Brake light switch and neutral safety switch problems

CanadianBak'inSupra · 04-29-2010, 02:29 AM

my samurai did the same thing before i blew the engine...
would always die in between gears, i change the fuel filters and i cant remember if that fixed it or somthin else...
either way filter is like 8 bucks and mindless probly not a bad idea

cre · 04-29-2010, 02:47 AM

No Supra ever came equipped from the factory with a MAF.

I don't feel like going over it again so soon, so read here for the details:
http://www.toyota-supra.info/forums/82082-post15.html

Now that we know the difference it'd be a good start if we knew if the OP was running a VAFM (7M-GE) or a KVAFM (7M-GTE). The VAFM is fairly robust but it is a wear component. If the internal resistance medium is worn down excessively it will give the ECU air flow information which isn't accurate and may cause the engine to due when the intake drops sharply.

If it is a turbo MKIII then it's running a KVAFM which while not a wear component it is very delicate. Do NOT ever try to clean one with ANY liquid solution... compressed air, tops. MAF safe cleaner is just that... FOR MAFS! Now, if this is a GTE, you didn't try to clean the AFM, right? Haven't dropped it either I hope. Diagnostic info for both types are linked to below. There are more tests that can be done, but that's more than you usually need to worry about.

Another common part is the TPS (Throttle Position Sensor). It too is a wear component and it can be tested for flat spots and wear. Search Google for information on testing potentiometers for flat spots and I'm sure you'll find some details on the how to side.

The TPS also has a switch inside which tells the ECU that the throttle has completely closed so that if other certain criteria are met it will modulate the ISCV (Idle Speed Control Valve) properly in order to maintain the preset idle RPM.

A clogged ISCV will also contribute to these issues and it doesn't hurt to pull off the ISCV periodically and clean out any oil or greasy buildup.

Lastly.... vacuum leaks... check for intake and vacuum leaks.

TPS calibration:
http://www.cygnusx1.net/Supra/Librar...ction=FI&P=100

ISCV information:
http://www.cygnusx1.net/Supra/Librar...ction=FI&P=106

AFM information:
http://www.cygnusx1.net/Supra/Librar...ection=FI&P=94 (GTE follows GE)

As for the brake lights... test the switch under the dash that the pedal's arm comes in contact with... there's only one.

OP, post the specifics of your vehicle when you ask for help.... better yet, put them in your sig and profile.

CanadianBak'inSupra · 04-29-2010, 02:56 AM

thanks for the good reading links
(i know there not for me) but thanks anyways!!!

04-29-2010, 02:29 AM	#1
CanadianBak'inSupra Official hall monitor / search nazi - NO SOUP FOR YOU! Join Date: Oct 2009 Location: Canada, BC Posts: 837	my samurai did the same thing before i blew the engine... would always die in between gears, i change the fuel filters and i cant remember if that fixed it or somthin else... either way filter is like 8 bucks and mindless probly not a bad idea __________________ 1984 supra - 1uzfe - w58 - 4.10 - 1 piece aluminum shaft.

04-29-2010, 02:47 AM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	No Supra ever came equipped from the factory with a MAF. I don't feel like going over it again so soon, so read here for the details: http://www.toyota-supra.info/forums/82082-post15.html Now that we know the difference it'd be a good start if we knew if the OP was running a VAFM (7M-GE) or a KVAFM (7M-GTE). The VAFM is fairly robust but it is a wear component. If the internal resistance medium is worn down excessively it will give the ECU air flow information which isn't accurate and may cause the engine to due when the intake drops sharply. If it is a turbo MKIII then it's running a KVAFM which while not a wear component it is very delicate. Do NOT ever try to clean one with ANY liquid solution... compressed air, tops. MAF safe cleaner is just that... FOR MAFS! Now, if this is a GTE, you didn't try to clean the AFM, right? Haven't dropped it either I hope. Diagnostic info for both types are linked to below. There are more tests that can be done, but that's more than you usually need to worry about. Another common part is the TPS (Throttle Position Sensor). It too is a wear component and it can be tested for flat spots and wear. Search Google for information on testing potentiometers for flat spots and I'm sure you'll find some details on the how to side. The TPS also has a switch inside which tells the ECU that the throttle has completely closed so that if other certain criteria are met it will modulate the ISCV (Idle Speed Control Valve) properly in order to maintain the preset idle RPM. A clogged ISCV will also contribute to these issues and it doesn't hurt to pull off the ISCV periodically and clean out any oil or greasy buildup. Lastly.... vacuum leaks... check for intake and vacuum leaks. TPS calibration: http://www.cygnusx1.net/Supra/Librar...ction=FI&P=100 ISCV information: http://www.cygnusx1.net/Supra/Librar...ction=FI&P=106 AFM information: http://www.cygnusx1.net/Supra/Librar...ection=FI&P=94 (GTE follows GE) As for the brake lights... test the switch under the dash that the pedal's arm comes in contact with... there's only one. OP, post the specifics of your vehicle when you ask for help.... better yet, put them in your sig and profile. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar ---> Last edited by cre; 04-29-2010 at 02:52 AM.

04-29-2010, 02:56 AM	#3
CanadianBak'inSupra Official hall monitor / search nazi - NO SOUP FOR YOU! Join Date: Oct 2009 Location: Canada, BC Posts: 837	thanks for the good reading links (i know there not for me) but thanks anyways!!! __________________ 1984 supra - 1uzfe - w58 - 4.10 - 1 piece aluminum shaft.

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