Brake light switch and neutral safety switch problems

[cre]

if you don't want advice. you're wrong about vacuum less affecting every range of output and there are no wires running to the shifter. After market BOSs can also cause what you're experiencing.

details on how to check diagnostic codes is posted in the FAQ, sorry, thought i mentioned that.

good luck with it. see ya.

[jtown125]

(CRE)......... I'm not trying to be mean or what not. I joined the forum list to have someone help me out. Your suggestions make no sense to me. I'm not someone who doesn't know anything about cars. I have been working on cars all my life. Vacuum leaks will cause a lot of things to go wrong. But if it was a vacuum leak it would struggle to die, same as a throttle position sensor and everything to that extent.

And neutral is neutral no matter what, a vacuum leak would affect it when it is sitting at idle just the same as it would be while putting it in neutral while driving down the road, your still running the same rpm's. I don't have a reader I said that. I don't know what bos stands for. I do know that the only thing that isn't stock is the cd player. Which could possibly have something to do with it if it wasn't wire up right...anything is possible.

Explain to me how a vacuum leak would cause it to shut off only after shifting up from 4th gear to neutral? A throttle sensor usually makes the rpm's go wacko whenever it is going bad. Thats why a sensor doesn't make sense to me...even though I can't check it in the first place... I could on the other hand, just go undo the neg. cable and reset the ecu. If it is a sensor the computer will erase it till it happens again.

These are the things that make most sense to me: A short in a wire, a bad ground, maybe even the clutch pedal sensor? (i would think it would mess up other than 4th to neutral though),

I drove it all day today. It died everytime after 4th to neutral. After 20 minutes of driving. I turned the car off, let it sit for about 15 minutes. And went off driving again. I tried to avoid 4th to neutral. But its a habit. The little time i did have it in neutral was shifting back down into second...and i drove for about an hour, and it didn't shut down once.

I don't like to waste time and money, i don't have money. And i need it to be fixed. But suggestions that don't make sense to me I can't see myself pursuing without a good explanation of how it would cause it to affect it in that way.

The only thing that made sense to me of your earlier post is the sharp drop in rpm's affecting the intake.

But y would it not die after pushing the turbo hard and letting off?
Like how you would break a motor in.
Going from +6 to 0 is a sharp drop to the intake,
unless it bypasses it some how. But turbo burns everything
over again, so I don't see how that is possible.

On the flip side of that with the intake pushing back?
Wouldn't a big amount of back pressure do the same thing?
3,000 to idle with to much back pressure...
i see that making it shut off...
the computer sees that there is to much pressure and
shuts it down.

On most of the new cars there is an Automatic SHUT DOWN Relay and switch....
But i don't think that the supra has one.

At the same time...Y only 4th to neutral?
The rpm's are still as high and the pressure will be still as much
shifting from 2nd back to neutral...but it hasn't shut off once like that.

What does the higher gear have to do with it?
If anything?

[btwilson86]

Originally Posted by cre

details on how to check diagnostic codes is posted in the FAQ

Originally Posted by jtown125

I don't have a reader I said that

Alright, a little bit of clarification:

I believe cre meant to type "BOV" and not "BOS", referring to an aftermarket Blow Off Valve.

Checking codes on MKIII Supras does not require the use of a code reader, just a jumper wire or a paperclip. As stated above, details on how to check codes are here in the FAQ. Once again, keep in mind that just because the CEL is not on it doesn't mean that there are no error codes stored.


When you do the 4-N and 5-N shift, will it still die if you accelerate at partial throttle without boosting? Does it do it under half load? Full load?
Also, does it cut out regardless of what engine RPM's you shift at (lo vs hi)?

[btwilson86]

Oh, one other thing....

You're saying it's shutting off. Is just the engine shutting off, or does all electronics shut off?

[jtown125]

give me a second....

[jtown125]

Alright...

It does have a BOV. And it wasn't doing was it was supposed to do...how would it cause the car to shut off immediately?

I don't think that the rpm's have anything to do with the car shutting off. I could be wrong.

I took it out again after the last post and it died stopping from 3rd-N too....

but it has yet to shut down from 1-N or 2nd-N. And im always shifting anywhere from 2500 to 3500 rpm's.

Of course when since the gears are high in it i usually just leave it in 4th when going 40 mph. running 2500 or a little higher and then putting it neutral.

With the engine only having 3,000 miles on the rebuilt motor all of these things that people are saying aren't making any sense to me. They are the original parts though, so wear is def possible.

It hasn't died from full boost and quick let off of gas... BOV still does what it is supposed to do...from what I can hear.

I don't know if back pressure has anything to do with it...but the down pipe has 2 pipes and one is cut off. Which would cause a lot of backpressure.

It "dies", it just does it without any hesitation. my def of dying is chug chug chug chug....die....

All the warning lights will come on and i just put it back in gear and remove the clutch...

[jtown125]

And i don't know about the electronic things...i would assume they stay on...the cd player don't work half the time so it usually stays off.

[btwilson86]

Okay, I'm starting to suspect the BOV.

Stock turbo supras came with a bypass valve instead of a blow off valve. Biggest difference between the two is that the bypass valve will redirect excess boost pressure back into the intake pipe between the AFM and the turbo, meaning all of the air stays in the intake system and is accounted for by the AFM. Blow off valves vent the excess pressure to atmosphere. Our computers are programmed to "expect" that air to stay in the intake system, so if it is vented to atmosphere the engine will briefly run rich after shifting (which can cause it to chug and die) because it anticipates more air in the intake than what is actually there.

Basically, as far as the computer is concerned, each time you shift your BOV creates a giant boost leak. The only reason I can think it does it in the higher gears is because it takes longer for the RPMs to get there, allowing you to build more boost pressure thus loose more air/pressure when you shift.

[btwilson86]

Originally Posted by jtown125

And i don't know about the electronic things...i would assume they stay on...the cd player don't work half the time so it usually stays off.

I suspect that since the warning lights come on, it's just your engine cutting out and not the entire car. This also makes me think it's not as likely to be a bad ground or a short

[jtown125]

One thing i do know...IT DOES RUN RICH!!! lol

So, lets go ahead and say its the blow off valve. Y would it not die after boosting in a single gear?

And to fix it?