1990 4runner 3.0 auto 247,xxx miles

Hi, I've searched around a bit to see if I can figure this out. My speedometer takes a little bit of time to 'warm up' or something to start working right. When I cold start, the speedo is extremely sensitive, jumping all the way to the pin with little throttle, and needs to go back and forth between stops and stuff to start working right. Once it is working right, it is fairly accurate when compared to my gps and the 'driving next to a friend' method. It will be off by about 2-3 or so mph at 65, reading low. This does not really bother me much, but it might coincide with my main question.

My odometer reads about 9.3-9.5% low from my gps. My label on my door jam indicates I have the 4.56 gears, no indication of factory tire size, but with the air pressure references 10.5x15 which I assume to mean 31x10.5x15 (which are on there right now) as those came stock on the ones that were not ~28". Based on math, with the circumference of the tires and stuff, the difference one would see between 28 and 31 inch tires would be around 9%.

So I guess my question is, why would my speedo be fairly close but my odometer not so close to being on? Is there a possibility the po swapped the rear diff for 4.10 or something for some reason causing the odo to be low but not really affect the speedometer? Or are the cables and gears in the cluster just going bad causing it to not read right? Either way, not a big deal, just something I'm curious about.

Thanks for any input and gained knowledge!

 

seems like the issue will be in the insturment cluster. I name this the most probable suspect

 

A floppy speedometer reading (reads zero, then jumps up to correct speed, every now and then drops to zero for a few seconds and back up) is a classic sign of a failing VSS1 (speed sensor in the back of the transfer case). When the speedo reads zero, the odometer isn't accumulating, so that could explain a low odometer reading.

If it is the VSS1, when it drops to zero it will "disconnect" the cruise control.

Are those your symptoms?

 

The speedometer doesn't stay at zero then jump, it spins around to the full speed pin with little acceleration. And stays there until I slow down slower than about 20, then the needle will make its way back down to zero once I'm stopped. Then repeats this a few times until it is normal. The odo seems to turn separate from the speedo. My odometer doesn't move at a rate proportional to the speedometer and time.

 

what is the easiest way to find the gear ratio in case my tag wrong or something?

 

Hey guys... Not to invade this thread but im having a hard time locating the answer to my problem..

I put in an SR5 cluster in my '93 Hilux
The tach is adjusted via potentiometer to read rpm correctly
The speedo wouldnt work at first until i drove for about two miles and now it is fine.
I rolled the miles to match my actual mileage using the following link:
https://www.yotatech.com/51334289-post78.html

The odomoter and Trip meter are not moving.. Nor advancing and i cant figure out why.
The VSS has been replaced a while back so its not that.

Any suggestions ?

 

You can jack it up, put it on jack stands, mark your tire so you can see when it makes a revolution and count how many times your driveshaft turns. I won't be exact but pretty close. If your truck does have 4:56, those gears usually came with 31" tires iirc, mine did as well.