need help with my speedometer

[David Anderson]

Bummer,  It just quit.  I have Dixon speedometer with a 4 wire setup.  12+ 12v- and 2 signal wires. 

I checked for 12 volts, it has it.

The 2 signal wires split from the loom and head down through the steering column.  I haven't searched any farther down.

Can this be bench checked?
Where is the sender? 
Several like kind available on Ebay if I just want to plug and go, but I'd like to know if its the speedometer itself or the signal from below.

I called Ametek/dixon.  The guy was 20 years old and couldn't even recognize the thing.  I asked for someone with grey hair, but nobody in the place was that old that might help.  Everything is digital now. 

Any help would be appreciated
David

[thomasinnv]

I'm not an Eagle guy but I believe the sensor is on the front left wheel like many other brands of busses. It works off of magnets on the inner edge of the brake drum.

[luvrbus]

The pulse generator is on the transmission on all the Houston Metro Eagle I been around

[David Anderson]

The pulse generator is on the transmission on all the Houston Metro Eagle I been around

I believe you are correct.  I traced the wires under the dash to the spare tire compartment back into the tunnel,  found the pair under the bathroom and found a pair on a sensor on top of the tranny.  I will ohm the wires out tomorrow. 

If the sender is bad I think I'm sunk.  No way to find a compatible unit on this old speedometer. 

David

[freds]

I believe you are correct.  I traced the wires under the dash to the spare tire compartment back into the tunnel,  found the pair under the bathroom and found a pair on a sensor on top of the tranny.  I will ohm the wires out tomorrow. 

If the sender is bad I think I'm sunk.  No way to find a compatible unit on this old speedometer. 

David

Actually I don't think that is case for the sensor/sender. The speedometer is based on sending pulses on the two signal wires. Guessing but probably alternating AC current.

The power wire was missing as the result of a partial dash conversion on my bus and the behavior with missing power was that while driving along the needle would bounce up to about the right speed every ten seconds. 

Various replacement speedometers need to be programmed for the number of pulses per wheel revolution. I would say hook a volt meter in AC mode and drive the bus to see if the signal is making it through to the front. Or maybe remove the sender and rotate it with a drill.

[luvrbus]

I believe you are correct.  I traced the wires under the dash to the spare tire compartment back into the tunnel,  found the pair under the bathroom and found a pair on a sensor on top of the tranny.  I will ohm the wires out tomorrow. 

If the sender is bad I think I'm sunk.  No way to find a compatible unit on this old speedometer. 

David

Precision Speed in Phoenix should have what you need 602-973-1055 that guy had everything for Dixson

[David Anderson]

Thanks Clifford,

I got in touch with Aaron from Precision and sent him pictures of my speedometer and sender on top of the transmission.  He prepped me as to how to diagnose these components.  I carefully unscrewed the sender and took it to the bench.  It has a square key in it that I chucked onto my drill.  I attached my ohm meter and set it to AC voltage.  I spun it with the drill and it measured 2 to 7 volts AC.  It worked. 

I then hooked the speedometer to a 12v battery, jumped the 2 sender wires to the speedo and spun it.  It all worked.

I took the sender and plugged it into the connector near my tranny, hooked my meter to the sender wires at the dash, had my wife sit in the pilot chair while I went under the coach to spin it and it worked

Ok, what's up?  Aaron said check the ratio box mounted to the tranny.  Hmm. got to spin the tranny to see if the pencil gear turns.  Well, I jacked up one set of drive wheels, aired up the bus, chocked it and released the brakes, spun the wheels, and the ratio box turned the pencil gear.   

Ok, now what?  I put the speedometer back in the dash, the sender generator back on the ratio box, plugged everything together and started the engine.  I held the service brake put it in drive and slowly released the brake.  The speedometer slowly raised to 5mph and I pushed the brake.  It all worked.   

Self healing I guess.  Perhaps after removal, cleaning, and reassembly it all was good.  At least now I know how all this works, and Aaron told me that they can repair most of these old Dixson proprietary speedometers, and they have the sender/generators, and he said they can repair most of the ratio boxes.   That is good to know. 

I want to attach a picture of the sender/generator mounted to the ratio drive on my tranny just for the archive.  I didn't even know what this thing was until yesterday. 

Another thing about my speedometer--according to Aaron it may have been proprietary to Eagle, 1980's vintage, and possible OEM original to my coach which means I may only have 256k miles on my bus.  That seems really low, but it makes me feel sorta good that I might actually have such a low mileage coach. 

http://www.precisionspeed.com/

Dixson model number system
http://www.precisionspeed.com/products/speedometers/

sender/generator for these legacy speedometers
http://www.precisionspeed.com/products/sender-generators/

[luvrbus]

I haven't dealt with Arron since John sold it to him but sounds like he is carrying on the same as John did for 25 years. John taught me how to make a VDO gauge read accurate with wrapping a wire around a pencil to get the right resistance   he was good on VDO gauges just tell him if it was in a Eagle and bingo you had the right sender on the way
 

[freds]

Great to hear that you have fixed it, or at least gave it a sever scolding so it got its act back together LOL!

Just needed to be tapped lightly about the head and shoulders I guess....