HOW TO: Disable Tail Light Failure Warning Light for Lexus SC300/SC400
#1
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If you have replaced your normal bulbs with LED bulbs in your tail lights and now have that dreaded light on your gauge cluster then this is for you. LED bulbs in your tail lights do not draw as much power as normal bulbs so your car will think that you have burnt bulbs and will trip the tail light warning light. This is a simple, reversible hack and a much better alternative than taking off your gauge cluster and removing the warning bulb. This was done on my 1998 SC300 so be aware that the wire color may be different for earlier models.
Step 1. Locate your tail light ECU. The tail light ECU is located on the driver side quarter panel next to the antenna motor assembly. You will need to take off the driver side trunk trim to gain access to the ECU.
Step 2. Unplug the connector from the ECU and fish it out of the hole for easy access.
Step 3. With a flat head screwdriver pry up on the locking tabs located on the flat side of the connector. These tabs lock the terminals in place. This needs to be done to remove the wire terminal.
Step 4. Once you have lifted the tabs, locate the PURPLE WIRE with the WHITE STRIPE (If you have a 1992-1996 model the wire should be PURPLE with GREEN STRIPE). This is the wire that goes directly to the bulb on your dash. This is the wire you need to pull out of your connector to disable the warning light.
Step 5. Using a tiny flat head screwdriver, insert it inside the hole of the terminal and release the small tab that locks the terminal in place. Once you release the tab, the wire terminal will slide out from the back.
Step 6. Mark the hole the wire terminal came out of so you will know where to reinstall it in case you decide to reverse this hack. Now grab some electrical tape and securely wrap the terminal so it does not get in contact with anything. Plug the white connector back into the ECU and you are done.
Step 1. Locate your tail light ECU. The tail light ECU is located on the driver side quarter panel next to the antenna motor assembly. You will need to take off the driver side trunk trim to gain access to the ECU.
Step 2. Unplug the connector from the ECU and fish it out of the hole for easy access.
Step 3. With a flat head screwdriver pry up on the locking tabs located on the flat side of the connector. These tabs lock the terminals in place. This needs to be done to remove the wire terminal.
Step 4. Once you have lifted the tabs, locate the PURPLE WIRE with the WHITE STRIPE (If you have a 1992-1996 model the wire should be PURPLE with GREEN STRIPE). This is the wire that goes directly to the bulb on your dash. This is the wire you need to pull out of your connector to disable the warning light.
Step 5. Using a tiny flat head screwdriver, insert it inside the hole of the terminal and release the small tab that locks the terminal in place. Once you release the tab, the wire terminal will slide out from the back.
Step 6. Mark the hole the wire terminal came out of so you will know where to reinstall it in case you decide to reverse this hack. Now grab some electrical tape and securely wrap the terminal so it does not get in contact with anything. Plug the white connector back into the ECU and you are done.
Last edited by Luxor; 06-14-17 at 04:26 PM. Reason: poop
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miraluna (03-09-21)
#3
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Important knowledge. Sub'd!
Was definitely planning on converting to LEDs. This goes without saying, but LED set-ups for indicators could benefit from resistors so that you don't get super quick blinks.
Fyi, if you place the LED into its respective socket and you get no light, reverse the polarity by simply rotating the LED clock-wise 180° and place it back in. It should work.
For those who want to go the extra mile, Parts Shop MAX USA has this for synchronized signal blinking:
store.partsshopmax.com/universal/lighting/LRELAY.html
Was definitely planning on converting to LEDs. This goes without saying, but LED set-ups for indicators could benefit from resistors so that you don't get super quick blinks.
Fyi, if you place the LED into its respective socket and you get no light, reverse the polarity by simply rotating the LED clock-wise 180° and place it back in. It should work.
For those who want to go the extra mile, Parts Shop MAX USA has this for synchronized signal blinking:
store.partsshopmax.com/universal/lighting/LRELAY.html
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CurtK (12-28-23)
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Thank you so much. But what if you don't have LED bulbs and there is a warning light on the gauge cluster. Only when I turn on my lights. And all of your lights do work in the rear.
#11
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If you swapped your taillights the light out indicator will be triggered on the dash. Each generation of taillights has its own companion taillight module. Changing the lights but not the module will trigger the light, so in that case yes you need to do this mod if you want the light on the dash to go away.
If your car is all original, this could be an indication of the wrong wattage bulbs in the taillights.
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