Well guys I haven't posted here in a while, though I have been lurking in the shadows. The wealth of information on this site is incredible!
But back to the point if this post.
So yesterday I pull out of my driveway to do some running around. At first everything seems normal. It's -35c outside and the heater hasn't warmed the truck up yet(1990 4runner). Then the heater quits, completely!! Damn it!
So I'm driving around freezing my balls off so bad that I neglected to pay attention to anything else happening with the truck.
So I get to my destination, do my thing, and come back to the truck to head home.
Damn thing won't come out of park! Damn it!
So I check the obvious fuses and check to see if the break light work.... Check, all good....?? What the hell?!
So I use the "shift lock override" and get it into gear and get'er home.
Ofcourse, came onto yotatech to see what if anything that you fine people had said about such an issue.
And oddly (very oddly) enough, there was nothing that REALLY addressed my problem!(first for everything I suppose.) so I pull the glove box out to check the fuses for my heater (priority when it's this cold!!) absolutely everything checked out.....
So just now I get a call from a friend stuck in the snow and needed a tug. Load into my ice cube of a truck, and head across town. On the way I realize that all my gauges other than my speedo and fuel gauge are not working.
Pull over and pull the "guage fuse" in the driver side kick panel and replace it with another 10 amp fuse.
Simple enough. Turn the truck on and bang! Gauges work, heater starts blasting, and to top it all off it shifts into gear with out the override!! Yay!
So I guess that if the ecu isn't receiving anything from the tach, it assumes that the engine is still off and won't let you select a gear?(correct me if I'm wrong)

So I guess the moral of the story is to check ALL your fuses no matter how unlikely BEFORE you rip half your truck apart in -35c weather and freeze your ass off!!

Anyway, I hope this helps someone out somewhere down the road!!

Cheers all, thanx for reading, and thanx for all your help in the past.

Regards, M@B

 

The shiftlock is also controlled by the brake peddle.

 

I have had where my gauges did not work and it kept blowing the fuse. It was Eng or Ign fuse ( don't remember which one). Turned out the problem was the Reverse Light switch on tranny had rubbed a bare spot in the wire.

 

That was one of the first things that I checked. Was if the break lights were working. But don't ask me why my heater blower/ac was on that fuse? I have yet to find anything that says anything about the HVAC system being on the "guage" fuse? But it was, so that worked out for me!

 

Nice, you don't want to be fooling around in that weather. I'm up the highway from you in Beaumont, enjoying the lovely weather too.

 

The heater relay is powered through the gauge fuse, as is the shift lock system. http://personal.utulsa.edu/~nathan-b...55shiftloc.pdf

You still haven't found out why that fuse blew. Until you do, you might want to carry a box of 10amp fuses; don't use too many of them.

 

You said 1990 4Runner.. If it's the 3.0, it does have a spark verification signal to the ECU. So, if your gauges don't work the ECU still gets spark verification and you would think it is programmed to assume that the engine is turning.

However, i'm glad I read your shpeal... I'm getting to know the 4Runner's electrical system all to well lately. lol

 

No, it doesn't have anything to do with that; it's much simpler. The shift-lock requires power to release; when you blew the gauge fuse the shift-lock can't unlock. It doesn't monitor rpms; just brake pedal. (You can shift with the engine off; fortunately, the P-N switch then prevents you from spinning the starter unless the transmission is in P or N.)