Hi all,

I have a 1999 4runner limited automatic 3.4L with the multimode 4wd with the 2-4 switch on the 4wd stick.

For what it’s worth, I live in California.

When I start the truck from cold, there is no blinking and usually all 4wd modes work fine. after 5 to 10 minutes of driving (I haven’t timed it but it’s pretty consistent. Always in the same few blocks when I’m driving to work. It’s usually right about the time when the nine temp meters starts to rise out of cold), the 4WD indicator on the dash starts blinking and at that point the truck appears to be stuck it was in when the blinking started. After 10 or so more minutes the light will usually pop back off and I can switch 4wd modes normally. Sometimes it will come back on, but after that initial blinking period is over, I can sometimes “bump” the car by taking it over some rough terrain or a speed bump and that will often do it. When the light is not blinking, it will occasionally take a bit to get it to switch but stopping and throwing it in reverse for a bit will usually pop it into place (from what I’ve read, this seems fairly common and I’m not too worried about it if I can get the rest fixed)

I’ve also noticed that air conditions seem to affect 4wd functionality. If I’m headed up into the mountains (thin, dry air), it usually works pretty well. If I head down to the coast (moist, foggy air), it’ll usually stay blinking for most of the trip. I live in Sacramento, which is inland from the coast but near sea level. I start noticing better performance in the mountains at maybe 4000 get or so.

I’ve tried pulling and testing the front diff ADD sensor and the two Transfer case 4WD sensors with a DMM and they seem to test ok.

Any guesses as to what might be the cause here? I’d like to get this sorted out before winter, but I’ve heard stories about people getting hit with pretty big bills for this kind of thing in the shop, so if I can do it at home, I’d love to give that a shot.

 

There are several parts to the M/M electronic transfer case and 4wd system. There should be 4 position switches on the transfer case, one on the front diff, and one on the rear if you have the e-locker.

You say you tested your switches with a multi-meter, but it isn't just open and closed that they need to work. If they have any drop in continuity in the range they need cleaned or replaced.

Blinking dash lights means there is an error, usually a position error.

Read this thread:

https://www.yotatech.com/forums/f2/4...er-ltd-131201/

I know it's long, but there is a LOT of good advice, system break downs, pictures, etc. Once you have working switches, I would open up the back of the transfer case actuator and see if there is any corrosion.