View Full Version : ST185 Clutch Safety Switch

03-27-2007, 06:37 PM
Back int he day, my shop was slow, so I had one of my installers put in a Compustar remote start/alarm since i was paying them to basically stand around. Now, the proper way to bypass the clutch safety switch would have be to have relay that was triggered by the remote starter brain to interrupt the switch to mimic a depressed clutch pedal to get the car to start. More on this later.

Sometime around the time my remote starter was installed, my cruise control went out. I never put two and two together, but if you are still following this wordy question thread, my installer permanently disabled the switch by mimicking an always depressed clutch pedal state. Since the car things the clutch is depressed, the Cruise Control cannot work. Gah!@ So simple of a problem.

I want to get my cruise back up and running, but I have no idea what a perfect ST185 switch and switch wiring look like. I cannot make heads or tails of the wiring diagram either. Since I have limited time to work with crap under my dashboard with having the back from hell, I was hoping I could get some pictures.

Can anyone tell me the correct location and colors of the wires and connectors for the ST185 Clutch Safety Switch and/or provide pictures of the switch wiring and connectors. I think I see mine, and have tried to plug it back in, but the clutch still acted as being depressed. There has to be a ground in the wires still.

Nobody ever likes a permanently depressed clutch.:( Please help make it undepressed.:D

03-27-2007, 07:01 PM
The location it comes from is above the fuse box out of the harness bit there as you can see below. I marked the wires with a yellow line and circled where they come out of the bundle. As for the colors, don't know if they would be the same as yours, but mine are black and white/black from the bundle to the connector and green and green/orangishbrownspot going to the switch. I've got mine running to a microswitch mounted to the shifter assembly that closes the loop when in neutral. Hope this can get you started at least.

03-27-2007, 07:10 PM
switch should be a simple 2 wire design, you might want to wire a simple on/off switch to it so when ever you want to use the Cruise control you can turn it on/off. You will have to remember to click the switch to on/depresed in order to use the auto-start and then to flip the switch back in order to use cruise control.

03-27-2007, 07:17 PM
^That would defeat the purpose of it being a "safety switch", it would still have no way to tell if you were in neutral.

03-27-2007, 08:09 PM
Thanks for that. It does help. I am hoping that the trac is the same. Can you show me the path of the "to switch" portion of the wire and the switch itself? As long as I know where every thing is right off the bat, I can get in and out:hehe: :D

03-27-2007, 09:04 PM
I don't remember what the switch looked like, I threw it out long before I even had the remote starter, I hate having to push the clutch to start the car, manufacturers should incorporate the safety into the shifter.

Anyway, I have 2 pics below, one with scribbling and one without in case the scribbles are in the way of something. Basically, the wire just ran around the wall to the switch mount(hot pink line). I circled one spot labeled connector clip that I think is where the connector stuck to, not sure though. The mount is right behind the pedal on the wall. There is another switch of some sort on the driver side of the pedal arm, but I have yet to figure out what it is.

(BTW, since you are an audiophile, can you check out my thread about 4" in the A&E forum and let me know quick :bigthumbu )


03-28-2007, 01:33 AM
Not to go OT, but I wonder if there's any way to incorporate a safety mechanism onto the shifter to ensure the car is in neutral. I want to get remote start at some point but I'd like to have the insurance it would offer.

03-28-2007, 01:42 AM
the car does NOT sense that its in neutral, it senses when the clutch is pressed in or not. When you install the auto-start you MUST by-pass that function, its actualy illegal in some states to install auto-start on all stnd. cars and good luck finding an installer to install that on a stnd. car on the states that will let you.

As long as you train yourself to always use the parking brake and leave the car in neutral you should be fine.

03-28-2007, 02:04 AM
^ I installed mine myself :bigthumbu You won't find an honest installer who will do it in ANY state cause it would void the warranty of the system before it broke any laws.

:laugh: You might think you can "train yourself", but that's a pipe dream, that's how mine ended up running over my gas grill and stopping about 2 inches from my house with the grill in between after I'd had it for almost a year. No matter how hard you try you always fuck up once in a while. Thus the need for a "safety" switch. Or more appropriately called a "failsafe".

The car doesn't "sense" that the clutch is in either, it just knows that an open loop has been closed and its okay to start. That's why I said manufacturers should have incorporated this into the shifter instead of the clutch.

Not to go OT, but I wonder if there's any way to incorporate a safety mechanism onto the shifter to ensure the car is in neutral.
If you reread, this is what I did with the microswitch mounted on the shifter base. Basically, when it's in the neutral position, it hits the switch tab thus closing the loop. I read somewhere else around here a while back where someone did this with a reed switch also. It can be done!:D

03-28-2007, 02:26 AM
So how did you incorporate it into the wiring? Did you just basically incorporate it into that loop you talked about rather than the clutch safety switch?

03-28-2007, 02:51 PM
grayscale, can you take a pic of your microswitch install when you get the chance. I will check out your thread as soon as I can. Not avoiding it... I just didn't log in last night. When to go see "shooter" will my son and my mom.

03-28-2007, 11:36 PM
Cool mom :cool:

Yea, I'll get one when I can, it's hard to see without pulling it all apart, but basically I have a microswitch with a long contact arm on it and I just extended the clutch saftey switch wires to it. When it's in neutral the shifter depresses the contact closing the loop. For mounting, I cut into the metal base that's attatched to the tunnel and made a little hole big enough for the switch to fit through. Then I welded a little piece on outside the hole to screw it down to- so the arm sticks through into the area where the very bottom portion of the stalk is. I'm sure there are probably more ways to do it without any welding too, particularly if you go and buy any switch you want, I did it that way cause I used a switch I already had laying around. But yea, I'll get you a pic when I can. I need to pull my interior soon anyway, I want some new carpet, I got holes under the driver heel area!

04-03-2007, 01:00 AM
Here is a good type of micro switch to use-
http://cgi.ebay.com/ebaymotors/NEW-MSD-SINGLE-POLE-DOUBLE-THROW-LEVEL-OPERATED-SWITCH_W0QQcmdZViewItemQQcategoryZ33693QQitemZ2200 97958380

04-14-2007, 08:31 PM
After going through 3 different types of set ups with microswitches and finding flaws and failures in each of them, I have come up with the best solution that I can find. The following does require the plastic shift base and not the cast steel one. Basically the switch makes use of the guide piece at the front of the shifter base that slides back and forth when you shift. The reason for using this as opposed to other places is that the movemt here is always in one direction. The piece slides in a tube, and the tube must be trimmed back to expose the guide. Cut it in half lengthwise and then as far back toward the shifter as you can without cutting into the guide itself. Now that you have the guide exposed you can see that it has three positions when moved. There is a central pos. when the shifter is in neutral. When shifted into1st/3rd/5th the guide slides back towards the rear of the car, and when in 2nd/4th/R it slides forward toward the front of the car. The plunger on the microswitch will be located so that it is in contact with the guide when in neutral and not in contact with the guide when in 3rd. I went about figuring this buy first making a simple mount for the switch that is held in place by the two front studs of the shifter base. Do not attatch switch to mount yet. You now need to hold the switch where the plunger needs to be placed as described already. Shift from N to 3rd a few times to be sur it is right. Now shift to N and make a mark on each side of the plunger, this is your neutral spot. Now move the switch away and shift into 4th. To make this work you will need to remove a small chunk of the plastic from the guide to the rear of your neutral spot. This is done so that when you shift into 4th position the plunger will pop back out and not remain depressed. Once you have this done you can affix the switch to the mount. Shift to N and push the switch against the guide to depress the plunger. Microswitches make very audible clicks when depressed so you will know when you have it depressed. Secure the switch and shift through gears again to ensure proper function. You may need to round off the corners on the guide that come into contact with the plunger to ensure smooth operation.

Here are some general pics of it to give you an idea-

The red nub in the yellow box is the plunger-


Neutral Position-notice the amount of the plunger you can see as it is depressed-

3rd Gear Position-notice the absence of the guide and the amount of plunger visible-

4th Gear Position-notice the chunk removed from the guide to allow the plunger to extend-
(Sorry for the poor close ups, never figured out how to do those yet.)

Wiring the switch is simple. The switch is has three prongs that are tagged with COM(common), NO(normally open), and NC(normally closed). We will use the Com and NO prongs. NO means that when the plunger is in it's normally extended position, the circuit path throught the switch is normally open, not allowing voltage to flow through. As I am not sure if all the wiring colors are the same for all Celicas clutch safety switches, it will be up to you to figure out which wire is sending the signal (the hot wire) and which one recieves it. Once you have this figured out just extend the wires to reach the switch. The hot wire will plug into the COM prong and the other will go to the NO prong.

The point of this is so that I can safely use my remote starter on my car without fear of it starting in gear. This setup will also allow you to start the car without pushing in the clutch.

04-14-2007, 08:53 PM
Great job on this! The pics aren't that bad, they clearly convey the idea.