1991 Lexus LS 400 tailight "telltale" illuminated

CBEARING

MEMBER
1991 LEXUS LS 400
V8
2WD
AUTOMATIC
147,000 MILES

"tailght bulb out" indicator is on all the time-all bulbs are good however both backup lights are barely glowing when the car is in reverse.
Step on the brakes(even with key off) and the "R" for the gear select indicator reverse position comes on even when in drive or any other position. When the break is applied at idle, the engine speed drops as though the alternator is really being loaded by a dead short or something really sucking current. Sometimes when driving, a light application of the brakes with no change in pressure produces a sudden deceleration as though antilock or some other brake action "kicked in"

1 Reply

KHLOW2008

MECHANIC
41,814 POSTS

Hi cbearing,

Thank you for the donation.

There are a few possibilities for the problem.

1. Bad ground circuit. Check the rear taillights for bad ground connections, remove, clean and retighten them to test.

2. Faulty light failure sensor. Item is located on RIGHT side of luggage compartment. Check if it is contaminated due to water entry.

3. Shorting of wiring harness. Check the harness near the rear boot hinges, they tend to short due to repetitive opening and closing of the boot over time.