2006 Rear Brake Light out - diagnose and repair (1 Viewer)

[tjb]

My 2006 driver’s side rear brake light is out.

It appears that *if* the light is not working that the entire assembly must be replaced (Part No. 81561-60700):

Or the switch assembly.

The lens assembly is a few hundred bucks. The FSM says to check the “bulb” (which is not accessible) or the bulb and the harness, but the Zen Koan of whether I have “Only one light always come on” or “Only one light does not come on” is beyond my comprehension. From the LIGHTING SYSTEM: PROBLEM SYMPTOMS TABLE for my LX:

The FSM includes this:

1. Is there a way to test the harness?
2. Where is that stop light switch assembly? (Neither end of my harness or the harness that it connects to just inside the fender resembles that diagram.)



Anyone with experience they can share here?

 

[IndroCruise]

Merriam Webster: Koan -- a paradox to be meditated upon that is used to train Zen Buddhist monks to abandon ultimate dependence on reason and to force them into gaining sudden intuitive enlightenment

Sounds like a very fair description when it comes to interpreting the wisdom of some parts of The Great Book a.k.a. the Factory Service Manual (FSM)!!!

A similar problem followed my discovery that the tail-light on my 2006 LC100 did not appreciate being backed into a fencepost, the “bulb” (being an LED array on that model) then stopped working! The 2006 LX470 is electrically similar below the skin ….

The FSM in its various versions will have had a large cast of different authors – some writing in Japanese and translated later by others, others writing directly in English as a Second Language. My own life experiences included many work relationships with Japanese business and technical persons over many years. In the case of Japanese Toyota/Lexus persons, the professional competency and technical proficiency will be very high. However, sometimes English language proficiency may be variable. It also can happen that the wording chosen and written in English is too literal, more so than a native English-speaking reader might expect.

These are my suggested "translations" of two cases:

Case 1: “Only one light [always] come on” -- “always” means always – and means power always is running in the circuit, for example if Ignition Switch is ON, regardless of whether the brake pedal is pushed. This requires a fault condition. The FSM suggests harness fault (also includes connectors), cannot be the stop light switch, cannot be the relevant ECU because either of these would affect both side brake lights and the high stop light – see circuit diagram at the link below. (By the way, the stop light circuit also links to both the ABS ECU and the AHC ECU. If either of these are receiving a “Brakes are ON” signal from these kinds of faults, then ABS and AHC problem symptoms and warning lights also may appear).

Case 2: “Only one light does not come on” – means what it says – whatever the driver does, including pushing the brake pedal, only one light does not come on.

You will know whether you have Case 1 or Case 2? It seems more likely to be Case 2.

If Case 2, the problem is either

• a harness issue, broken wire somewhere, or simply a loose or damaged connector (sometimes happens when the jack and tool roll are taken out of the LH rear fender, or when wiring is rearranged or disturbed when a rear bar is fitted, or when other changes are made,

OR,

• for a model later than May 2005 the “globe” has failed (which for this model actually is the LED array, not a single globe) – and expensive replacement of Lexus 81561-60700 is required unless a spare can be found from a vehicle being parted out.

Suggested first steps:

• Remove light assembly
• ,
• Test brake light by applying battery voltage,
• Request assistant to apply footbrake, check voltage being received from vehicle harness at the connector which is revealed when the light assembly is removed.

References:

Circuit for LC100 after May 2005 (LX470 is similar)
https://lc100e.github.io/pdf/ewd/em0020e/htmlweb/ewd/contents/system/main/OVER097.html

Routing:
https://lc100e.github.io/pdf/ewd/em0020e/htmlweb/ewd/contents/routing/main/WR012.html

 

[tjb]

I’m simultaneously grateful for the wiring schematics and reminded of why I never purchased them.

Can you help with some idea how to do these:

1. Test brake light by applying battery voltage,
2. Request assistant to apply footbrake, check voltage being received from vehicle harness at the connector which is revealed when the light assembly is removed.

In both cases, there are > 2 spots for leads … can I safely just try to find the right ones randomly?

 

[IndroCruise]

I’m simultaneously grateful for the wiring schematics and reminded of why I never purchased them.

Can you help with some idea how to do these:


In both cases, there are > 2 spots for leads … can I safely just try to find the right ones randomly?

Revised suggestion:

1. With LH stop-light assembly removed and disconnected, probe harness connector (not stop-light connector) with multimeter to ascertain which of the coloured wires carry voltage when brake pedal is pressed by assistant with Ignition ON (not necessary to start engine),
2. If wiring is the same as the electrical wiring diagram reference provided in previous post, expect to see battery voltage at harness between GREEN-WHITE (+) wire and WHITE-BLACK wire,
3. If LH harness voltage is confirmed, test LH stop-light by applying battery voltage across GREEN-WHITE (+) wire and WHITE-BLACK wire positions at the LH stop-light connector,
4. If no voltage is found at LH harness, for comparison repeat the procedure at RH side,
5. If the conclusion is no voltage at LH harness connector, scrutinise connectors and nearby wiring for damage, and test wiring for continuity between this harness connector and next harness connector back towards engine bay,
6. If situation is different, please send picture of wiring and connectors.

Late edit: Fuse for stop-lights is located in Junction Box behind kickpanel in footwell forward of LH Front door -- could check voltage here. Fuse is marked "STOP". However, if Fuse is blown, would expect no power at any of the three stop-lights, so not really expecting a problem here for LH stop-light when RH and High stop-lights are still working.

Wiring colour code shown in FSM:

 

[tjb]

Thanks for all this.

I only got as far as the second harness connection, and all I saw were green-yellow, black solid, red solid and yellow solid.

The only thing I had handy was a continuity tester for house outlets, and with the ignition on and the brake depressed that showed nothing anywhere.

The RH brake light is working so I tried the continuity tester over there and got the same lack of results.

I then plugged the RH combo light into the LH harness and … it worked.

I’m going to assume it is the Light/Lens. I found one at Fred Haas Toyota in Spring, TX, for $201 including shipping and ordered it. Wrong part. Ordered it from lexuspartsnow.com, $251 with shipping. $25 more than from Impex.

 

[tjb]

Just adding a postscript: it took three tries to get a lens that wasn’t damaged in shipping. The first two arrived in identical Toyota/Lexus packaging (from different vendors), with the same corner of the lens broken off. Definitely a packaging flaw - the bubble wrap didn’t protect that corner and the corrugated box was insufficient.

Second vendor checked the part before shipping and put the original box (identical to the first two) in a second box with additional bubble wrap.

Nobody objected to refunding, but if you’ve got to order one of these you can save some hassle by asking for the double boxing.