texasbigdog Posted April 7, 2008 Share Posted April 7, 2008 Help...I have a warning light on my dash illuminated and the owners manual says it indicates the rear tail lights are bad. However, they are not..running lights, brake lights and turn signals all function perfectly.. Anyone had this problem - false warning? How did you resolve it? Thanks TexasBigDog Quote Link to comment Share on other sites More sharing options...
TA in KC Posted April 7, 2008 Share Posted April 7, 2008 There is a wire harness that is attached to the left hinge of the trunk. Over time, repeated opening/closing of the trunk lid can cause those wires to break. It can cause a variety of different things, your issue being one of them. Open the harness up and you will probably find a broken wire. Once that is fixed, the light should go out. Quote Link to comment Share on other sites More sharing options...
1990LS400 Posted April 8, 2008 Share Posted April 8, 2008 There is a wire harness that is attached to the left hinge of the trunk. Over time, repeated opening/closing of the trunk lid can cause those wires to break. It can cause a variety of different things, your issue being one of them. Open the harness up and you will probably find a broken wire. Once that is fixed, the light should go out. I know this was a common problem on the 90-94 LS400, but is this also happening on the 95 and up LS? I'm not saying it is not, but I don't remember seeing a thread about this problem occurring after 1994. It is certainly worth checking out. I had a similar false warning light for several years on a 90 LS400. The problem turned out to be a loose connector on an aftermarket trailer wire harness. If you have not changed all the rear bulbs, I suggest you do. You might be surprised how blackened some of the bulbs will be and it is possible that there is a loose filiment in one of the bulbs. Also, check the ground connections for the rear lights -- see if they are tight and if there is any corrosion. It could be the rather expensive module that senses that a bulb is out but failure of that seems to be quite rare. It's probably something simple. Quote Link to comment Share on other sites More sharing options...
mttls400 Posted April 8, 2008 Share Posted April 8, 2008 I have 92 ls400 and she has the same problem - thank you all - i will check the wriring and report later Michael Quote Link to comment Share on other sites More sharing options...
eatingupblacktop Posted April 8, 2008 Share Posted April 8, 2008 I'll go with 1990 on this one. If your wiring bundle checks out and the bulbs are ok, corrosion is the likely culprit. Even slight corrosion will increase resistance and drop the voltage enough to trigger the warning light. Cleaning the socket and bulb with some fine sandpaper or a plumber's pipe brush will probably fix your problem. Quote Link to comment Share on other sites More sharing options...
RCRFAN3 Posted April 8, 2008 Share Posted April 8, 2008 Check the third brake light bulb, that's what it was on my 98 Quote Link to comment Share on other sites More sharing options...
wwest Posted April 8, 2008 Share Posted April 8, 2008 I'll go with 1990 on this one. If your wiring bundle checks out and the bulbs are ok, corrosion is the likely culprit. Even slight corrosion will increase resistance and drop the voltage enough to trigger the warning light. Cleaning the socket and bulb with some fine sandpaper or a plumber's pipe brush will probably fix your problem. And while you're in there check to see if metal "cold flow" might be the problem. Due to spring pressure and time the soldered (lead/silver) connection for the bulb will "cold flow", from a rounded/raised connection into a flat or concave connection. Quote Link to comment Share on other sites More sharing options...
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