Brake lights not working

Yep, the ground should be OK since both blinkers are working. It's both the rear lights, i don't think the third upper light ever worked, I never wound up trying to replace those bulbs since i was ok with the two main ones working.

I'll try to do some more trouble shooting when i get home based on your direction. When i bought the vehicle a couple years ago the previous owner had a different steering wheel on it and when he wired it back up the horn doesn't work and the airbag light is always on. So i knew when i bought it those weren't working but the brake light problem is new. Probably wise to just bring it in, have some shop fix the horn, airbag and lights all in one swoop.

 

Are you sure both sides of fuse don't have power? You are 1997 model right? Then this is the fuse in the engine compartment box. It would be very strange if the fuse is not powered up, as the power to the fuse comes from quite hefty circuit powering a bunch of vital to the truck. . It can be as simple as this 15A fuse being blown.



Just so you know, post 2000 trucks have a little different diagram and location of the stop light fuse. Later models have 50A J/B for medium current fuse located in the engine compartment that powers fuses in the kick panel fuse box (one of them is 10A stop light). Before that year (including 1997) stop light fuses and some other were in the engine compartment powered directly from 80A Alternator fuse.

 

Man, you are blowing my mind with all this useful info. My panel look different than that one above. This is the layout here. You are correct it's a 1997, 2.4L, 2WD.
The site below is what drew my towards fuse 1 being the culprit.
http://wikicars.how/fuse-box-diagra...1997-fuse-box-diagrams-location-and-amperage/


I replaced fuse 1 which is the brake one. I swear I touched both terminals with my multimeter and got 0, maybe i'll try again tonight.

 

Yeah man RysiuM really does know this stuff and he can explain it in a way to really help peeps understand too. Very detailed and proficient, he is. I'm pulling for you man. It's gonna be something relatively simple, that's why I don't want you to take it in to get fixed. You know how to test for continuity and DC voltage, you'll be able to do this.

 

You are correct - Fuse number 1 on your picture. I just looked at my 95 box and it looks like yours. The picture I put originally was from 99, I did not know that they changed the box design leaving most of connections the same.

Here is the box diagram for 95 (very probably is the same or very close to 97). That picture actually shows the connection between fuses and relays - helps with investigation.




Eh, Toyota.

And I agree, unless your wiring were messed up by some so called "electro-mechanic" or were chewed up by rodents, it can't be hard to find the issue. Besides faulty fuses and switches look for overheated and/or corroded connectors.

 

So I got back from work and tested the fuse again,good to go, so that's no issue. (yesterday i was trying to take the voltage incorrectly).


I also found this in the Haynes Manual. I just removed the stop light switch connector and tested both of those just to see if there was any voltage present, just read 0. So somewhere between the fuse box outlet to the connector of the stop light switch has a short in it somewhere. Am i drawing the right conclusion? To me this sounds like a weird part of the distribution that would fowl up.

Here's a better hires pic of the diagram https://imgur.com/gD2HGP9

 

So no voltage at the connector that goes into the brake light switch? What's in front of the brake switch, electrically speaking?

 

Have you tested the continuity of that fuse? You have that same voltage on both sides of the fuse right?

 

Yeah, i did the test on both sides of the fuse and I'm good. I just made a couple videos that might help shed light on the situation.
around break area
https://youtu.be/1CbjlMDRXMI
Fuse area
https://youtu.be/3_Y4RpiX5Is

Here's where i took my ground from.

 

Also, highlighted the diagram from the Haynes manual this morning. See attached and below

 

Just went through a very similar situation. No brake lights, no blown lamps or fuses. Strange glowing left arrow on dash when running lights on.. This time like last time --- I DISCONNECTED THE TRAILER WIRE HARNESS FROM BOTH SIDES. ALL BACK TO NORMAL. This is the exact second time it has happened. This time with the new harness installed about a year ago. (I don't even think I ever got a chance to use it since I installed it) These friggin things are junk. I seem to recall a post about a guy opening the box and fixing a failed component on the board. Seems like many of these fail. I wish I could find a good one that would last

 

Sorry for long post.

You will wind both diagrams identical, just Toyota give you pin numbers. So assuming your wiring were not modified (or messed up) the diagnostic procedure I would do.

First of all, if you have trailer adaper take it out. It's common thing for them to act badly messing up the electrical in our trucks. The problem is that they are cheaply designed and feed the power to trailer directly from the tail lamps. Modern adapters (in Europe I see only "modern" types) power trailer lights from separate power cable going streigh to battery (via fuse) and each circuit is turned on and off via micro or electronic relays. Tail lights signal is used only to control these relays, and they never draw more than few mili-Amps.

1. Remove the Stop light fuse from the socket. Using cheap HF multimeter check continuity on fuse. Should show continuity. If not, replace the fuse.
2. Verify the voltage between battery negative and each contacts of the fuse holder. One should read 12V (or whatever battery voltage is) and the other should read zero. If there is no voltage on any contact of that holder there is a problem with the fuse box (assume that 80A Alternator fuse is not blown).
3. Verify continuity between battery negative and the fuse holder contact that showed zero. Should be open. Press brake pedal and verify that continuity again. Should be closed. If not, there is a problem downstream of Stop light fuse. If the continuity shows when brake pedal is pressed than there is a problem downstream of brake pedal.

Checking downstream of Stop light fuse.
1. Unplug the connector from Stop light switch. For testing that connector you will need much thinner probes than you would normally have on multimeter. Use something like cloth pin or thin piece of wire.
2. Test the Stop switch. There should be no continuity between switch contacts when pedal is not pressed and the continuity should appear when the brake pedal is pressed. If not, the brake switch is possible faulty
3. test the continuity between the contact of the Brake switch plug that is on the Green-Yellow wire and the contact of the stop light fuse - the contact that did not have 12V measured in step 2 before. If there is no continuity there is a problem in wiring between fuse box and the plug. Most likely in the fuse box (unless rodents got into the truck).
4. If there is continuity put back the Stop light fuse and verity that wire you measure 12V between the contact of the Brake switch plug that is on the Green-Yellow and battery negative. If it is not, than the fuse holder has bent or rusty contacts (very unlikely).
5. Check the continuity between contact of the Brake switch plug that is on the Green-White wire and the battery negative. If the circuit between fuse and the switch is OK, you should have the same result as in 3 when the brake pedal is pressed.

Checking downstream of Stop light switch.
It is extremely difficult to get to J/B No3 without disassembling the whole dash. That sucker is hidden behind the instrument panel and you can see it if you lay on the floor but good luck even touching it. The good thing is that it probably never fails unless you submerge the truck in the ocean for some time. So for that I would skip checking connections to and from J/B No 3 and just check the connection between the stop light sockets and the stop light switch.

You need long wires so you can check continuity between the cabin an the tail of the truck. Also if you don't have camper you may be able to check the top mounted stop light as well.
1. Unplug the tail lamp and check the continuity between the contact of the Brake switch plug that is on the Green-White wire and the contact number 4 (see the image below) of the tail light plug. Number 4 will be the one that has Green-White wire. Do that on the both sides. You should have continuity. If not, then it is a long investigation where that wire is broken - from the switch it goes to J/B No3 and then in the loom on the floor on the left side near the door, goes through the hole under the driver seat and along the frame goes to the rear of the vehicle.

2. If continuity is there reconnect the stop light switch and check the voltage between the contact number 4 of the tail light plug and the battery negative. When brake is not pressed, should be zero, when brake is pressed should show 12V. I would not expect anything different at this point.
3. The last check would require a spare stop light or turn signal bulb. Connect the "foot" of the bulb to contact number 4 and the metal case of the bulb with battery negative. When brake pedal is pressed the bulb should turn on. Be careful do not make a short.
4. If this is good, do the same test but connect the bulb between the contact 4 and 3. If this fails, there is a grounding problem. If it passes the issue is inside the tail lamp.

Tail lamp issue:
If all that checks put to this point the problem is most likely in the lamp itself. Verify continuity between pin number 3 and 4 on the lamp itself. Pin number 3 is the one that on the wire plug (on the truck, not the lamp) has White-Black wire. If there is a continuity time to check if lamp lights up when you put 12V between contacts 4 and 3. If is possible that contact show continuity for multimeter but have enough resistance to not power the bulb. If it fails most likely the issue us with the socket - they often go rusty with bad contacts. Clean them, fix them or replace the lamp.

Ground issue:
That is also interesting. Tail lamps are grounded inside the cabin (I think it shows on your video). The long wire goes along the frame inside the wire loom from the tail lamp all the way back into the cabin under the left kick panel. I would not suspect that that wire is broken but who knows.

Good luck.

 

just printed this gospel out and going to give it a go tonight! You are awesome! thank you very much

 

So i got through everything tonight, I checked continuity of the fuse. When continuity showed it read 0.00v compared to .OL.
Verified step 2: one did read 12v and the other 0. if you were looking at the vehicle the 12v side was to the left, the right terinal read 0.
Verified step 3: read 0.00V instead of .OL

Downstream of stop fuse light.
Verified the brake light switch works:I tested both the new and old brake light switch and it read 0.000V when depressed and .OL when pressed. So both of the switches are good. I'll just take the new one back when i fix this issue.

3. We tested continuity from the 0V side of the fuse to the green yellow wire and of the brake light switch plug and it read ".OL", no continuity. Also tested from the negative terminal of the battery to the green yellow wire of the brake light switch and it still read .OL (knew it would but wanted to check). I then touched the green white from the brake light switch to the negative battery and it read 0.000V for continuity. Which means it is upstream of the brake line switch and the green white off of the brake light switch. Which then further leads me to believe it is the wire leaving the fuse box to the brake light switch plug as you had indicated.

Pretty sure not mice or anything has snuck into my truck. Possibly in the engine well, very possible. If it is the fuse box i might want to trust someone better than me to replace that.

I'm really digging this, figuring out the s*** before i bring it to a shop and know how to do it the next time it may come around.

 

Great job on tracing that up. Before you open the relay box there is a last (faint) chance to get it before that. That is connector between looms (on the diagram below)




It is located on the left side under kick panel.



On this picture it looks like it is under the good, but it is behind the firewall (inside the cabin) somewhere close to groumet. That is big ass plug/socket with whole bunch of wires in it. You are still looking for Green-Yelow wire in the contact number 20.



One side goes to the switch, the other to the fuse box.

If the tests shows continuity on the plug-brake switch side and no continuity on the other plug-fuse box side you can narrow your research to the fuse box. Otherwise it is inside the cabin. In the cabin side there is additional connection if you have Cruise Control (and that shows differently between years, so it is hard to tell you exactly).

But at this point I think you are right - the best guess would be fuse box unless you see something obvious with the loom.

In any way if you decide to go to stealer for fix instead doing it yourself your diagnosis can lower the bill by giving them exactly what to fix instead of being bullshit by them that you need the whole new truck.

 

Awesome work testing man and knowledge is power! Even if you have someone else do the fix, at least you diagnosed it and they can't pull a quick one on ya. If you take it in, don't tell them you already diagnosed it. Let them tell you what problem is, even though you're almost there, that way you know if they're an honest outfit or not

 

What amazing help you provide on these electrical gremlins people face. I love reading your posts cause it feels like I always pick up something new I didn't know or realize before. I appreciate how detailed they are, so thanks a bunch. I'm sure I'm not alone and the community feels same way. You're a stud man

 

Thanks for kind words. The only problem I have is that Toyota is changing the electrical not only between versions and equipment but almost every year is different. Not just pin numbers on connectors but routing wires differently. For example the Cruise Control Stop Power connector (J8) is on all engine versions in 95 model (if truck is equipped with CC), while in 99 model that is only with V6 engine and in 2003 it disappeared altogether. I have complete diagrams for 95 and 2003 but only most of EWD for 99 and 2000 models. So for example dealing with 97 is based on some assumptions and similarities to near models, but still may not be 100% accurate, for which I apologize.

But still I love to learn about systems in cars so sometimes I just analyze EWD of different cars just for fun. Especially when dealing with the newest very computerized cars like my 2012 4Runner and 2014 Nissan. Challenging and fun.

 

I found it! It was from the fuse box up to the firewall. Some hooligan spliced wires. I did my best reconnecting them and the brake lights work! Though there is still a crappy jumper. The new one I had to run was the blue cable.


This leads me to a next question. What are the other jumper wires?
There's a white with a red stripe one.
A pure yellow one
A green with a red stripe.


Here's a video of the problem area https://youtu.be/RvVembnHAzg