Brake lights and cruise control (1 Viewer)

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There's some correlation between them.

Before I dug into replacing my radiator and power steering pump and hoses, I had an issue where my cruise control would work fine but as soon as I turned on my lights, cruise control is disabled.

With lights off again they work. Using a turn signal to switch lanes it still works.

Turning lights back on and checking the exterior lights, my driver rear turns off if I hit the brakes (LED light it turns off, switching to halogen and pressing the brakes it dims instead of getting brighter).

However my passenger rear brake light/lights are on as if I'm touching the brakes, but without touching the brakes.

I checked the grounds that I could get to in my engine bay and they're on nice and tight, no weak ground as I made sure they were making contact.

Anyone give me a lead on a certain ground wire I may have missed or a general location that'll affect both rear lights and my cruise control?
 
As I'm sure you know, the brake pedal closes a switch that:
1) turns on the rear brake light, always
2) unlocks the gear shift lever when in park with key on
3) cancels the cruise control

I think you have a floating ground where the current from your taillights is finding an alternate path to ground by energizing your brake light circuit.

I addressed a floating ground on my rig this year and was experiencing similar issues. My floating ground was where the ground wire attaches to the body of the brake light socket
 
This happened to my 97 model a few years ago, exact same symptoms started immediately after replacing a burned out tail lamp bulb. That bulb was likely the original as it had the typical silver appearance from the vaporized filament coating the inside of the bulb. The replacement was a standard filament type Sylvania bulb.

Pulled the new bulb out (that caused the issue) and the cruise control came back with the headlamps on. Later I installed the other new bulb from the same package, same thing, cruise control would shut off when the headlamps were turned on, so removed that one also.

So assuming I got a set of bad bulbs I bought a second set of bulbs, same type, Sylvania (only brand I could find while traveling), and installed one of those, and no problems. Been running that bulb for a few years now.

Never figured out exactly what the cause was but assumed it was due to a bad set of bulbs??
 
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As I'm sure you know, the brake pedal closes a switch that:
1) turns on the rear brake light, always
2) unlocks the gear shift lever when in park with key on
3) cancels the cruise control

I think you have a floating ground where the current from your taillights is finding an alternate path to ground by energizing your brake light circuit.

I addressed a floating ground on my rig this year and was experiencing similar issues. My floating ground was where the ground wire attaches to the body of the brake light socket

Actually I didn't; wasn't sure if it was the same as say...a 1st Gen Taco/3rd Gen 4R (previously owned them) but good to hear it's the same.

I mentioned grounds based on my assumption; you only confirmed it.

With that said, I'll look around the rear by the brake light sockets in hopes to find the issue so that helps give me a place to start. I had thought about looking in there but didn't on account of the rat's nest of wires in there.
 
This happened to my 97 model a few years ago, exact same symptoms started immediately after replacing a burned out tail lamp bulb. That bulb was likely the original as it had the typical silver appearance from the vaporized filament coating the inside of the bulb. The replacement was a standard filament type Sylvania bulb.

Pulled the new bulb out (that caused the issue) and the cruise control came back with the headlamps on. Later I installed the other new bulb from the same package, same thing, cruise control would shut off when the headlamps were turned on, so removed that one also.

So assuming I got a set of bad bulbs I bought a second set of bulbs, same type, Sylvania (only brand I could find while traveling), and installed one of those, and no problems. Been running that bulb for a few years now.

Never figured out exactly what the cause was but assumed it was due to a bad set of bulbs??

I have a '95 and am experiencing the exact same symptoms, also after replacing a burned out driver side tail lamp bulb from the dealer. Also, when I press the brakes, the radio and clock lights dim. I'll try what you did and report back.
 
There's some correlation between them.

Before I dug into replacing my radiator and power steering pump and hoses, I had an issue where my cruise control would work fine but as soon as I turned on my lights, cruise control is disabled.

With lights off again they work. Using a turn signal to switch lanes it still works.

Turning lights back on and checking the exterior lights, my driver rear turns off if I hit the brakes (LED light it turns off, switching to halogen and pressing the brakes it dims instead of getting brighter).

However my passenger rear brake light/lights are on as if I'm touching the brakes, but without touching the brakes.

I checked the grounds that I could get to in my engine bay and they're on nice and tight, no weak ground as I made sure they were making contact.

Anyone give me a lead on a certain ground wire I may have missed or a general location that'll affect both rear lights and my cruise control?
The complete EWD is in the Resources section. Here's the ground points section.
 

Attachments

  • connectors (ppg 30-39).pdf
    470.2 KB · Views: 70
I have a '95 and am experiencing the exact same symptoms, also after replacing a burned out driver side tail lamp bulb from the dealer. Also, when I press the brakes, the radio and clock lights dim. I'll try what you did and report back.

With the wife close to delivering, being in school, and doing sidework, I haven't fixed it yet!

And unfortunately my rear windshield wiper motor quit not to mention the rear defrost isn't working.

The complete EWD is in the Resources section. Here's the ground points section.

You are a godsend!
 
With the wife close to delivering, being in school, and doing sidework, I haven't fixed it yet!

And unfortunately my rear windshield wiper motor quit not to mention the rear defrost isn't working.



You are a godsend!


Here's a complete '96 wiring diagram, should work for us
 

Attachments

  • 1996+Toyota+Land+Cruiser+EWD.pdf
    3.9 MB · Views: 35
IIRC those components all share the same ground... could be a good place to start when your tracing the circuit back.
 
I checked the grounds that I could get to in my engine bay and they're on nice and tight, no weak ground as I made sure they were making contact.
^^^^

FWIW.... a ground that is 'nice and tight' doesn't mean it is good.

Anytime I encounter a suspected ground issue, I will remove the ground point, inspect the terminal end and surface area it connects to. Clean both really well. Reconnect. Use a test light to then confirm the ground is complete. Bulb 'sockets' are the worst to diagnose it seems.

Yeah, its a pain in the butt....but so are ground issues. Anytime you have really wonky symptoms with dash lights, controls or other electrical components (especially multiple issues) it is generally a bad ground.
 
there are also like two or three connectors in the rear hatch behind the trim panel that are notorious for developing bad connections due to corrosion. It's a 5-minute job to pull the panel off, take the connectors apart clean them and put it all back together. That solved my wiper & defroster issue.
 
Also, I think you'd stand a high chance of solving the issue by simply adding inline resistors to the turn signals. Since they are momentarily on the resistors won't generate much heat at all. Might be the simplest imperfect solution if it works.
 
Man, if the street sweeper would just stop circling around (he's gone by 9 times, never done this before).

Pulled the inside hatch panel, disconnected all plugs, cleaned them, and the wiper motor issue is still present.

I've always heard a "click" like a relay when I'd turn on the rear wiper motor (still do) but no movement so that's still down.

With that said, I went back to the bulb sockets and decided to clean them all up.

Further inspection reveals a loose white wire with black stripe; previous experience me tells this is a ground cable. This loose wire is on my driver side.

Pulling the cable out, does not remedy nor worsen my light issue nor does it change it.

Putting the cable in contact with the bulb socket does not remedy nor worsen my light issue nor does it change it.

So I'm still wondering if this wire is the root of my problem? Keep in mind, the driver side is the one where the bulb turns off if I hit the brakes with the running lights on, but acts normal with the running lights off.

20230316_152915.jpg


The passenger side is the side that is extra bright with the running lights on, but works like normal with the running lights off when I use my brakes.

20230316_152927.jpg


I ask because maybe that wire wire with black stripe is in contact with another part of the bulb socket and not the metal socket itself?
 
Man, if the street sweeper would just stop circling around (he's gone by 9 times, never done this before).

Pulled the inside hatch panel, disconnected all plugs, cleaned them, and the wiper motor issue is still present.

I've always heard a "click" like a relay when I'd turn on the rear wiper motor (still do) but no movement so that's still down.

With that said, I went back to the bulb sockets and decided to clean them all up.

Further inspection reveals a loose white wire with black stripe; previous experience me tells this is a ground cable. This loose wire is on my driver side.

Pulling the cable out, does not remedy nor worsen my light issue nor does it change it.

Putting the cable in contact with the bulb socket does not remedy nor worsen my light issue nor does it change it.

So I'm still wondering if this wire is the root of my problem? Keep in mind, the driver side is the one where the bulb turns off if I hit the brakes with the running lights on, but acts normal with the running lights off.

View attachment 3274190

The passenger side is the side that is extra bright with the running lights on, but works like normal with the running lights off when I use my brakes.

View attachment 3274192

I ask because maybe that wire wire with black stripe is in contact with another part of the bulb socket and not the metal socket itself?

Disregard gents, it was pinched/cut at the taped end on top. Fixed!
 
The loose wire should be connected to the side of the bulb socket, which is the ground part of of the socket/plug. I've fixed this on a few 80s by soldering them back on with a decently hot iron, after cleaning wire/housing a bit.

On my 80 the rear wiper started acting up after the wires that flex when the upper rear hatch opens shorted out. Since all of our 80s are getting old this is worth keeping open as an easy to fix option. The break/short was inside the rubber boot/tube between body and upper hatch. I was able to pull enough slack to fix them pretty much in place, including with the rubber boot that covers them from body to upper rear hatch. I re-spliced them using solder and adhesive lined heat shrink to keep their size down so that they fit back into the rubber boot/tube cleanly and have had no issues since. I had to partially pull the headliner down in the drivers rear corner so that I could unplug the wires that pass to the rear hatch to get some working slack.
 
Be sure to test your brake lights and blinkers with your running lights on and off. You should have problems if that ground in pic 1 above is not connected.
 
why don't you get your factory service manual through the page linked in my description, which has all the electrical wiring diagrams in it for free? That way you don't have to guess what s*** is? I feel like a broken record repeating this all the time...

1520202524968.jpeg
 
why don't you get your factory service manual through the page linked in my description, which has all the electrical wiring diagrams in it for free? That way you don't have to guess what s*** is? I feel like a broken record repeating this all the time...

View attachment 3274292

There was no guessing; the diagram (I downloaded them) told me where the wiring was and I chose to follow the wiring with said diagram only to find no issues in the few areas I checked.

Also found that the unplugged harness on the passenger side was for an OEM subwoofer I don't have anymore.

So yes, the link was helpful...not sure why you're upset if the issue was rectified?
 
Well, I assumed you hadn't done so because of this statement which sounded like you were assuming when you wouldn't have had to if you were consulting the EWD. My bad

Further inspection reveals a loose white wire with black stripe; previous experience me tells this is a ground cable. This loose wire is on my driver side.
 
Well, I assumed you hadn't done so because of this statement which sounded like you were assuming when you wouldn't have had to if you were consulting the EWD. My bad

Confirmed in the diagram when I went to my laptop; had it open with music playing (usually use it for my CNC or just bluetooth music via laptop).

Was posting from my phone when I posted the above.

It happens, no worries. Thanks for the links though.

The real irritating part was the street sweeper came through 11 different times in our neighborhood; come to find out the old guy driving was taking turns with the younger guy inside teaching him how to run it along the sidewalks and whatnot.

Thing is everything he'd come near, I'd shut the hatch and go to the garage and wait for the dust to settle cause it'd kick up dirt and dust everywhere each and every time.
 

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