93 Ls, Check Engine, Abs, And Parking Brake Lights All On...

[control_is_dead]

As the title says the check engine, ABS, and parking brake lights are all illuminated when the car is on, as soon as it starts. There are no codes so Im guessing something isnt connected or lost connection, but I dont know where. It doesnt seem like a sensor malfunction since the lights are on right away and not giving off any codes. Ive been through the rats nest under the dash and all connections to the ecm, abs, and trac units look fine. The car also didnt want to shift into 3rd gear, it seemed to do 1&2 fine but didnt go above 2000rpm. Im going to try and narrow down what all three systems have in common. The parking brake would probably be easiest to start with.

If anyone has had any similar problems with lights or shifting, your help would be appreciated.

[1990LS400]

It may sound silly but the very first thing to check on a 90-94 LS400 when electrical gremlins arise is the electrical wiring harness at the left trunk hinge. Wires in the harness at the hinge tend to break over time as the trunk lid is opened and closed. The shifting problem due to broken wires at the hinge is very common. I've lost track of how many times I've seen this problem reported. It occurred on the 1990 LS400 I used to have in the summer of 2003 and the person who bought my 90 LS from me had to repeat the repair at least once..

After you unravel the tape from the harness wiggle each wire separately to determine which ones have broken cores. It's best to solder in short lengths of wire to repair the broke wires. Wrap each repaired connection with electrical tape.

Let us know how it turns out. I think you will be surprised at what you find when you check the wires at the left trunk hinge.

[control_is_dead]

ok, thanks ill check those out asap. do you remember if you had warning lights on when you had the issue on your car?

[control_is_dead]

I probed all the wires at the trunk hinge with a multi meter and everything seems fine. The only things on this circuit are the rear lights and trunk latch, unless your referring to the harness that runs by the rear strut tower?

[fsuguy]

Do other indicator lights such as radiator, oil, battery, etc., also come on? I had an issue where all these indicators lit up when my alternator bit the dust. Replaced the alternator and all was well again. Of course, if the issue with the left trunk lid hinge wiring is the problem, you will experience a host of odd problems since it appears that some signals associated with the ECT and shifting are linked to the wiring going to the brakes.

HTH