Shifter-lockout / tail lights problem

[flanker]

Hi folks,

I recalled from posts last year about a linked problem with the transmission shifter lock-out button and brake/taillight function. My girlfriend called to say that she suddenly couldn't take the shifter out of park without pressing down on the lock-out button.

Had her drive over and then checked the rear lights which weren't functioning. Rear turn signals DID work however. I wiggled the (3 per side) bulbs in their sockets but had no effect.Where should I start looking for a cause and what might be the cure???

Thanks in advance y'all!

Flanker'90 Q 202,000M+

[forecast]

it's the switch just under the brake pedal. The same switch activates both the brake lights and the shift release solenoid.

Check the fuses to start, that is likely the problem. (located both in-cabin and in the box next to the battery under the hood)

[flanker]

Hi Forecast, Thanks for responding. Found a blown 15 amp fuse located on the bottom right half of the inside cabin fuse block. It momentarily solved the transmission lock-out problem before burning the replacement fuse. The car was fine this morning, problem occurred during lunch hour. What are the chances of either some wiring chaffing under the shifter OR could it be a problem with a rear tail light bulb holder? Any other ideas?

Flanker

[forecast]

Fuse #13 (15AMP very bottom of right side)

Is the brake light fuse.

The wire goes through the switch at the brake pedal (it is a full current switch, no relay is used). From the switch the line branches

one side goes to a few control units - namely the power steering control unit and the shift solenid control unit, very little power flows through this branch (the power flowing through fuse 13 doesn't power either of these units. If the push button still relases the shift soleniod then the unit isn't at fault)

The other branch runs to the brake lights through a control unit that senses current flow (and signals burnt lights) and then to bulb holders. This branch carries enough current to potentially melt insulation on an aging wire.

Most likely the fault is at or in the bulb holders. Check them for melted plastic or wires. Also check the switch under the brake for melted wires.

Get an ohm meter and disconnect the harness at the current sensing module, check each of the four brake light circuts for shorts.

[flanker]

Hey Forecast, Thanks again for a thorough reply. I knew that the bulb holders are real sensitive with regard to electrical flow. The wiring going into the electrical connector for bulb holders looked OK but I should change them out to be on the sfe side. I hadn't messed with the lock-out swith next to the shift level. Is it a 2 position switch (On/Off)? It seems spring-loaded but doesn't "lock" into a down position. Press it down, it comes back "up" when you remove your finger. Wondering if this might be faulty as well. Thanks again for your time with this problem.

Flanker

[Q451990]

Is it a 2 position switch (On/Off)? It seems spring-loaded but doesn't "lock" into a down position. Press it down, it comes back "up" when you remove your finger. Wondering if this might be faulty as well.

That's normal operation.... sounds like it's working fine.

Did the tips on your bulbs look melted, or possibly the tips in the connectors look charred? If so that's your culprit. You might also check for CHMSL (Third brake light) for charred connections there too.

If not, it may be the brake lamp switch, although mine just failed (forewarned by a "pop" in the radio when I pressed the brake pedal sometimes). If you have a dead short that's taking out a fuse that quickly, you should be able to narrow it down to one bulb assembly by getting several fuses and unplugging one at a time until your fuse doesn't blow.

Heath