brake lights out - what next?

[magnetbox]

Hi, I've got a '94 4.0L 2WD, 216k.

I noticed that all three brake lights aren't working. Running / parking lights are fine, though.

- Fuse is good.

- Switch connector shows 12.1v on the multimeter.

- Replaced brake light switch.

- Opened taillight housing and found that both top 3157 bulbs were a little blackened. Replaced both, and the brake lights still won't work.

What should I check next? The bulbs hadn't been changed in at least five years.

The originals were Sylvania 3157k and I replaced 'em with plain old 3157 bulbs. Could that be the issue?

 

[adsm08]

Ks are just a bit brighter, they should work fine in that socket.

Unplug your brake switch and put a jumper wire across the pins, see if the lights work then. If so, you either have a bad or misadjusted switch.

If not, check resistance from the switch to the sockets.

 

[magnetbox]

Thanks.

I jumped the connector and got nothing.

The new 3157s light up when I turn the running / parking lights on, so I imagine it's not a bad ground. Gotta be the switch or connector.

 

[magnetbox]

I'm baffled. It almost seems like the brake lights are on all the time when I switch on the running lights / headlights. Is it possible for anything in the chain to fail closed?

I just replaced the pedal switch, so unless I got a defective one...which I sorta doubt...

You see, I had running lights prior to this. Found blackened 3157 bulbs when I pulled the lenses. Now my taillights are bright, so I think both filaments are on.

If it helps any-- I've also had trouble lately with my rear brakes locking up at relatively low speeds, in any condition. Any time I need to come to a relatively abrupt stop, one side seems to lock up a little. Could this be related? I changed the pads about four years ago but have only put about 30k on the truck since.

 

[rangerluver]

I had my brake lights fail and the parking lights still worked. Others have posted this problem too in the past so it is a common problem, although maybe not yours. In the back of the wiring harness under the bumper is an area that seems to be susceptible to wire fatigue. I had the brake wire break about an inch away from the little black box and had to butt connect it together again. A pain but not too bad. A mech actually told me to look there and others on this site have had the same problem.

Hope it works.