Diode in brake light circut

Interesting idea. But would not blocking the BOO from the PCM also effect some other engine control functions too?

DC

You are being mislead. You simply need to relight the pilot light in your turbocharger and put a 1 can of lighter fluid in the fuel tank.

You were complaining about the turn signals causing the tc to unlock. Put the diode between the brake switch and the brake lights to prevent current from the blinkers from coming back down the line to the brake switch and energizing the line going to the engine that normally disables the tc lock when the brake is pressed. I'd probably put the diode as close to the lights as possible so I'd be sure of it.

The real answer is to correct the problem and don't worry about diodes. If using the turn signal is causing the TC to unlock, it is because you have lost the ground in one of the turn signals. It will then feed back through the brake light. When the brake light circuit has voltage applied, it will disengage the TC.

Since the brake lights and turn signals use the same bulb element, what prevents it from feeding back no matter the state of the ground?

Oooh, oooh, let me answer this one. The turn signal switch prevents that. When you're giving a signal, the bulb that's signaling no longer functions as a brake light. Have you noticed that? There are contacts in the turn signal switch for that.

OK, I think I've got it now. As soon as the weather warms up I will:

2} Find the brake Light hot wire. This will involve wife stepping on brake, another old person in the mix.

4} Solder in diode, current allowed to flow to lights.

Question, I will probably resort to Radio Shack for the diode, is there a specific value? Any clues would be helpful.

The bulb in use is a 3157K. At

Maybe the guy's real problem, then, is a bad turn signal switch?

Interesting, but not exactly how electricity works. There may still be a voltage on the brake line even with a decent ground, that's why a relay is sold to keep the turn signals from energizing trailer brake controllers.

given the following conditions:

intact filaments good ground non-faulty brake switch

please tell us how there can be 'a voltage on the brake line even with a good ground'

Or better yet, fix the faulty ground! Why would you take that Jerry-Rigged approach to fixing your problem? Your diode fix is like adding another valve under your kitchen sink instead of fixing the leaking faucet... If your old body and/or mind can't do it, take it to a competent automotive electrical repair shop.

Define good. In modern vehicles, there really isn't one unless it goes directly back to the battery.

'good ground' = at same voltage potential as battery negative

now...........can you explain that bit about 'in modern vehicles...........' ??

I'd qualify that with 'at the same potential at operating conditions' ie with normal current present. Since voltage is a function of current and resistance, it can change. A good ground needs to have a near-zero resistance path to battery negative. Even the frame will show a potential difference from battery negative when turning the starter over.

As far as the modern vehicle comment, I don't have a clue what that means.

Stephen

"Modern vehicle?" I don't think Chris Hill has a clue either. He got an excellent explanation of what was causing the problem. In the process, it was pointed out that the taillight/brakelight and turn signal bulb has a dual filament, contrary to his belief. At this point, I think he is simply trying to direct attention away from his improper description of the circuit and how it works. Some people just have a hard time admitting they were wrong.

Nothing like a good strawman to give noodle like strength to an argument! Admittedly though, some wierd things can happen with that dual filament light system.

Stephen