1998 LS400 tail lamp failure displays/all bulbs replaced

[Zeus253]

1998 LS400 changed all bulbs to correct wattage or nominally higher wattage (1-3 watt above stock) and even electro greased connections. Still getting "tail lamp failure" message BUT ONE INTERESTING NOTE IS THAT IT ONLY SHOWS MESSAGE WHEN GEAR SELECTOR MOVES OUT OF "PARK". 

WHY would Lexus not make it easy to just replace bulb and done? 

Is there an easy fix?

[paulo57509]

False tail lamp failure is a known issue not limited the the LS. I've even had this issue with my '87 Camry that was no where near as sophisticated as the LS.  I traced the Camry's issue to a loose screw that connected a wire in the tail lamp failure sensor (TLFS).

Have you confirmed that both filaments in the stop/tail bulbs are working?

The TLFS is connected to side marker and license plate lamps.  You might want to inspect these bulbs and their function.

There are also two fuses related to the TLFS - 1) 25A Stop Lamp, and 2) 7.5A Tail Lamp.  Check these fuses.  I think one is under the hood and the other under the dash.  The 7.5A fuse feeds the marker and license plate bulbs.

The following is an extreme case.  This came from a member of another forum (member is based in Japan, so excuse his English):

"I'd check the tail light failure sensor located in the left side of the trunk. I worry that there is/are burnt trace(s). The photo below shows only cracked soldering points. But other than those soldering issues, it is the often case that traces that carry big current are tend to burn out. There are totally 8 brake related bulbs and the inrush current exceeds 40A or more when the brake pedal is pushed. Within 3 seconds, the current goes down to 13A or so but still its not a small current and repetition of the braking damages soldering points and traces. I'd say Toyota should had designed the board more robust and trouble free."

 

 

[RX400h]

Back in the early 2000s when I had a 2001 Corvette, I had to resolder joints on a HVAC digital display circuit board because the display blanked out. Perhaps suppliers had switched over to lead-free solder and didn't do enough temperature or current testing. Many Corvette owners faced the same issue. Another was a fading HUD when ambient temps climbed. I never fixed that one, but it wouldn't surprise me if solder joints were the culprits.

[paulo57509]

I had to reflow solder pads on the electronic brake control module (EBCM) on my '03 Safari.  Most all GM trucks that used this Kelsey-Hays system would get simultaneous BRAKE and ABS warning lights indicating a problem with the module.

Opening up the EBCM was not fun but it beat having to pay +$300 for a rebuilt unit.  I also had to source the proper heat sink compound, sealer for the module cover (GM got rid of the screw cover and went to gluing it on).

 

[RX400h]

I was lucky to be able to send my EBCM to ABSfixer.com for repair. It was $100 and thankfully, the board was soft-potted, unlike previous Corvettes. I would never specify hard epoxy as an encapsulant for a circuit board. 
A new EBCM would've been $1200 or so.

[Zeus253]

"RX400h" and Paulo, thank you all your information is greatly appreciated. RX..., yeah I have a 2004 Corvette also and the display for HVAC is extremely difficult to view (dimmed almost 100%). For the Lexus LS400 I haven't replaced the license plate lights or reverse yet. Didn't think those would apply to tail lamp failure. Also I believe I need to check the location of TLFS module in trunk area (not sure where that is). Previous owner did not bother to clean out trunk seal gutter so when I bought it water very easily could have drooled down into trunk inner sides behind carpet.