Scion tC Forums banner
21 - 40 of 51 Posts

·
LED Maniac
Joined
·
2,967 Posts
i just use it without the wrench. it shouldn't be torqued crazy enough to where you need to attach the socket to the ratchet.

if you're still having trouble.. the "special kind" would be a deep socket.
 

·
Registered
Joined
·
136 Posts
I just finished this thread it didnt fix mine. I heated the posts on the opposite side of the wiring plug. Did the trick for me. thanks engifineer :D
 

·
Destroyer of Cones
Joined
·
7,066 Posts
Discussion Starter · #26 ·
Yours is probably one of the more rare issues then, since so far this has fixed all the 07 issues I have encountered.

But the harness pins fixing it means the dimmer circuit pin was probably the culprit, which would cause the same issue as the transistor. Glad you got it fixed!
 

·
Registered
Joined
·
1 Posts
Another 07 Tc owner who would like to say thank you...I followed the directions and this fixed the HVAC lighting issue. Going to do the LED conversion next...
 

·
Registered
Joined
·
7 Posts
I have the same problem.
I'm gonna try this tomorrow after work.
but one question, will this also solve the problem of my clock getting reset after I turn off my car?
and can I still put the LEDs after I fix this?
 

·
Destroyer of Cones
Joined
·
7,066 Posts
Discussion Starter · #30 ·
Clock being reset is likely a different issue. My guess is that for some reason, the constant bat + connection to the unit is for some reason a switched (acc) supply. Either that, or there is something that is affecting its memory voltage on the board. Hard to say.

You can do the led swap after though. This fix is a proper fix, in that it corrects a bad factory solder joint. So everything on the board will be as stock when you make the fix. So you just do the led swap as normal.
 

·
Registered
Joined
·
7 Posts
Clock being reset is likely a different issue. My guess is that for some reason, the constant bat + connection to the unit is for some reason a switched (acc) supply. Either that, or there is something that is affecting its memory voltage on the board. Hard to say.

You can do the led swap after though. This fix is a proper fix, in that it corrects a bad factory solder joint. So everything on the board will be as stock when you make the fix. So you just do the led swap as normal.
Good News!!:)
soldering the T302 also solve me the problem of my clock resetting, air conditioner resetting, and ofcourse all the lights of the buttons and the clock light. Thank you SO MUCH dude.
you just made me save like $500.:eek:
 

·
Destroyer of Cones
Joined
·
7,066 Posts
Discussion Starter · #32 ·
Good deal! I guess no one ever mentioned that issue along with the lighting issue. I would have to figure out why they tied those two circuits together, but if that fixes it then its a win either way.
 

·
Registered
Joined
·
12 Posts
My HVAC lights died tonight :(, and I just found the "root cause" of the cracked solder on T302... (Yay! :D) It's not actually due to poor solder on the transistor, and there's a VERY good chance that it will break again if only re-soldered. The real problem (yes, T302 *is* the main issue, but it's a symptom, not the cause..) is with the front panel, where the circuit board attaches to.

If you look at the back side of the panel - to the bottom right of where the Hazard switch would poke through, you'll see the real problem. There's an "extra" square plastic box which leads to an empty hole on the front of the panel. Nothing goes there, but it looks just like the other "boxes" that are for the indicator lights for the other buttons. My guess (and it's only that, of course..) is that an earlier revision of the control panel had a status / indicator light for the Hazard button there. An engineer (or a bean counter guy, or maybe for some other valid reason like "who needs a status light when your turn signal LED's are blinking??) decided to remove the indicator light, but since the panel molds had probably already been created (for $50k +) they didn't remove the little box. It's not in the way, right???? Yeah, someone should have told the circuit board design guys..........

That little extra "box" comes *right* down on the side of T302, and also smashes down the solder on R318 and R319... (see close-up pics...) My T302 had plastic shavings on the side of it and on the circuit board, and the solder on those resistors was smooshed over. Hmmm.... Something going on there, and it's not right! I noticed the little box just about lined up with the parts, so I put a piece of electrical tape over the parts and drew some silver Sharpie on the tape. Put the board back in place, and sure enough, silver Sharpie on the plastic box. So, the "full" fix should be to re-solder T302, probably R318+R319, maybe T303 just in case, then CUT about 1/8" off the bottom of that stupid extra box... Otherwise, over time the box will rub on T302 again and potentially break the solder again. (unless you really glob it on there! :) LOL! )

I would almost go so far as to say this should be done to all early 2007 cars as preventative maintenance, or should be a recall or something.. (got mine in 11-06, did the blue LED swap not too long after) I did buy some Black Cherry matching paint a few months back, maybe it's time to paint my center console parts now... LOL

I'd be willing to bet the newer HVAC's either have that box removed, or those parts have been placed a little more carefully... Maybe I should check all the other boxes too! :p Hey, I've been burned by this at work on my own circuit board design, I didn't notice a power trace too close to a screw hole that was then screwed down onto a grounded metal standoff... Poof.

Ok, that's all I've got... I took some pictures for a step-by-step show of what I did......




















 

·
Destroyer of Cones
Joined
·
7,066 Posts
Discussion Starter · #34 ·
Interesting find, but I have checked for those type of things on a couple and did not find it.
Not saying this cant help the issue along, but there was definitely a cold solder joint on the ones I have fixed so far (could be found by inspection with a magnifying glass). But, it is a good idea to check for this as well. My guess is that the poor joint was agitated loose by the contact from the front panel.

Good find!
 

·
Registered
Joined
·
12 Posts
I took a look online for pictures of 2007 boards, I found some posts from late 2006 that show the board with the parts in the same spot. Unless they changed the mold for the front panel (doubtful due to the ridiculous cost of high-volume injection molds) any controller with the components in that spot on the board will be damaged by the extra plastic. There are no coincidences in electronics engineering.. LOL The broken solder joint on pin 1 of my T302 looked to be just cold solder (and I probably would have just cursed the bad solder job, reflowed it, and stuffed it back together), until I realized something must have caused it, and saw that it was being directly pushed on..

No magnifying glass here, but I do use a 30x microscope. :D

I just took apart a spare '06 unit, the front panel plastic is the same (useless light box present) but there are no parts there to break. I couldn't find any pics online of 2008 boards, but I assume they noticed the problem by then and moved the parts. Much cheaper than new molds. I'm guessing that Scion ordered these in the 10,000 at a time range, so there's got to be at least that many out there with the box pushing on the side of T302.. Loose contact with the front panel would actually be a good thing in this case, to take pressure off the transistor.
 

·
Registered
Joined
·
1 Posts
Great thread, thank you! I just picked up my first Scion from the stealership and of course find this issue tonight but with your thread I'm glad to know I don't have to worry about going back to that place!
 

·
Registered
Joined
·
6 Posts
Do the HVAC lights going out have any correlation to the lights on the dashboard and the gear shift? The lights on my HVAC, the lights in the compartment under the HVAC unit, the lights on my gearshift AND the lights on the dashboard (speedometer, RPM etc) all went out. The box with the odometer still works but everything else isnt and the dial doesn't work either.
 

·
Registered
Joined
·
12 Posts
This particular problem with the broken solder on the T302 transistor shouldn't cause the other lights to go out.. I believe the actual light dimmer circuit is built into the speedometer cluster? The odometer light normally comes on when the other lights are off, so it sounds like the dimmer control has gone bad, or maybe it's not getting the "headlights on" signal to actually turn everything on? Ever have any work done or any problems with any lighting in the car?
 

·
Destroyer of Cones
Joined
·
7,066 Posts
Discussion Starter · #39 ·
You likely have a short or over current issue that popped a fuse. The dimmer control signal comes from the gauge cluster, which in turn dims the rest.
 

·
Registered
Joined
·
8 Posts
I just got a 2007 TC with 38000 miles

Having the same problem, the radio lights and clock and temperature lights go off when the headlights are turned on.

I tried the HVAC resolder fix of the t302 but that did not fix it

Can anyone help? Im pretty sure the previous owner had an aftermarket radio in there but switched to stock when he traded the car in
 
21 - 40 of 51 Posts
Top