stated also, if you have LED's or the PO put in LED's - this will drive your flasher nuts. they do not have enough resistance.

Let us all know what you discover.

so the back brake light and the front turn signals have been replaced with LED. All the other suggestions I don't think are an issue because everything functions as should except for the wonkiness. would a new flasher or a more modern one support the LEDs better, the one in it definitely looks like it's original.

 

[South Texas 97]

yes, if you are keeping the LED's then a new flasher is in order - @Coolerman has a small kit to change the flasher over if I recall correctly.

Although this does not explain the brake pedal turning on all the flashers. or is it just turning on the running lights. Either way that would be a short somewhere.