UPDATED: Tail light help

[smwmustang]

So could the headlight combo switch be bad?

Foglights not working either but turn signals do

 

[Dirt J]

Possibly. Pull the relay and fuse and plug that connector in. Then see if you have 12v at any of the RELAY terminals. You shouldn't...

 

[smwmustang]

Possibly. Pull the relay and fuse and plug that connector in. Then see if you have 12v at any of the RELAY terminals. You shouldn't...

Hard to test back where relay is but the fuse has 12v all the time. Ill test one more time without the relay

 

[Dirt J]

Yes the fuse should have 12v at all times on one side, even with key off .

 

[Dirt J]

You can make a short jumper wire to plug into the relay terminals then test the closer end of the jumper wire.

 

[smwmustang]

You can make a short jumper wire to plug into the relay terminals then test the closer end of the jumper wire.

I can barely get my hand back there to mess with the relay. Of the 4 plugs on the relay, which one is the area to test

 

[Dirt J]

Find the green wire with black stripe in that connector you have unplugged and see if it has 12v

 

[Dirt J]

Terminals 2 and 5 should have 12v all the time when the fuse is in.

Terminal 3 is the output to the taillight circuit.

Terminal 1 should ground when the taillights are set to on via the combo switch.

 

[Dirt J]

You can rule in/out the combo switch by manually jumping terminal 3 to terminal 5. With the fuse in (and the relay out of course) this will switch on the taillight circuit manually. If nothing blows and the lights all light up, then its something upstream toward the combo switch.

 

[smwmustang]

You can rule in/out the combo switch by manually jumping terminal 3 to terminal 5. With the fuse in (and the relay out of course) this will switch on the taillight circuit manually. If nothing blows and the lights all light up, then its something upstream toward the combo switch.

Got it. Toyota must have believed a relay would never need anything to put them on the back of that panel.

 

[smwmustang]

Find the green wire with black stripe in that connector you have unplugged and see if it has 12v

Ran a quick test this morning with battery connected, fuse out and relay in. Green wire with black stripe had no power. Actually no wire in that bundle had 12v.

 

[smwmustang]

Just for kicks I had another headlight switch and swapped them out. Fuse blew immediately. Going to try the jumper wire to relay, just didn't have time tonight.

 

[smwmustang]

Ok further testing and research says this bundle is directly related to illumination. Testing continuity from the tail fuse the large red wire and green/orange wire have continuity on the block side. On the wiring connector side the whit/black wire and red wire have continuity which if I understand correctly means the red wire is a dead short....I think. Still need some help where to look. Does that red wire run to the back. Trying to find the wiring diagram of that bundle but I must not be looking in the right place

 

[Dirt J]

White with black stripe is ground. Where are you seeing those other wires? Also are you sure its green with orange stripe, or is it possibly a white stripe?

 

[smwmustang]

White with black stripe is ground. Where are you seeing those other wires? Also are you sure its green with orange stripe, or is it possibly a white stripe?

They are in the harness I posted a pic of. It is green wire with orange stripe and blue dots.

 

[Dirt J]

Green with orange stripe in that connector is stop light circuit. Sends 12v to stop light switch then to the rear brake bulbs.

 

[smwmustang]

Green with orange stripe in that connector is stop light circuit. Sends 12v to stop light switch then to the rear brake bulbs.

View attachment 4160828

So if i am reading this right, I'm new at this part, the green/orange come from the fuse block and then goes to switch where it becomes the green and white wires to the rear lights. Trying to trace it back from where it plugs in. I have ordered the full wiring book for the 99 LX.

 

[smwmustang]

So if i am reading this right, I'm new at this part, the green/orange come from the fuse block and then goes to switch where it becomes the green and white wires to the rear lights. Trying to trace it back from where it plugs in. I have ordered the full wiring book for the 99 LX.

Also, the brake lights work, its the running lights that are not working. But that wire is connected to the tail fuse, it has continuity anyway

 

[Dirt J]

So if i am reading this right, I'm new at this part, the green/orange come from the fuse block and then goes to switch where it becomes the green and white wires to the rear lights. Trying to trace it back from where it plugs in. I have ordered the full wiring book for the 99 LX.

No, the G-O wire goes to the brake switch. Then a G-W wire leaves that switch are runs rearward to the brake lights.

 

[smwmustang]

No, the G-O wire goes to the brake switch. Then a G-W wire leaves that switch are runs rearward to the brake lights.

Yes, sorry thats what I meant I think. That green/orange wire leaves the fuse block where its plugged in and then to the switch where it becomes green/white.