Brake lights come on with headlights

Brake lights come on full with headlights on,With headlights off ,the dash,radio,clock light up when brake pedal is applied

Interesting problem. First thing to do is find the ground for your tail lights and re-attach it. I suspect that your tail lights are grounding through your brake light bulbs.

25 years ago, Toyotas used to ground their tail lights with a wire from the passenger side tail light harness to a screw in the chassis beneath the plastic cover back in that corner of the trunk.

Where they put the ground these days is anyone’s guess.

This kind of trouble typically happens with dual filament bulbs. One of the filaments crosses with the other of the two different circuits and they do just what you stated. Check the rear brake light bulbs for a crossed filament.

I’d like to add that it maybe a badly installed tail light. The dual filament bulbs also have a staggered lug, the method they tried to use to make sure the bulb only goes in one way. I’ve seen people manage to jam the bulbs in backwards anyway, causing the connectors to cross and cross-feed to circuits.

Either way, chances are 99% the problems are all at the tail/brake lights.

There has been no bulb replacement in probably over a year,I went to the library for a wiring diagram trace and i could not find a 93-4 manual,Any other input would be appreciated,Thanks

What is the year model, etc? I’ll look for a wiring diagram.

94 Toyota Corolla DX ,With the 1.8 automatic

I chased a similar problem on a Chevy Lumina. The ground wire in the trunk had been broken loose by stuff being jammed into the trunk.

Headin back out in search of that ground wire again,Thanks !

Check out these drawings.

ok well from what i understand from these diagrams is the blk-white is the ground? ,I stripped a section of that in the trunk from the main harness before it branched out for the tail lights,I then drilled a small hole in metal and tightened the bare part of the wire with a bolt washer also,and still the brake lights come on with the parking-and headlights are switched on,If anyone sees another color wire being the ground near the tail lights please let me know,Thank You for these diagrams bennyandthejets

To see if this problem is being caused by one of the rear lights disconnect one at a time and see if the trouble clears. If the wires to the rear lights are going to a socket there may be trouble with one of them. Somehow current is bridging from the brake circuit to the running lights. The trouble may also be with the wiring before it gets to the rear lights, some insulation may be damaged and the circuits are bridged. If you don’t find the trouble at the rear lights then you will need to back track the wiring looking for damage to it.

I wont be able to get to that till tomorrow night to try some more,Thank You for the follow up and i will get back with with any results

I Just Got It !!! I took out the rear lights and did a visual of each bulb,Here i found one had a filament that bridged and connected with the second filament,(1157 bulbs has 2 filaments),Im surprized a fuse didnt blow to pinpoint this easier ,Anyway,Thank you ALL for your input : )

Thanks Cougar,As i just posted this was the problem,In all my car years i never seen this happen where the 2 filaments bridge together,