Speed Sensor / Crank Sensor Newbie info

[gv280z]

If you have had experience with either of these quirky sensors before and know what they are, where they are and what they do, then you can stop reading now.

 

 

I wanted to relate my personal experience with these items even though I'm pretty sure they've been covered countless times before. My truck broke and I did try to research and find answers on here, I didn't come up with too much to go on, so I guess that's why I wanted to just kind of do a reset on a little bit of information.

 

 

So over the years of owning my truck, occasionally it wouldn't want to shift from 1st to 2nd (autotragic) and my wife would say "HEY! Why does it sound like that?!? Hmmmm????" And then it would eventually shift and drive normally. But then while going down the road, sometimes the transmission would start frantically trying to figure out what gear it was supposed to be in and the speedometer was totally off, not even in the ball park....

 

Plus, on an unrelated note, most times when I'd start the truck up, like a minute or two after the engine has been running, the tachometer would start flipping around crazy like, I had no idea why, and this was after tune up and alternator replace, ok so there's that...let's move on.

 

Fast forward about two years, driving along and then suddenly the speedometer hits the deck completely, down to 0.0 and the transmission kicks down out of 4th or 3rd, overdrive or whatever...so ofcourse I pull over to the shoulder, flashers on and do the whole turn off the engine, start it back up again and drive, oh now the check engine light is on....ok, now it's not shifting into 2nd AT ALL, no matter what, unlike before if I just gave it a second, it would shift....uh uhh...not now. 1st is all I'm getting and I'm committed, no offramp, no exit, no where to run to, so I limp over a huge bridge in first gear, go somewhere safe, waste the entire rest of my day waiting on a wrecker to take me home.

 

 

Okay, I get home and start reading and trying to learn. Someone has posted a autotragic diagnostic sequence to count the flashes and find out what's wrong with your transmission. Mine came out to 8 flashes on the led light on the power shift switch which led me to the code Engine speed circuit, which translates to the

 

Crankshaft position sensor which is located under the distributor rotor, under the gold cap, it's the thing that "reads" the little disk with all the holes in it. Ok. So I replace this sensor for $135 thinking this is going to fix my truck.

 

WRONG.

 

It didn't fix the TRANSMISSION.......ahh, but it DID fix something else that I didn't even mean to fix, but once I realized it..I let it ride. The Crank sensor translates directly to the tachometer and probably some other really important ignition timing type stuff as well. So now my tach doesn't bounce around anymore.

 

So, back to the drawing board. I come online and find anything I can on the VSS vehicle speed sensor and finally I'm able to learn definitively the location of the VSS on 4WD Pathfinders, is located in the transfer case on the passenger side, almost directly above the cross member support, and is just held in by a tiny little 10MM bolt. Honestly the hardest thing about this is crawling under the vehicle, and then getting that damn connector to let go. I spent more time on that stupid plastic connector than I did actually fixing the truck.

 

That was one thing that had always stumped me everytime I looked, I was looking in the wrong place, it's not in the transmission, on 4wd the speed info comes from the TRANSFER CASE

 

 

The OTHER thing that always gigged me everytime I tried to look into buying a speed sensor is it's God awful confusing trying to figure out which one to get:

 

http://www.oreillyauto.com/site/c/search/Vehicle+Speed+Sensor/01879/C0033.oap?year=1994&make=Nissan&model=Pathfinder&vi=1211971

 

Look at this link for O'reilly auto parts, they show like several different speed sensors! Some have with manual transmission, some are for automatic trans but 2wheel drive only...uh huh, then there are without 31" tires, and then with 31" tires and automatic transmission...but...it doesn't say 4 wheel drive? Oh wait there is one with 4 wheel drive but NO MENTION OF TIRES!!!!!!!!! Arrrrggghhhh!!!!!!!!! And they all look different, some are short, some are long what the hell is going on here?

 

This is very off putting! Here is what I did. After pulling mine out of the transfer and saw the giant blue pinion gear I realized that I needed the longer style armature, like this one here : http://www.oreillyauto.com/site/c/detail/IDI0/130122/01879.oap?year=1994&make=Nissan&model=Pathfinder&vi=1211971&ck=Search_speed+sensor_01879_1211971_524&keyword=speed+sensor&pt=01879&ppt=C0033 this is the 4WD speed sensor designed to ride in the transfer case, I'm guess the short armature goes directly in the transmission itself on 2WD

 

However, I didn't pay $115 for mine, I got mine for $38 shipped off ebay at this store: http://www.ebay.com/itm/130978267624?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

Okay so they've gone up on then a couple bucks but it still beats paying $100 for it. This arrived today, I removed the locking washer from the top of the armature and removed the blue pinion, and put it on the brand new one. I inevitably destroyed the lock washer go I super glued the pinion gear firmly on to the armature and let it dry, popped it back in and hooked up and took it for a spin.

 

The first thing I noticed was the check engine light went off immediately when I started moving down the driveway in reverse, ohhh what a feeling.....and it it drove great. Fixed.

 

Now the last thing I'm waiting on is I called up Rob in Dallas and ordered the 19 tooth WHITE pinion gear so as to correctly match the speedometer to my 31" tires, when it gets here I'll yank it back out and pry / split the blue one off the armature and put the white one on so my speed will hopefully be dead on.

 

So to recap, below I have listed everything that gigged me and held me up and what I learned about that item:

 

 

CRANKSHAFT POSITION SENSOR -- under the distributor rotor -- monitors engine speed for ignition, feeds the TACH

 

VEHICLE SPEED SENSOR 4 Wheel Drive -- passenger side transfer case 10mm bolt -- feeds the speedometer, tells tranny when to shift -- LONG armature

 

31" tires requires the White 19 tooth gear (this is totally optional, no harm no foul here, your speedometer will just read incorrectly)

 

 

Edited April 14, 2015 by gv280z

[gv280z]

I mentioned I called up Rob in Dallas, this is what I meant:

 

http://www.nissanpathfinders.net/forum/topic/18653-genuine-nissan-parts/?p=315059

 

If you have 31" tires or just stepped down from 31" to 235 15s and need to correct your speed, he can get you the right pinion gear you need

[gv280z]

Here is the automatic transmission diagnostic sequence I followed, apparently it only applies to those who have the power option to switch between power and economy / auto:

 

http://www.nissanpathfinders.net/forum/topic/39086-transmission-problems-help/?p=737772

[SpecialWarr]

Here is the automatic transmission diagnostic sequence I followed, apparently it only applies to those who have the power option to switch between power and economy / auto:

 

http://www.nissanpathfinders.net/forum/topic/39086-transmission-problems-help/?p=737772

 

Geez... that's gotta be annoying for everyone else.

[adamzan]

Well all auto pathfinders have it so it should be a non-issue.