Arved,

As you can see in my signature, my truck, which is similar to yours, is a '92. So, this info may or may not help.

I went through a thrash w/ my speed sensor a while ago because my speedo was acting up.

Close perusal of my FSM (the section of the wiring diagram labled "Combination Meter") along with the speed sensor wiring yielded the following info:

The speed sensor indeed has three wires going to it. On my truck, one is black/orange and comes from the gauge fuse, so I'm presuming that it is the hot lead. Another wire is listed in my FSM as being green/blue, but looked like pure green when I inspected it. This one goes to the "speed meter" on the same side the ECU wire enters the "speed meter." I'm guessing that this wire carries the signal. The third wire is green/red, and enters the "speed meter" on the side opposite the side the green/blue wire enters the "speed meter," and looks to be the ground.

I hope this helps!

 

These are the best drawings I have found so far:
1993 Toyota Pickup Service Manual

 

i know for a fact theres a harness under the dash on the drivers side that when disconnected does kill the cluter including speedo ,fuel,temp and engine light. its the plug in the back of the fuse box inside the cab on the drivers side kick panel man.

 

Arved,

As you can see in my signature, my truck, which is similar to yours, is a '92. So, this info may or may not help.

I went through a thrash w/ my speed sensor a while ago because my speedo was acting up.

Close perusal of my FSM (the section of the wiring diagram labled "Combination Meter") along with the speed sensor wiring yielded the following info:

The speed sensor indeed has three wires going to it. On my truck, one is black/orange and comes from the gauge fuse, so I'm presuming that it is the hot lead. Another wire is listed in my FSM as being green/blue, but looked like pure green when I inspected it. This one goes to the "speed meter" on the same side the ECU wire enters the "speed meter." I'm guessing that this wire carries the signal. The third wire is green/red, and enters the "speed meter" on the side opposite the side the green/blue wire enters the "speed meter," and looks to be the ground.

I hope this helps!

That's awsome, Digger. I can check at least the ground and the supply voltage.

My wires are quite greasy, but nothing a healthy dose of WD40 won't clean up. I do remember a black with orange tracer wire under there.

Thanks!

 

i know for a fact theres a harness under the dash on the drivers side that when disconnected does kill the cluter including speedo ,fuel,temp and engine light. its the plug in the back of the fuse box inside the cab on the drivers side kick panel man.

Well, the fuel and temp guages work just fine, as does the brake, seatbelt and check engine lights. So I don't think the problem is with the cluster ("combination guage"). I think the problem is with the wiring to the sensor (at the transmission) rather than to the instrument cluster.

Thanks, though.

 

These are the best drawings I have found so far:
1993 Toyota Pickup Service Manual

That was the first place I looked, actually. It gives a good pin-out of the Instrument Cluster ("Combination Meter"), but you'll notice the troubleshooting instructions don't include an inoperative speedometer?

OK, on closer look, there is a checkout for the sensor:

"2. INSPECT SPEED SENSOR
"Check that there is continuity between terminals A and B four times par (sic) each revolution of the speedometer shaft. If operation is not as specified, replace the speedometer."

However, it's refering to terminals A and B on the combination meter. I need to narrow things down between faulty wiring to the sensor, and a faulty sensor. And, if the sensor or wiring is at fault, replacing the speedometer itself won't fix anything.

And what's up with the hint just above that step:

"HINT: Pointer vibration can be caused by a loose speedometer cable."

The '93 doesn't have a speedometer cable! Must be leftover from the previous manual.

 

However, it's refering to terminals A and B on the combination meter. I need to narrow things down between faulty wiring to the sensor, and a faulty sensor. And, if the sensor or wiring is at fault, replacing the speedometer itself won't fix anything.

step 1..pull plug from sensor, check for 12v at black/green wire. if so...you have power to sensor.
step 2..check for pulsating voltage of green/red wire and ground while one tire is lifted off of ground, while in gear and wheel spinning. if pulse voltage appears you have a good sensor.
step 3.. check for continuity between point A and B on back of instriment cluster shown in 1993 Toyota Pickup Service Manual 01-21-2006 01:16 PMif it doesnt show speedometer is bad...i think???

 

lol!!:lol:

 

you can try this one and see if there is anything useful in it
http://aarc.epnet.com/application/8578/8578.htm

 

you can try this one and see if there is anything useful in it
http://aarc.epnet.com/application/8578/8578.htm

That's the source I used for tracing things out. Best electrical diagrams I've found to date. I traced back the Speedometer (misnamed "Vehicle Speed Sensor" - I have to assume if it's part of the Instrument Cluster housing, inside dotted box with "Malfunction Indicator Lamp," it must be the speedometer) back to the ECU. However, I've accounted for everything else going in to the ECU, and I can't figure out where the ECU is getting it's signal from the Vehicle Speed Sensor (located on the transmission).

At the top of this thread, look at the links I had to Engine Control Drawing 1 and 2.

Besides, the Vehicle Speed Sensor (at the transmission) has three wires comming out of it. I assume this is V+, Ground, and the pulsed signal going to the ECU. The "Vehicle Speed Sensor" on Engine Control Drawing 2 only has 2 wires, the signal it gets from the ECU (4 pulses per revolution of the speedometer sensor, per the FSM) and ground.

Thanks,

 

this seemes to be the most information i have found on the speedometer sensor, information on this is few and far between. I have a 94' toyota pickup with an A43D auto tranny in it. I was wondering if anyone has had problems with the gear in the transmission not making contact with the plastic speed sensor gear? I can pull out the speed sensor from the transmission and spin the gear manually and it will register in the dash that i am spinning it. but when i put it in the transmission, it doesnt make contact with it i guess. Is there any way to adjust the height of the gear? the gear in the transmission looks just fine also. This transmission is a rebuilt one from a company.

 

did you find the problem or still working on it ?
i am having the same problem
i need to find out what color the signal wire is coming from the computer
if anyone knows
Thanks
Yeger

 

I had this problem.
The fault with mine was one of the three posts had broken inside the male plug. With a small drill bit I exposed enough of the remaining post to solder a thin wire on, and then soldered the other end onto the connector.
Fiddly 3hrs, but it got the job done.

 

This is an old thread

I think I should clarify the basic operation of this circuit, since it looks like it might be easy for someone to end up chasing their tail.

The Vehicle speed sensor sends a pulsed signal (12v square wave) to the speedometer. Then the speedometer sends a conditioned pulsed signal(5v square wave) to the ecu.

Hope this helps.

 

I hope someone can help me with this. I have a 1993 Hilux 4x4 V6 and the speedometer does not work for some reason after taking it to the shop to replace the shifter bushing. Does this truck have a mechanical speedometer cable? and diagram where I can find the things that control the speedometer would be appreciated. Thanks

 

I think the 91s still had a mechanical speedo. To be sure just get under your truck and see if there's a cable or wire coming out of the t-case.