Did Toyota make a deal with Lucas Lord of Darkness - another electrical Flasher issue

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Sep 9, 2011
Jan '71 FJ40

Problem - No Turn Signals (were intermittant before), No Hazard Flashers.

What I have done - New Bulbs and grounds all lights, replaced both rear lights (Toyota OEM).

What Happens now -
1. Pull Hazard - get double click, no lights
2. Running lights and headlights OK
3. Pull Hazard with brakes on, Dash lights come on
4. Brake lights work - except when turn signal switched, the side turned goes off if the brake is on

Any ideas, I have some electrical knowledge, but not much. I am trying to avoid pulling the heater, can't get to hazard switch without pulling.

So did Toyota get their electrical info from Lucas Electric. The last car I had that was this weird electricaly was an MGB (I know it was stupid but I was young)
In a later model, I think I can get to my hazard switch by removing the ash tray.

Did you sand all your grounds? Inside the front housings, fuses, etc? It's not too hard to clean the internals of the hazard switch and re-lube with some conductive grease. All the voltages for the blinkers and hazards flow through it.

You're going to have to learn about using a volt meter and get some long pieces of wire to use as test leads.
Does sound like an odd ground path going on. I understand the lucas reference, my other car is a lotus!
The light grounds are all clean fresh scraped raw metal. The front ones attach to the battery to frame ground.
I understand volts, amps but ohms are beyond me.
I took the ashtray out and could touch the hazard switch, but that is all. Couldn't get it out. Any tricks?
The logic of everything running through the hazard switch and then not being able to access it is crazy. Looking at some wiring diagrams there seems to be a fuse in there.
I have a 71 with only one flasher for both hazards and turns. Both are through the hazard switch. You have two hot wires to the hazards - one constant and one switched so hazards can work without a key but turns need the key. When hazards are pulled the hot is routed to the flasher, then back into hazards switch and out to all four corners. With hazard off and key on - the switched hot goes out to flasher, back into hazard switch, then back out to the turn signal switch input. There it sits until you activate the turns. When you do, you route the flashing voltage input to the correct side (this is in the turn switch now) and the left or right corners flash.

What you describe with the brake is correct. Foot on brake with no turns, both brake lights illuminate. When activate a turn with brake on the turn side should be flashing and the opposite side stays lit for brake.

You dont have flashing voltage to the input of your turn switch.

I would suggest you change the flasher - about a $5 part. 3 wires: ground, solid input, flashing output.

BTW the headlights/markers/headlight switch/dimmer switch - have nothing to do with flashers or turns or hazards. They are independent systems.

Check the flasher.
So, will a cheap tin can flasher replace the twin relay over designed Toyota one.
I would try a new flasher to see if that is the problem. If it is, then decide if you need to replace with OEM. There is a relatively easy way to test the hazard switch if it was out of the truck, but I don't recommend pulling it if we can figure out the problem with a few easy steps.

...and you have to get comfortable with Ohms. Its a measure of the resistance between two points. The two values that will be most important for most troubleshooting is "open" and "short". A short circuit will measure 0 ohms (some meters have a continuity setting with a buzzer - its looking for 0 ohms). If there is 0 resistance between two points, they are shorted together and are basically the same point - voltage applied to one is the voltage you will see at the other. The mechanical switches in a 40 simply short two pins or wires together internal to the switch with shorting plates that move when you push/pull the switch. This is important because out switches just "RE-ROUTE" voltage from one wire to another based on switch position - they are just traffic cops.

The other important Ohms value is for an "open" circuit - this is infinite resistance because it is telling you that the two point are not connected in any way. This might just be a blank display on your meter or some other such thing.

That's enough for most troubleshooting - a "true" ohms/resistance value is necessary when you care how much current is running in a system. Current (amps) and resistance (ohms) are related - they are actually inversely proportional, meaning to maintain a constant 12V, if the resistance goes down the current goes up, and vice versa such that current multiplied by resistance equals voltage. V=IR, where V is voltage, I is current, and R is resistance.

Sorry for the long lesson. But its good to have a feel for the basics.
Had a Triumph back in the early '70's .... never got use to the headlights going out every time I hit a pothole. :D
I have had a few "grounding" issues with my Toyota's but nothing came close to the issues on that fine British automobile.:)
Thanks Tim71. Your explanation of ohms helps. I have many meters but only used a minor part of them. I will go to Napa and get a flasher, hope that works, not looking to pull the heater at this time. I will need to rewire my 40 in the future. I have already removed what feels like miles of wires to nowhere from the PO.
Got the flasher - $6 part and $7 gas. Made no difference. While trying to see if I could get to the Hazard flasher switch (no luck) I keep pulling it out and pushing it in because I heard a click before. After doing a bunch of those, the hazards started clicking and working. Now if I move the switch 5 to 10 times the hazards work, but no turn signals (which were intermittant before - mostly not working). Looks like will have to remove the heater to get to the switch. How does the knob come off?
it was worth a shot... do you have one flasher or two. Mine has 1 and I have a wiring diagram to match, while others here swear that factory for 71 had two - a separate one for hazards and one for turns. I think we agreed that both were factory and maybe there was a mid-year change.

I suggest that if you go through the trouble to pull the switch, just replace with a new one from CCOT or SOR.

If the knob comes off, there is a small slotted set screw, then it unscrews from the shaft.

If you want to pull your old switch and test it with your meter we can walk through it. You can do it sitting at your kitchen table.
Now if I move the switch 5 to 10 times the hazards work, but no turn signals (which were intermittant before - mostly not working). Looks like will have to remove the heater to get to the switch. How does the knob come off?

I still think you can get to the hazard switch with some creative maneuvering. What you describe is exactly what happens when the hazard switch needs to be serviced, ie cleaned and re-lubed. You need to find some conductive grease. When you get to it, you have to bend tabs to get the cover off the switch mechanism. The inside is a bit complicated with little springs and stuff, but it's not impossible to understand, especially if you have a schematic.

The hazard switch has to take hot battery power to power the hazards when the ignition is off and it has to take switched power for the blinkers. Then it passes one or the other to the flasher, and then routes it to left, right or both circuits, depending on the switch setting. It's more complicated than you may want it to be.
This saga will have to be delayed for a while. Broke switch - 40 year old plastic ain't what it used to be. Need to order new switch. Switched over to installing my Trollhole carb.

Have a question though. If I understand correctly there are two power sources to the switch, one always hot (hazard) and only hot with ignition. Anyone know in the plug which wires to check for power. I would a least want to check that while waiting for the new switch. Best place to buy?
I think I got mine from CCOT. Need to check wiring diagram for wire colors assuming your wiring is original.
Hazard/TurnSignal Operation for a description of how the turn and Hazards work on a 71 with SINGLE flasher. Both power wires are GR. On the early 71's one of the fuses is inline and located above the heater in the harness. Later 71's and up had both wires going to separate fuses (switched and un-switched) in the fuse panel.
I'm not having any luck finding a hazard switch. CCOT and SOR do not list them any more. Any other ideas?
I had all sorts of flasher problems (turn and 4 way) with the stock mechanical flasher units. I finally switched over to a solid state flasher unit used for LED lamps as they have a very low amp draw to start it going, 0.01 amps. The unit I got is made by Peterson Manufactrining, modle 5000 solid state flasher. 0.01 to 17 amps. Never had a problem since. good luck

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