Hi folks - This looks like the definitive forum for Ford Rangers and Mazda B-series trucks.

I just bought a 1996 B3000 6 cylinder 3.0L, 2WD, auto trans. Nothing special, but in decent shape for the price. 122K miles (except odo not working)

One problem I'm kind of stuck by.... Speedo is not working. Neither is the odometer. All the other gauges work fine.

I pulled the speed sensor on the trans hoping it was either the sensor or the gears. The plastic gear looks fine and so does the gear it engages in the transmission shaft - at least what I could see.

Hooked the speed sensor (two terminals) up to a volt meter and it registered about 1 V +/- AC when I spun it by hand. Less when I spun it slower, so I'm thinking that's ok.

One of the forums mentioned that a "40 pin connector" under the driver's seat is subject to corrosion, but all I could find was a 2 wire connector that I assume connects to the seatbelt sensor. Does my 1996 even have this 40-pin plug? Where is it?

Any other ideas? Thanks!!!

 

Welcome to the forum

Connector under the seat was 2000/2001, so not a 1996 issue

Sensor seems to be OK

And you don't mention CEL(check engine light) being on, does CEL work?
It comes on with key on, then goes off when engine is turning
Computer is also connected to VSS sensor and will set Code P0500(no speed signal) and turn on the CEL if sensor was bad or its wire to the computer

So probably a "local" issue, for the instrument cluster
Check Cab fuses, 11 and 25, 7.5amp, I mean pull them out and test it or swap it

1995 to 2003 speedometer is electric has its own motor in the cluster, Odometer is also electric and has its own motor, so could just be a blown fuse
Unlikely that BOTH electric motors would fail at the same time

Or a bad wire from VSS(speed sensor) to Cluster, speedo/odo SHARE that one VSS wire

There are two wires on the VSS the Pink/orange wire is a GROUND, you can test that at the sensor
The Grey/black wire is the signal wire, and it has a few Splices on its way to the Cluster because its also shared with GEM module, Cruise module and Computer


As you know the VSS generates its own AC Voltage, but the signal is not the voltage, its the AC sine wave pulse, the sensor is Grounded so only the + side of the AC sine wave is used for speed signal
The cluster, computer, GEM and cruise are all grounded as well, so each just needs a connection to the grey/black wire from the VSS sensor to have the speed signal

You will probably need to pull the cluster if the fuses are OK
Then test the grey/black wire for connection to VSS grey/black wire, or do same test as before, hook up volt meter, set to AC to grey/black wire and Ground wire at cluster plug and spin the VSS

Wiring diagram below for cluster

If there is no signal at cluster, and no Code P0500 then you can run a short jumper wire from GEM's grey/black wire(behind radio) to the cluster to get the signal back, test GEM's grey/black wire first of course


Just a heads up, 1996 to 2003 Ranger/Mazda B-series are interchangeable, plug and play, you can even add one with Tachometer if you want, all are wired for it, and use the White face version as well
If you have VSS signal at the cluster then replace the cluster, repairing cluster circuits never works well
Any time a Cluster is out replace the 6 back light bulbs, they are cheap and DO burn out

 

Thanks, RonD! Great info. Haven't had time to investigate all the above - work, and pouring rain - but just want to say THANK YOU for your guidance.

Panel shows both CHECK ENGINE and CHECK GAUGE warning lights before starting. Both go out when engine started. (Never seen "CHECK GAUGE" light before on any vehicle. Hmmm....)

Fuse #25 was missing - no fuse - and I inserted a 5A fuse (supposed to be 7.5, but I don't have one in my kit). Now get a warning for headlights on and the interior, engine bay, and rear bed lights all work again. Nothing has blown that lower amperage fuse yet.

Fuse #11 has a 7.5A fuse in it. It doesn't look blown and tested good with an ohm meter. I sprayed contact cleaner on it and reinserted. Speedo and Odo still not working.

Previous owner already included a used instrument cluster (same unit, both have tach). A bit more mileage on the new cluster. Haven't swapped in yet. You suggested a few more tests that I'll try before swapping.

May go ahead and install a new trans sensor since that's cheap. Do you know if the ECU is counting pulses (digital signal), or is the sensor generating a voltage increasing with speed (analog signal)? The sensor is only $20, but the problem may just be in the wiring from the tranny to the ECU, as you suggested checking).

Thanks again!

 

1995 and up all used analog signal as the basis for speed signal, 1994 and earlier used speedo cable, mechanical speed signal, lol

Ford used a Variable Reluctance(VR) sensor that generates its own AC voltage, but the voltage is not what is used, AC voltage is a Sine Wave that swings from + to - over time, the Sine Wave is the pulse used for speed, but only the + half of the wave is used as the sensor is grounded

In 1996 the VSS sensor on trans, or transfer case, is connected directly to Speedometer/odometer in the cluster, no computer involved
But computer also gets the same signal, as does Cruise Control and GEM module, so signal is shared

In 2001 to 2003 Rangers Ford changed to OSS(output shaft speed) sensor on transmission, same VR sensor but ran directly to computer, computer then calibrated speed for tires size and axle ratio and sent that analog signal out to cluster, cruise and GEM

In 2004 to 2006 Rangers got a Digital Cluster but still used analog speed signal from computer
In 2007 and up Rangers used digital speed signal from computer

 

Replaced the instrument cluster and now have working speedo and odometers. Yay!

However, side gauges (fuel, water temp, battery voltage and oil pressure) all appear to be reading weird if they're responding at all. Think I'm going to swap the gauges off my original cluster and see if that helps.

 

First check that you have full 12volts(Battery Volts) with key on, at the clusters 12volt pins
Also check that you have 0 ohms to cab ground on the clusters Ground pins

Test battery with Key on/engine off, should be 12.3v to 12.8volts depending on the age of the battery, this will be "battery volts" for your testing

Each of the 3 fuses(ignore fuse 33 wiring) should have this same voltage so each wire on the cluster should have that same voltage

Instead of OHM test you can test voltage but use the cluster Ground wire instead of cab ground, should see EXACTLY the same voltage with either

One gauge failing might happen, 4 failing, not gonna happen

 

Thanks again, Ron.

I pulled the instrument cluster and compared the ohm readings for each of the gauges on the two clusters. All compared well except the water temp and oil temp gauges, so I swapped in each of the two side gauge clusters from the old unit into the new junkyard unit and now they all appear to be working.

Thanks again.

 

this is an amazing thread...been searching for this exact info about 2 days now...kudos RF