80 series high mounted stop light (remounting and troubleshooting)?

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landcruiser3DP

landcruiser3DP

Joined
Apr 9, 2017
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2,550
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tejas
can anyone help me figure out how to methodically troubleshoot a non-working upper rear hatch brake light? i got some awesome help troubleshooting two issues related to LEDs in my two dome lights (thanks!) so i want to see if i can build on this with the upper rear hatch brake light issue.
i've sanded down and cleaned up this center console ground point. i've also taken the light out and hooked it up to 12V source and the light does in fact work outside of the vehicle.
also does anyone know how to get this plastic housing back over the light once it's mounted?
for a first step i am going to clean up the ground that looks like it's under the vehicle and also i am going to see if i can find the two harnesses in the left rear pillar(?).
THANKS

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My Non methodical response:
Bad diode. Check out this thread and post #8.
jpoole

Thread 'Let's not get rear-ended (3rd brake light upgrade with pics)'

The stock, led third brake light on my '97 was puny. I had replaced the diode to get it going again but some of the bulbs were no longer working and the ones that did work were fairly dim. Rather than try to get more out of the old lights I replaced them with new bulbs which turned out to be cheap, easy and very effective.

To start I ordered 1 unit of these:

Outdoor Single-Color LED Strip Light - Super Flexible w/ Through Hole LEDs - 12V - Waterproof IP67 - 85 Lumens/ft​
SKU: WFLB-R96​
Color Options: Red​
Price: $22.95​
​
...
  • Like
 
There are a few common failure modes for these, search for 3rd brake light fixes on the forum and you'll find them. Example:

LandLocked93

Thread 'Third Brake Light troubleshooting/rebuild tips'

If your 3rd brake light is not working, working poorly, or half working. Only a few pics and assuming basic familiarity with soldering, soldering irons, and heat. And this is just the tools and methods I used to address the situation on my hands: light was working but it was very dim and half the LED's wouldn't light up.

Shoutout to the MUD member posting this link (can't find it again) DIY Landcruiser Third Brake Light Fix: $0.69 - http://the36thlock.blogspot.com/2010/08/diy-landcruiser-third-brake-light-fix.html. I went with their zener diode voltage - 5.1V They say if the...
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I fixed mine but it wasn't that bright so I replaced the stock led strip with a new one that is brighter and inexpensive enough to easily replace if/when needed. You can see my old post about this change here:

jpoole

Thread 'Let's not get rear-ended (3rd brake light upgrade with pics)'

The stock, led third brake light on my '97 was puny. I had replaced the diode to get it going again but some of the bulbs were no longer working and the ones that did work were fairly dim. Rather than try to get more out of the old lights I replaced them with new bulbs which turned out to be cheap, easy and very effective.

To start I ordered 1 unit of these:

Outdoor Single-Color LED Strip Light - Super Flexible w/ Through Hole LEDs - 12V - Waterproof IP67 - 85 Lumens/ft​
SKU: WFLB-R96​
Color Options: Red​
Price: $22.95​
​
...
  • Like
 
ERG80 said:
My Non methodical response:
Bad diode. Check out this thread and post #8.
jpoole

Thread 'Let's not get rear-ended (3rd brake light upgrade with pics)'

The stock, led third brake light on my '97 was puny. I had replaced the diode to get it going again but some of the bulbs were no longer working and the ones that did work were fairly dim. Rather than try to get more out of the old lights I replaced them with new bulbs which turned out to be cheap, easy and very effective.

To start I ordered 1 unit of these:

Outdoor Single-Color LED Strip Light - Super Flexible w/ Through Hole LEDs - 12V - Waterproof IP67 - 85 Lumens/ft​
SKU: WFLB-R96​
Color Options: Red​
Price: $22.95​
​
...
  • Like
Click to expand...
i was going to try to post a picture of this but i couldn't find it. if i tested the brake light itself by hooking it up directly to the battery and it lit up doesn't this mean it is not the light fixture itself?
 
Sorry, I didn't read your message very closely. I've seen folks report the failed diode scenario enough times to have made assumptions here. Clearly you've been around long enough that you've likely seen those threads also.

I think the black cover snaps on/off. The plastics are fragile and a bit of silicone lubrication could make sense on the snap connections. A visual inspection should make it obvious how the cover goes back on and I've not had mine off in a few years so may be mistaken so check before pushing too hard. You may find pictures of that cover in the thread I linked to above that help?

On my '97 I've had issues with wire failures inside the rubber tube that connects the body to the upper/rear hatch and there are only a few wires in there so you may want to consider this as a possible source to for the issue to check. In the case of my 80 the broken wires were easy to spot once I had unhooked the rubber tube from the body and slid it to one side. I had a wire broken completely and then cracked insulation on a few others.

I've also had weird taillight issues related to the ground points that are soldered to the bulb sockets in the two lower brake lights. Basically the ground wire is soldered to the side of the dual-filament light housing and it can come loose. I've seen this on the driver side of a few 80s and without that ground you can get partial brake lights and different behaviors with driving/parking lights on/off.

I like to start with the easiest options first but haven't needed to fix more than the above issues on my 80 related to the brake lights so don't know if you have easier points to test for voltage on that circuit along it's length, etc. but those are possible failure points to look into at least. Perhaps you could use a small stick to prop the brake pedal down and then clip a volt meter onto the + - source wires for the tail light and wiggle the wires from body to rear hatch to see if the connection is intermittent there with minimal effort? You can also test the + and - wires separately to determine if one or both are causing this issue which may help.

Good luck
 
jpoole said:
Sorry, I didn't read your message very closely. I've seen folks report the failed diode scenario enough times to have made assumptions here. Clearly you've been around long enough that you've likely seen those threads also.

I think the black cover snaps on/off. The plastics are fragile and a bit of silicone lubrication could make sense on the snap connections. A visual inspection should make it obvious how the cover goes back on and I've not had mine off in a few years so may be mistaken so check before pushing too hard. You may find pictures of that cover in the thread I linked to above that help?

On my '97 I've had issues with wire failures inside the rubber tube that connects the body to the upper/rear hatch and there are only a few wires in there so you may want to consider this as a possible source to for the issue to check. In the case of my 80 the broken wires were easy to spot once I had unhooked the rubber tube from the body and slid it to one side. I had a wire broken completely and then cracked insulation on a few others.

I've also had weird taillight issues related to the ground points that are soldered to the bulb sockets in the two lower brake lights. Basically the ground wire is soldered to the side of the dual-filament light housing and it can come loose. I've seen this on the driver side of a few 80s and without that ground you can get partial brake lights and different behaviors with driving/parking lights on/off.

I like to start with the easiest options first but haven't needed to fix more than the above issues on my 80 related to the brake lights so don't know if you have easier points to test for voltage on that circuit along it's length, etc. but those are possible failure points to look into at least. Perhaps you could use a small stick to prop the brake pedal down and then clip a volt meter onto the + - source wires for the tail light and wiggle the wires from body to rear hatch to see if the connection is intermittent there with minimal effort? You can also test the + and - wires separately to determine if one or both are causing this issue which may help.

Good luck
Click to expand...
thanks man. on inspecting wires the rubber tube is this thing here (green)? and i pull it out and slide the tube aside or something?
and i also open up this side pillar (orange) further to get at the connectors is that right?
also i also wasn't clear on the cover for the brake light. it came off easy enough with some gentle prying. but it went on very tight against the rear glass and i can't get the right angle to get these brass studs in (red).

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landcruiser3DP said:
i was going to try to post a picture of this but i couldn't find it. if i tested the brake light itself by hooking it up directly to the battery and it lit up doesn't this mean it is not the light fixture itself?
Click to expand...
Maybe. Did you test if the 3rd brake light wires are getting power when brakes are applied?

This shows reassembly and I think that panel is covered around 6:10.
 
landcruiser3DP said:
on inspecting wires the rubber tube is this thing here (green)? and i pull it out and slide the tube aside or something?
and i also open up this side pillar (orange) further to get at the connectors is that right?
Click to expand...
In my case I pulled one end of that rubber, flexible, black hose loose from the body panel it is slipped into and then "scrunched" it down until I could visually inspect the wires near the middle where they flex the most. You may have to pull both ends of the rubber tube out of their body panels and inspect from both directions. Be gentle, don't tear/damage the tube or stress the wires but there is enough wiggle room to inspect the wires where they flex and can work harden and break.

To implement repairs I needed to pull the headliner down near the rear left/driver side corner so that I could disconnect a few wire ends and then work them out where I could repair them by splicing in new wire and installing heat shrink, etc. I didn't want to do that work in a way that may melt or damage the rubber tube so I pulled the wires out and clear of the rubber conduit.

There are many variables here that may be different for you and you may have no wiring damage inside that flex tube at all, I just wanted to share an issue I've seen and that seems more likely than some other failure modes. This is also why I would put a meter on the power and ground wires for the brake light, press the peddle with a short pushrod and then wiggle the harness around to see if the connections are intermittent (they may or may not be depending on the break/issue) since if they are intermittent when you wiggle the flex tube you've likely found your issue and can deal with digging in for repairs. I'd also test both the power and ground independently just to get a better sense of where the problem may be.

At this point it seems like you don't have both positive and negative circuit continuity to the 3rd brake light (though you may have one of these) so you are going to be chasing one or both of those back until you find the issue. I've share the most common issues I'm aware of (bulb socket ground, broken wire at the flex point, diode failure on the 3rd brakelight bulb/board) but you've ruled out the failed diode so need to focus on the positive and ground circuits. I'm sure there are helpful references in the posts before my first one on this thread and if you search more you may get tips for accessing the involved wires along their route to the back hatch which is the real trick here, finding and testing those circuits. Ruling out the common items above may be easier than some of the tests / digging that further troubleshooting may require.

Good luck
 
Upon reassembly...

truthdetector

Thread 'Third Brake Light Inside Trim - Fix Rattle'

Removing the third brake light trim is bound to break whatever insert was present in the brake light assembly that the three posts in the trim seat into. Without those inserts, the trim is not secure and rattles around a lot.

I happened to have a misc. grommet kit and the smallest grommet from the kit (M7.14) fits perfectly in the holes in the brake light.

Cut a slit in the grommet and put a drop of lube on it so the posts don't push the grommet into the brake light.

Now, the trim is holding perfectly.

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truthdetector said:
Upon reassembly...

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i can't get the damn thing in. i need for sake w video. somehow the angle won't let me get the brass pins "horizontal" enough to slot them in the holes. the cover hits the glass first.
last night i tried to force it at an angle and busted two grommets so this will come in handy (thanks).
i'll have to do a video. aside from having the light standing up too high on the mettle bracket so the holes are too close to the glass i don't know wtf i am doing wrong honestly.
her are pics from the video kindly posted above. at one point i thought i was trying to mount the cover oriented wrong but not sure that is the case...

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