Easy Way to Bypass Theft Deterrent System
 

Wife's '90 turbo Supra stranded her in a Home Depot parking lot. Wouldn't crank. Told her via phone to try locking/unlocking doors. No help. Told her to find and pull the "DOME" fuse from underhood fuse block, still no help.

I drive over, try everything I can think of including disconnecting battery for a while, no help. Left battery disconnected. Had car towed to local Toyota dealer--dropped off after they closed.

Next day Toyota mechanic hooks battery up, car fires right up. No charge, got free car wash too. But that is the LAST time this car is gonna pull that stunt. I don't need that complicated factory system-I have my own "jumper plug" that gets pulled out when the car is parked, and it won't start w/o the plug in place.

I've spend 2 days reading a lot of posts here on the TDS. If I simply jumper the wires together for the hood latch switch while the TDS is off, will that work as per a post from years ago? That is supposed to prevent the TDS from arming itself. Do I need to do anything more?

AFAIK, it works fine... and no, it wouldn't have changed unless Toyota techs have gotten very guerrilla in their methodology. ;) I've never tried it though, I have an aftermarket system which controls it... but it's easy enough to test.

Double check the diagram to be sure as to whether you jumper the two wires or sever them.

I cut the hood switch connector off and twisted the wires together. We'll see how that works. I can't tell by looking at the wiring diagrams if they're supposed to be twisted or separated in order to fool the computer into thinking the hood is always open and preventing it from arming the alarm.

The "security check" light never comes on--except when the key is first turned on, so the light bulb is good. But we have always locked the car using the inside door lock buttons--never from the outside key.

Tried twisting the hood switch together, worked OK for a week or so, then wife got stranded at a Costco. Took my 1-ton truck over, tried all the usual tricks-lock unlock everything many times, key on-off twice/three times--nothing worked. Disconnected battery for 30 min., no help.

Toyota dealer was only a few blocks away, so towed car over. Just as the service guy was about to start writing, told wife to try it one more time. Car fired right up!

I'm PMing you the details now.

Thanks. Turns out I *think* the problem is the automatic trans. neutral starting switch!

That'd do it.

You know, if i'd thought it was an auto we were talking about thats the first thing i wouldve said as mine needs the selector wobbling a bit sometimes before itll crank!

I was wrong--not the neutral switch. Believe it or not, wife got stranded again today! I'm lucky I got dinner tonight. Car has been starting fine ~8 times, then nothing. She tried shifting in and out of Park a few times, tried neutral, nothing.

Drive ~10 miles to tow her again, tell her to try it one more time. Car fires right up. This is with the hood switch wires twisted together, which is SUPPOSED to prevent the alarm from arming.

If it isn't the alarm computer, maybe it's the starter relay that's in the pass. side "kick panel". I took a look and it doesn't appear to be easy to get that panel off. I assume the kick panel is on the side at the floor, or is it the underside of the dash?

One thing's for sure, she won't drive this thing until I (we) solve it for good.

Ahh just gets stranger. But if the car always seems to start after towing (hence movement) i'd be inclined to wonder about a loose connection, possibly at the starter signal wire (the small spade terminal) since repeated tries usually coax a dodgy relay into working, just jumps out as funny it never tries till just after towing...

Update:

The last time she got stranded she had NOT locked the car--it was just a gas up stop. So, realizing the car had never acted this way before I changed the starter, plus all the alarm stuff AND your good comment, I figure it had to be a loose connection of the small 12 volt connector for the solenoid on the starter.

Jacked it up and pulled the brown plastic connector out, cleaned the inside, closed the metal opening of the connector down a little with a small screwdriver, and reconnected it. So far so good. We shall see.

Let's hope this gets the beggar, bet these phone calls are getting rather old now! That's all else I can think it would be really, a loose connection somewhere. I suppose if this doesn't cure it it might be worth trying the connections to the trans. lockout switch too.

EDIT-: I didn't know you'd changed the starter, was it completely dead for you to change it? One more possibility is the new solenoid could be faulty though I'd doubt it, you could prove it out if it does this trick again by putting a test lamp on the signal wire that you tightened & earth. If it lights when you try to start but still no go then it's gotta be the starter, hopefully though (everything crossed this end!) cleaning & tightening this spade gets it...

Ran a new 12 ga. wire thru an inline fuse right off the battery, then to a small $5 Autozone relay on the left side under the hood. Ran it down and soldered it to the brown solenoid wire. Then hooked up a small pushbutton switch inside the car to the relay's coil.

Told wife if it failed to crank to leave the key on and hit the button. THEN if it didn't crank it was the solenoid or wire connector. Told her to wiggle the new wire and try again before she called me.

Today she stopped on the way home for 10 min., didn't lock the car. NO crank. Hit the button and drove home! This is the nuttiest problem I've had for a long time.

Sounds like that darn theft deterrent system is still giving you problems. I had a similar experience in my car as well. I disconnected the theft deterrent computer completely, cut and grounded one of the wires on the TDC harness as shown in this post:

http://www.toyota-supra.info/forums/...rm-system.html

Hard as hell to get at, but no problems since then. :D I hope this is helpful

EDIT: I followed the instructions in burton51m's post

Turns out the problem isn't the theft computer, it's the starter relay that's under the pass. side interior kick panel. It works fine when the car interior is cool, say under ~80-85 F. Above that all it does is click.

I need to find a new or good used one, for a car with an automatic trans.

Problems
 

Always a challenge when a gremlin gets in your car. Could be as simple as bad connection to the battery terminals, though not likely I am sure you already checked that.

I have wired a $5 AutoZone relay in parallel with it (separate switch), and that one works every time.

The stock silver relay box says "ECT" near the top.