Ok so I have had my 99 3rd gen for about 1.5 years or so. About a month ago I noticed once in a while the ABS light would stay on after starting the vehicle, but only when the temp is below 30 or so. With the temp anywhere above 30 degrees or so it never happens, and once I drive about 3-4 miles or so it shuts off and everything is normal until it sits for a while again.

Things I know for a fact that do not work every time this happens are the speedo, rear defrost and the park/brake interlock (I have to use the override button to get it out of park). I have also recently discovered a few other things that do not work until the ABS light shuts off, I am going to have to assume they weren't working other times as well I just hadn't used them so not 100% sure. Windows, door locks, maybe blinkers (not real sure on this one).

I was having an issue with the positive battery terminal coming loose, I was hoping fixing that would fix the problem but no luck.

I am at a complete loss as to what the problem might be. Once I drive for a bit all is well and I have never had it freak out once it all starts working again until I park it for a bit. It's only does it when the vehicle and outside temp is cold. Any ideas would be greatly appreciated.

Sounds like you have a couple separate issues going on. You must have a abs problem though, the combination of 4 of them also provides you with vss/speedometer, you can pull the code and count the flashes or combination of flashes to determine the DTC. Could be a piece of metal or rust on a sensor, especially if you had any bearing work done, rust can also push the sensor out of position, or a bad sensor, wire or connector. This is for 01-02 but it might be the same, maybe someone has the 96-00 version.
http://www.teamtoyota4x4.org/archivi...webdb/dtcc.pdf

I'm thinking the park position lock has something to do with the switch for the brake pedal or switch in the shifter. Rear defrost could just be a rear window position problem or the wires going into the hatch. Maybe a worn out ignition or ignition key could cause a few of these problems though cutting power.

I think they are all related and I do not think it is actually an ABS problem - No ABS code. I think it is some sort of electrical/computer issue. I have not had any rear axle work done. The vehicle basically sat for a couple years undriven before I bought it as it belonged to an older lady who no longer drove.

All of this happens at the same time, every time. Immediately after start (only when cold outside) ABS light stays on, windows do not work, door unlock does not work (lock works), rear defrost button light does not come on etc...

After a few miles of driving, or 10 minutes or so of idling the ABS light goes off and that's how I know everything else will work.

New Info: Yesterday I drove to the store (about 15 miles) and when I came out of the store it acted up like it does when cold, it's the first time it has done that. But shortly after I pulled out onto the highway I heard a click that sounded like it came from under the dash, sounded sort of like a relay clicking. Immediately after the click I saw the speedo spin up to speed, then the ABS light went off and everything was normal again. I usually have the radio on so this is the first time I have heard the click noise.

When you say no ABS code, have you actually jumpered the diagnostic port to check for a code while your ABS light is on? It does sound like your problem is likely with a shared component, but knowing what part of the ABS system is down and causing the light will help with locating which shared component.

As an avid reader of all things 3rd gen, the Only other time I have read about this and abs light with no abs code from the under hood diagnostic jumper is when the ignition cylinder wasn't making a good connection, I can't find the post but I recall he had new dealer supplied keys ordered using the key code and VIN and it seemed to solve his problem surprisingly, I would have thought a new ignition cylinder was needed but all he replaced was the keys. I'm not sure if it had an immobilizer system though or if that would change anything except level of difficulty to replace keys and ignition cylinder.

Check your ecu-ig fuse driver door under dash fuse box.

I jumpered it, now whether the ABS light is on or not is sort of hard to determine. You jumper it with the vehicle off correct? So I guess I would have to start the vehicle, wait for the light to stay on, shut it off and then jumper it? When I jumpered it I just went out and did it without starting it, I guess I assumed it would store the code.

I do have another set of keys for it so I will try those and see if I have the same issue. Never even thought to try that, thanks for the tip!

I will certainly check this first thing in the morning, it will be cold so I will also try my other set of keys at the same time to see if that makes any difference.

Thank you all for the ideas, I have done a lot of reading here since I acquired my 3rd gen and I did a lot of searching for anything like this prior to posting but could not find anything that was like what I am experiencing.

You jumper it in ACC, so electronics on but engine off. I don't believe that it stores the code, so you would need to turn the car on to confirm that the light is on, then turn it off and put it in ACC and jumper it.

By off I meant not running, but I did it one morning without driving the vehicle so the last state it would have been in when shut off is with the ABS light off. I will start it up first to make sure light is on, then shut it off and jumper it and see what I get.

Well of course it has been in the upper 20's this morning and it is acting normal, like I said it only seems to happen when it's pretty cold out....at least for now. I will keep trying it to see if it will throw a code.

All fuses under the drivers side dash area are good. It does have the toyota security deal so I wonder if that is maybe where the issue lies. There is a little black box under the dash that looks to be tied into that little security indicator to the left of the column. I wonder if that is where I hear the clicking from when everything starts to work. The key I have been using is not the official black plastic topped Toyota key, looks to be a key that was made but I have been using it for over a year now without issue and so long as it is warm out it still works without issue. My backup set is the official Toyota key and the reason I don't use it is because the little black plastic part at the top is broken so it will not stay on a key ring.

I can only wait until it starts acting up again to do more diagnosing.

You can get the key cut at the dealer.
courteasy of @ryanbt The master is 90999-00186 the sub is 90999-00188 the master w/plastic is 90999-00185.
Electrical gremlins are hard to diagnose when theyvare intermittent. Cleaning grounds is not going to hurt. Dirty grounds can cause squirrely issues.

Not much to report on the issue.

While checking the fuses I poked around and fiddled with that little black box I found under the dash by the drivers feet (i think it's associated with the Toyota security thing). It then warmed up for a while so the problem disappeared. Now that it is cold again the problem has yet to resurface. My only conclusion is, messing around under the dash must have jostled something that needed jostled.