Gas cap vent vs brake light switch
11-29-16, 10:54 AM
#1
Driver School Candidate
Thread Starter
Gas cap vent vs brake light switch
2007 RX 350: After reading through abs/trac/brake/vsc Christmas tree posts, I'm wondering about the difference between the common gas cap nuisance and the brake light switch problems. I'm traveling at work for a few days, so I'm researching the problem to fix upon my return.
It's my understanding that the brake light switch has both a Normal Open and a Normal Closed switch (hence 4 terminals), so you can't just diagnose it with "if brake lights don't work" since those are driven by the normal open side, and other systems monitor the normal closed side too. I have a new brake switch in hand and ready to install, but I would love to read the codes first
Does the switch set a code? Is there a way to read those codes by jumping terminals, if so, does anyone have a guide?
As far as the gas cap goes, my other cars (Acura/Honda) always vent a good puff when I open the filler cap, but I don't notice it with the RX. Does the stock cap have an internal vent, or should it puff when I open it? I can throw 20 bucks at preventative maintenance, but the seal on the cap looks perfect and I'm 1.5 hours from a dealership (I want the tether, not the cheap cap from AutoZone).
I don't have a CEL code stored, nor does it come on when I get the Christmas tree for vsc/brake/abs/trac. If those light up, turning the ignition on and off fixes it for a few days. I know this has been covered, but some of the posts I read confused me.
Thanks for any advice!
It's my understanding that the brake light switch has both a Normal Open and a Normal Closed switch (hence 4 terminals), so you can't just diagnose it with "if brake lights don't work" since those are driven by the normal open side, and other systems monitor the normal closed side too. I have a new brake switch in hand and ready to install, but I would love to read the codes first
Does the switch set a code? Is there a way to read those codes by jumping terminals, if so, does anyone have a guide?
As far as the gas cap goes, my other cars (Acura/Honda) always vent a good puff when I open the filler cap, but I don't notice it with the RX. Does the stock cap have an internal vent, or should it puff when I open it? I can throw 20 bucks at preventative maintenance, but the seal on the cap looks perfect and I'm 1.5 hours from a dealership (I want the tether, not the cheap cap from AutoZone).
I don't have a CEL code stored, nor does it come on when I get the Christmas tree for vsc/brake/abs/trac. If those light up, turning the ignition on and off fixes it for a few days. I know this has been covered, but some of the posts I read confused me.
Thanks for any advice!
12-01-16, 05:45 PM
#2
Lead Lap
Gas cap problem is emissions related so it will give check engine light and vsc. Mine went bad and also gave OBD2 code P0456, small evap leak. New gas cap, unplug/replug negative battery cable, no more code. Have someone stand behind your car to see if your brake lights are coming on, or back into a spot in a dark garage or something and test your brake lights. How many miles on your RX?
12-02-16, 07:04 PM
#3
Driver School Candidate
Thread Starter
120K. I'm pretty convinced that it is the brake light switch, although the brake lights seem to always work. Either way, I have the switch in hand and it is going to get replaced tomorrow. I'll try to disassemble the old swtich and see if there is a broken solder joint or bad contacts.. I will post pics if I can get it apart without destroying it,
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