jtrent

It's a factory Toyota key fob, exactly the same as the two fobs I had with my 2000 4Runner (also a Limited model) a few years ago.

I know where the Security LED is and it will be a bear to get far enough into the dash to trace it out. What is the "mic" you're talking about?

lee

finally got my hands on a multimeter and rechecked my fuses. while the ignition fuse on the inside appears visually to be good, it was blown.

replaced it, and it fired right up.

sorry i cant be of help, but i wish you luck man.

jtrent

Thanks Lee.

This morning was the first freeze we've had in well over a week. Tried last night at 38 degrees and the truck turned over just fine. Tried this morning at 31 degrees and no go. Again, the security light continues to flash, despite the key being in the ignition.

Whatever it is is DIRECTLY related to the cold weather and will not malfunction unless it is at or below freezing. What in the hell could this be???

MTL_4runner

Lee and Jeff, you guys have completely different problems. I'm glad yours was a simple one Lee......it could have been alot worse by reversing the poles, but glad it was just a fuse after all. Check all the wiring to be sure you didn't melt any of the wiring as well (ie none of the wires are stuck together).

Jeff, it sounds a bit like a relay malfunctioning somehow, but I don't have a wiring diagram for your truck handy to look at right now. If someone has one for the alarm/immobilizer circuit, post it up and we'll all have a look.

bigacuralvr

sounds like a bad relay possibly. Man, I wish I had the truck in front of me, Im sure I could figure it out.

WT

Yeah at this time I think it maybe a relay getting stuck or being held open/close when its below freezing outside too but hard to say which one it is without a diagram schematic to look at. Some thing to try maybe is leave the lower part off the dash off and you should see some relays under there for the imobilizer circuit or maybe for the ignition cut off ones too, when you put the key in and notice the alarm light still binking try tapping on the relays see if one pops or makes the light go out. Hate to say it but its a process of elimination and it just takes time. I still vote to remove the factory alarm first to be sure its not faulty and keeping the relay latched when its should be off, cause thats what controls the blinking alarm light and also control the relay that would be for the ignition cut off too which maybe whats actually stopping the truck from fireing by killing power to say the fuel pump thus no gas pressure you said you checked for.
Just more ideas I guess..

jtrent

WT: DOH! Put the lower dash all back together today since I had a lot of running around to do and the hood and fuel door releases were getting on my nerves under my feet.

Anyway, I have been racking my brain what could possibly cause this cold-weather-only phenomenon and so far I can only come up with two things:

1) As some of you have suggested, it's a relay sticking.

2) It's a nicked or shorted wire that the cold weather affects resistance or causes the insulation to constrict enough that it shorts or something (BTW I'm sure I just showed my electrical ignorance)

jtrent

Well I've now tried a couple more things and failed miserably at both.

1) Tried leaving a key in the ignition from when it WOULD run until it was cold enough that it was likely to not. Sure enough, the security light was not blinking, so I thought this may work. However, as soon as I turned the key over, the security light began to blink and no start...

2) Tried using a long heavy-duty extension cord and a 1500w hair dryer to heat the key cylinder...also no go. This indicates to me that the cold is not directly affecting the key cylinder or anything in close proximity to it. I also directed the hair dryer under the lower dash for about 15 minutes in the hopes that a relay or something might get up to temp enough to crank the truck, but again got no results.

Stumped again...

jtrent

SON OF A B****!!!

It's 62 degress here and really nice out. Just got back from my in-law's house (about an hour drive) and backed into the driveway. I had only been home for maybe 10 minutes and was about to back the truck up, hook up the jetskis, and take them to my mom's house to store for the winter and free up some garage space here. Got in the truck, insert key, and yep...you guessed it...security light is blinking still.

So now there is no pattern of only happening in cold weather. I am buying another vehicle to drive this weekend. I am going to give this damned truck to Toyota I guess and just tell them to keep it till it's fixed. This SUCKS!

bigacuralvr

Well, just so you know....the security LEDS in the dash is standard on ALL Limiteds with the immobilzer. This LED DOES NOT mean you have the RS3000/3200 alarm. From what you said...you do not have an alarm, you have the factory immobilizer key and keyless entry. My 99 had the same thing, and no alarm, anywhere.
Here is what I would do...go to Toyota, and get the location of the Immobilizer relay. When it does not start, tap on it, and see if that helps. You've got a new key, everything was checked in the fuel department, it really leads to the immobilizer system. I guess what nobody knows, but someone needs to know, is where the immobilizer brain is, and what it consists of. Toyota has to know this info.
Just my .02....
Brett

jtrent

Brett: I agree with you 110%. The only thing that leads me to believe I've got an alarm is that if you lock the doors with the fob with the windows down and reach in and pull up the door lock, a siren goes off. The only way to silence this siren is to hit unlock on the fob. Is it possible this is just part of the keyless system, or do I actually have an alarm?

Also, if I could find a relay associated with the immobilizer system (guess I'll have to spend some time at the dealership pouring over the FSM) I would just replace it. It'd be worth the cost just to find out if this would fix it, since a lot of things point this way...

profuse007

I am not sure what suspected problems you came up, only reply to last post.

You have an alarm. When alarm goes off, it prohibit you from starting(cranking) the car.

the immobilizer is most likely to be built into the ECU, and i am not 100% on that. If you still have problem with bypassing immobilizer at cold weather, check the transponder antenna at the key cylinder. Also try another key if it happens again.

If after all that and it still doesnt work, take it to a mobile security store and have them install a bypass (preferbably DEI 555F, if not better because 555F still have issues with cold weather) .

gl

bigacuralvr

Even if someone was to install a 555f...there wouldn;t be anything to hook the unit into. His problem is the Immobilzer. If it doesn't start with 2 different keys, a 555F isn;t going to fix the problem. I've also never had any issues (Knock on wood) with my 555F, and it's been used at very extreme temps.

Find where the immobilizer circuit is, and go from there...

Brett

profuse007

well, didnt know that he tried both key, and thought that he had trouble during cold weather.

not all ppl will have problem w/ 555f, but ive came across w/ ppl over past several yrs having problem w/ their pellets freezing up on them and they have to reposition their pellet.... thats another story if you know what i am talking about. dont ask me why or how but search on www.the12volt.com
to the thread starter:

check all connection at the key cylinder and ECU b4 taking it to toyota for diagnostic.

jtrent

Well, looks like it's the ECM. Looks like it's going to take about $1500 to find out... =(

MTL_4runner

Get a used one from a junkyard before you go shelling out $1500 for a new one. Dealers love to have you pay to play parts replacement and the ECU is very rarely at fault so play it safe and get a used one first to try out (there should be plenty of 99 ECUs out there to be found).

jtrent

It was the ECM. Had to replace it and all my keys. Dealer cut me a great deal, so it didn't hurt too bad...

I've now been through 25 degree mornings with no issue and a 75 degree weekend to prove out both sides of the spectrum. It's been great so far...

xa0s

Well, I seem to have a problem with this exacty same scenario. I got a 1999 Toyota Tacoma Prerunner. It happens every time when its cold (I live in Vail, Colorado). This is not the first year it has happened. Its been happening at least once a year the last three or four years.

Now, I cant get my truck fired up. I replaced the starter this time, and it still wont fire up. I can feel it cranking. Can this be the ECM too?

xa0s

Never mind. Too thick of an oil is why.

brandyn85

i have had this problem a few times with my 99 runner as well... and have been debating on bypassing the immobilizer system... plus i only have one chipped key and about 5 valet keys that are just about worthless... couldnt someone just replace the 99 ecu with one out of a 96-98 that wasnt equipped with the immobilizer? and it would pretty much be gone???