[sdeeter19555]

Yes it has 5 volts like it is supposed to. Oh and another thing that doesnt seem to work is windshield wipers. Not sure if thats relevant

Add a stand alone ground wire to the windshield wiper motor...this is a pretty common fix if the motor isn't working. I usually attach the new ground to one of the screws at the end of the motor.

 

[sdeeter19555]

The newer Dodges use the rear wheel speed sensor for the Speedometer but not the 1st and 2nd Gen's.

Have you checked for volts at the VSS wires?

Just to clarify, the 2nd generation trucks use the ABS sensor for speed up through 30mph where the actual speedometer sensor in the trans starts reading.

That's how you can tell which sensor is bad: speedo up to 30 and dead, speedometer sensor; speedometer dead and comes alive at 30mph and up, ABS sensor.

 

[sdeeter19555]

So my last post was about how my speedometer and odometer doesn't work. My brake light and ABS light are both on.

I have since put in a new VSS on the trans. That did not solve my problem. The new VSS came with a new pigtail connector so I looked at the old wires and copper was showing through on multiple spots so i cut em and put the new connector on with wire nuts. (temporary as a test) Still nothing to the speedo or odometer.

I was reading through a older post about how someone had the same exact issues as me and their fix was the ABS speed sensor on the rear axle pumpkin. So I got a new ABS speed sensor and installed it today. Lights are still on and the same problems persist. I went ahead and unplugged the box behind the glove box so I am only dealing with the brake light being on. Who needs ABS anyways.

Next step will be pulling the gauge cluster and looking at the speedo/odo gears which I have been putting off in hopes that there is an easier fix.So are there any other potential avenues to go down with these problems I'm describing before I tear into the dash again?

Have you checked vacuum? The brake light will stay on if there isn't sufficient vacuum for the booster. It will also stay on if the emergency brake pedal is tweaked slightly, I had to bend mine.

I also unplugged my ABS box, the RWAL module on the frame is available from Rock Auto if you want to replace it.

 

[sdeeter19555]

the small white plastic gear set that is replaceable ( if the parts are still available ) are just for the odometer operation. the speedometer itself is run by a small electric motor that is controlled by the signal from the VSS. you do not have to pull the cluster from the dash to remove the speedometer. it pulls out towards the steering wheel when you get enough screws out (four if i remember right). it has to come straight towards you because of the electrical connections. the speedometer can be taken apart. parts of it are very delicate. when i took mine apart, the motor that controls the speedo needle fell apart in my hands. i found a used cluster and swapped parts until i had a working speedometer. you may want to go ahead and pull the cluster and closely inspect everything. the wiring, the connections, the circuit boards etc. if you haven't already done that. you can go ahead and upgrade your dash lights while you are there. i put in LED's. probably not worth taking apart just to do that - mine didn't improve all that much. the factory service manual has some good tips on trouble shooting the gauges and is good for helping to understand how it all works. if your odometer gears have never been replaced they are probably toast - the plastic on the original ones are not very good. make sure you shop around for those gears - some of the prices are outrageous!

There is also a company by the name Mr. Heaterbox that can replace any and all of the gauges in out clusters and replace the ODO gears. He uses a VDO speedo as a replacement. From what i have gathered, they are not cheap but what are your options besides used parts. I plan to send one to him as my speedo is very lazy but the ODO reads perfectly (eliminates the VSS as a problem)...

 

[ViolenceJack]

i dont know if the VSS uses a hot wire or a ground but one wire would be "to" the sensor and the other wire would be "from" the sensor. there are three electrical connections to the speedometer. one is 12v constant with the key on - one is constant ground and the other is the signal wire from the VSS.

i dont know if the VSS uses a hot wire or a ground but one wire would be "to" the sensor and the other wire would be "from" the sensor. there are three electrical connections to the speedometer. one is 12v constant with the key on - one is constant ground and the other is the signal wire from the VSS.

Good info bob thank you! I planned on taking the cluster out anyways because i already bought LEDs to put in it I’ll probably start tearing into it tomorrow. Hopefully i’ll be able to finally diagnose if it’s those gears or something else.

 

[ViolenceJack]

There is also a company by the name Mr. Heaterbox that can replace any and all of the gauges in out clusters and replace the ODO gears. He uses a VDO speedo as a replacement. From what i have gathered, they are not cheap but what are your options besides used parts. I plan to send one to him as my speedo is very lazy but the ODO reads perfectly (eliminates the VSS as a problem)...

Wow thanks for all the info! So i’m sure there is a vacuum leak on the booster. I can hear it when i turn the truck off.

And for clarity sakes, when you say the 2nd gens use the ABS for up to 30 mph and then the VSS after, does that imply that the 1st gen doesn’t use the ABS speed sensor at all for the speedo? I am still a noob at all this diesel mechanic stuff

 

[sdeeter19555]

Wow thanks for all the info! So i’m sure there is a vacuum leak on the booster. I can hear it when i turn the truck off.

And for clarity sakes, when you say the 2nd gens use the ABS for up to 30 mph and then the VSS after, does that imply that the 1st gen doesn’t use the ABS speed sensor at all for the speedo? I am still a noob at all this diesel mechanic stuff

That is correct, the 1st gen soley uses the VSS for speed. The ABS sensor is only used for ABS.

 

[ViolenceJack]

i dont know if the VSS uses a hot wire or a ground but one wire would be "to" the sensor and the other wire would be "from" the sensor. there are three electrical connections to the speedometer. one is 12v constant with the key on - one is constant ground and the other is the signal wire from the VSS.

oh and quick question because i just went and got in it for the first time in the dark. None of the back lights in the cluster work. the oil light works, and high beam indicator works, but nothing else lights up when i have the lights on. Could that potentially be connected? Do the speedo and the back lights run on the same circuit for that 12v supply?

 

[ViolenceJack]

That is correct, the 1st gen soley uses the VSS for speed. The ABS sensor is only used for ABS.

Damn, well it was worth a try. Now i know and maybe future people will see this thread and learn this sacred knowledge.

 

[bob wyre]

you need to take the cluster out and look at everything. the dash lights not working could be anything from burnt out bulbs to your light switch. the speedometer is not on the same circuit as the lights. the gears only operate the odometer. the speedometer is operated by a small electric motor.

 

[ViolenceJack]

you need to take the cluster out and look at everything. the dash lights not working could be anything from burnt out bulbs to your light switch. the speedometer is not on the same circuit as the lights. the gears only operate the odometer. the speedometer is operated by a small electric motor.

gotcha. I’ll be taking it apart tomorrow and i’ll update with my findings!

 

[ViolenceJack]

well gang this don’t look great 😅 @bob wyre @sdeeter19555 @9297oldram

 

[9297oldram]

You found the problem, now just need to find a replacement.

 

[ViolenceJack]

yessir. I wish i had just took this out from the start to inspect it. would have saved me alot of money and time but i learned alot in the process

 

[ViolenceJack]

Hey fellas, do any of you know if the speedo from a 94 dodge dakota is interchangeable? they look the same in a video i just watched and there is one at the pick a part place near me

 

[ViolenceJack]

actually disregard. i got a replacement speedo from a scrapyard today. the gears in it turned to powder when i took it apart. I am gonna go ahead and try to find some cheap ones

 

[cutoutcummins]

Check out ovens garage on YouTube. I believe he did a video on it with some link's to the parts


1990 w250 12v Cummins

 

[ViolenceJack]

Check out ovens garage on YouTube. I believe he did a video on it with some link's to the parts


1990 w250 12v Cummins

Good call. I wonder if there is a 3D print design for these gears anywhere on the internet. That would be pretty neat if i could just print them out

 

[sdeeter19555]

actually disregard. i got a replacement speedo from a scrapyard today. the gears in it turned to powder when i took it apart. I am gonna go ahead and try to find some cheap ones

I found a set of ODO gears on Amazon for $15...

 

[ViolenceJack]

Aight cool