First thing that comes to mind is check the dash ground, and make sure the cluster is plugged in (those round pins get lightly corroded from sitting). Everything you describe indicates a dash ground issue...
All of my 727 transmissions have a ratio adapter...And last thing to add. I found this picture of apparently what it’s supposed to look like all connected. My VSS seems to be connected straight into the transmission without this ratio adapter part. Is the ratio adapter something that only goes on manual trans or something? Mine is the 3 speed auto. View attachment 975362
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.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
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?
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.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?
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!
That is correct, the 1st gen soley uses the VSS for speed. The ABS sensor is only used for ABS.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
I found a set of ODO gears on Amazon for $15...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