Robinhood150

My speedometer went out a couple days ago and the check engine light came on. The tranny wouldn't shift out of 1st and I moved the shifter through all the gears but it still wouldn't shift past 1st when I drove. So I turned off the engine and started it back up and the tranny started to work again.

After searching here and 4x4wire I suspected it was the speed sensor so I checked the codes and got 73, 77 and 79. Then I checked the sensor according to chiltons and the '95 service manual (I have a 93). I measured the resistance between the terminals and it came out 612 ohm out of an acceptable range of 580-700ohms. There was no continuity from the terminals to the sensor body, and that's the way it should be. From that test is seems the sensor is ok.

Code 73 says, "Low output voltage signal from speed sensor. Check rear speed sensor and differential ring gear"

Code 77 says, "Abnormal signal from speed sensor. Check differential ring gear"

Code 79 says, "Sticking of deceleration sensor pendulum."

Could the sensor still be bad, even though the electrical test showed it's within specs? When I did the electrical test the speedo was working ok. I can't imagine the ring gear is bad, I just changed the gear fluid last year and it looked fine and it's full now.

How about the deceleration sensor, I've never heard of it. Could it be out?

thanks,
Steve

Shoorty911

I had the speed sensor on the tranny go out last year......the speedometer would work occasionally and after it would go off for about 10 sec the "O/D OFF" light would blink until the speedo starting working again.....i had it checked out and replaced the speed sensor and fixed it....

shoorty911

Robinhood150

You know, some people have posted about a sensor or cable attached to the tranny, but I can't find much about it. The trouble codes point to the rear diff and there is no mention of a tranny sensor/cable except briefly in the tranny overhaul section.

Thanks.

Shoorty911

The only speed sensors on the rear differential is for the rear abs (to detect wheel lockup)....the speedsensor that the speedometor uses is bolted on to the passenger side of the tranny....near the back of it right before it "changes" into the transfer case (if i remember correctly)......i think it only has one bolt holding it on the side of the tranny....whatever you do dont take it to the dealer to get it replaced...they will charge you about 270 something dollars just for the sensor and charge extra for labor....and all it is just a "unbolt, pull out, put in and bolt on...may take 5 min at the most....you can get one from autozone for like 70 bucks...

Shoorty

Robinhood150

Hey Shoorty, would you mind taking a picture of it, or I can go take a picture of what I think it is? I took a quick look this morning and saw what I thought to be a sensor (it had wires coming out) at the driveshaft output on the tranny (transfercase?). I'll go take a better look when I get home.

Robinhood150

Ok, I've looked under the transmission and found 2 things that look like sensors, they're both on the transfer case. Should I be looking for a sensor or a cable? Chiltons eludes to a cable, but there's not pictures. Here's the sensors I found:
I think this one is it, but I'm not sure.



Anybody?

its2slo

whats up with the speedometer cable? you already checked it i guess?

its2slo

i think thats the speedo cable in the second pic

Gadget

I do not know the second gens at all, but from the looks of it the VSS is in the first pic and the one in the second pic looks like a posistion switch for 4x4 engagment or a temp sensor.

The oil soaking of the VSS maybe the problem. Oil, pure oil is an insulator, but oil from a gear box or an engine is a conductor due to the metal contaminates. Oil is a good penitrator and it will work its way into things they you would not normally expect.

Another thing that can happen if it is the magnetic pickup or induction type sensor as opposed to a gear driven one is metal filings can collect on the end and mask the signal. Sometimes all you need to do it remove it and wipe the metal filings off of the end of it. I do not know what kind yours is.

Remember codes do not tell you want is wrong, only tell you what diagnostic proceedure to preform to find the problem. If your problem presists look up each of those codes in the diagnostic section of the factory shop manual and follow each proceedure from start to finish without skipping any steps until you locate the problem.

Most of the modern ECUs are fault protected. If a short occures in a sensor circuit the ECU will engage fault protection in that circut to protect the ECU. If a short occured in the VSS circuit and the ECU engaged fault protection in that circuit you will loose all functions that circuit provides like speedometer, tranny shift points and so on. The fault protection will usually reset on a restart and if the short does not reoccur normal operation will be back. From your description, it seems that is what has happed. You may have had an intermitant short in that circuit that cleared on the restart.

This can be from anything like a broked and shorted wire in the harness to a problem with the ECU its self. You will note that on most of the diagnostic proceedures if no other problem is found the last step is usually "replace ECU".

As a start I would remove the VSS and clean it and the connectors and as far up the wire harness as you can get.

Gadget

www.GadgetOnline.com

Robinhood150

No, the second picture isn't the speedo cable because it as electrical wires coming out of it. But that brings up the other thing, I don't even know where the speedo cable is or whether I even have one.

Gadget, what does VSS stand for?

its2slo

its right in that area plugged into the transfer case on the right side of the car, it resermbles that a lot.

its2slo

here it is on my taco, i did it just for you. ive worked on a 91 4x4 pick up's and it looked more like pic#2 that you posted. unless there's something special about runners....

TDiddy

I think VSS = vehicle speed sensor.

Gadget

The newer trucks use electric signal generators and not mechanical cables anymore.

Gadget

www.GadgetOnline.com

its2slo

gadget,
my taco is a 95.5. maybe someday ill get to drive a newer truck on a cold morning, that would be cool to drive a toyota truck and not hear the speedo cable screaming at me on a cold morning!!

Robinhood150

Ok, I think I fixed it. I'll drive it around for the rest of the week to make sure.

On friday I was all set to take it into the dealer and have them fix it, but I received a sign from God not do that. I called 1 dealer and he said the service guys were on strike and wouldn't be back to work for at least a week. I called an independant place and they were booked for a week. Then I called another dealer and they put me on hold and never picked up. So I decided that meant I should try to fix it myself.

I went down to the dealer and asked the parts guy, the service manager and a mechanic and nobody could tell me for sure where the VSS was. The mechanic said there's only 1 person there who knew about the older trucks and he wasn't there. He did tell me it's on the transfer case though. So I went back to the parts guy and he brought the part out and what do you know, it looks just like the part in the first picture. I wanted to be done with this problem so I bought it for the price of $233 including tax (PN 83181-35051).

Installation was a snap, just 1 bolt and unplug the wires. BTW, it's a geared electrical sensor, that is, there is a gear that turns and outputs an electical signal to the speedo. I test drove it for about 15 miles and nothing went wrong.

So I'm crossing my fingers and hoping that fixed it, I've got a wheeling trip this weekend.

Thanks everybody.

Robinhood150

Thanks Jake for going out there and taking that picture.

Dan_in_WI

My speedometer is acting up.

I found these posts. I am hoping somebody figured out what is going wrong with the speed sensors. Is there debris in a mechanism? Is the plastic gear failing? Electical connector?

I would rather fix it than replace it.

Does anybody have the toyota part number or estimated dealer cost?

Also the posts eluded to two speed sensors 1 for the speedometer and one for ??? can somebody clarify?

Dan_in_WI

After Northridge quoted $160 for the VSS I took mine apart. It was only a clip to remove the gear and shaft and 3 screws to separate the body. It is pretty simple to do. Any way I wiped off the insides and cleaned the gear teeth and it seams to be working fine. I did not wipe the shaft off so it would still have lube when it started back up.

The gear is plastic and the shaft has about a 4rms finish on it with a spiral groove around the surface. I assumed the groove was for lube path. I figure some crap got in it and got to the disk the sensor picks up.

This took all of 15 minutes so I would recommend trying it before shelling out the money.

Anybody else ever try this?

Dan_in_WI

Its been a couple of weeks and all is still good.