Troubleshooting a turn signal switch in an FJ40? (1 Viewer)

[Clubtroy]

The license plate lights do not contribute to the resistance of the turn signal circuit since they are not part of the turn signal circuit.

Check the connector to the switch first. It is a good place to verify that there is voltage getting to the circuit. On the switch side of the connector you can verify that the switch is working or not with the resistance function of your multimeter. Once you have that information you can decide if you need a new switch.

Hi Cromagnon - I am reading 1.7V at the turn signal switch after cleaning. What would the resistance need to be and should I measure at the soldered terminals on the back of the circuit board?

 

[Cromagnon]

Hi Cromagnon - I am reading 1.7V at the turn signal switch after cleaning. What would the resistance need to be and should I measure at the soldered terminals on the back of the circuit board?

You state that you are reading 1.7V at the turn signal switch. What is the battery voltage?

You should do a continuity measurement at the connector that comes from the turn signal switch. What resistance do you get between GL and GB, GL and GY with the switch in the off position, switch in the left turn position and switch in the right turn position. Also measure GL to ground, GB to ground and GY to ground. The lower the resistance the better, preferably 0 ohms, except for the measurements to ground which should be infinite.

 

[Clubtroy]

You state that you are reading 1.7V at the turn signal switch. What is the battery voltage?

You should do a continuity measurement at the connector that comes from the turn signal switch. What resistance do you get between GL and GB, GL and GY with the switch in the off position, switch in the left turn position and switch in the right turn position. Also measure GL to ground, GB to ground and GY to ground. The lower the resistance the better, preferably 0 ohms, except for the measurements to ground which should be infinite.

The battery is new and full 12V. That is my concern at the switch terminals. I'm not in front of it right now but I was checking the voltage at the terminals on the soldered joints on the printed CB in the switch and thought that was very low and likely the issue. The flashers all work great and I ran a new ground to one of the front signals to eliminate that culprit. I will be checking the resistance when I pull it back home from my deer lease in a couple weeks. Thanks for the advice.

 

[franklin40]

reviving an old thread here. my rear signal lights don’t work. it’s a 1972 fj40. my fronts do, my flashers work and my rear running lights do and my brakes do. just no signal lights to the rear. i’ve checked wires and grounds (i assume being the brake and flashers work the grounds are good anyway). i’ve pulled the harness connector and in the front right firewall area and cleaned the harness there. it was pretty cruddy but nothing changed. is there another area i should be looking? i assume my signal switch is fine as the fronts work, flasher is obviously fine. it’s got to be in the rear wiring connections but i can’t find any other connectors that might be the culprit. also around the same time this happened my interior done light stopped working. coincidence or related i dont know. if anyone has a little guidance as to where to check next that’d be helpful

 

[pb4ugo]

If your rear brake lights work and the flashers work in the rear(same bulb filament), then your problem is most likely in the switch. The switch disables the brake light when you activate the turn lever and turns on the directional signal. The switch is very basic and simple to work on.

 

[franklin40]

ok that actually makes sense if that’s how it works. k ill pull the wheel and see what i can find.

 

[pb4ugo]

I maybe Wrong, I was thinking about an fj55 column switch. It probably works in a similar way though. It has to stop power from the brake light for the turn to work.

 

[franklin40]

i’ll start there anyway. it been happening since i did my power steering mod which required the column to come out and in a bunch of times. could very likely be in that area.

 

[zerotreedelta]

I'm a little tired, but I think the blinkers are fully separate from the brakes on the 40 due to the two bulb/two color setup, unlike modern cars .. unless the 72 is different from the 76.

If both don't work in the rear, I'd verify they don't fire at that firewall connector then dig my way back up to the switch. I recall that the flasher is actually before the switch on my 76, but again, not sure on the 72.

 

[pb4ugo]

They're different, 72 has a combination stop/turn along with a taillight.

 

[zerotreedelta]

Sneaky!

 

[RodrigzCrzr]

Check your fuse in the meter part of the block.
The contacts may be dirty.
I had the same problem with my 71.
I was getting an intermittent contact being the blades where dirty on the fuse block.