Speedometer/odometer malfunction

[tptedge1]

The speedometer/odometer in my '92 W350 worked intermittently and now has ceased working. At one point, a slap to the dash helped. The local dealer has said the unit needs replacing. Any alternative solutions would be greatly appreciated. The od has 155k on it and has just recently taken a snooze.

Nigel

 

[Greenleaf]

Hah! Got you beat! Mine went to 306549. Lots of folks take it apart and replace the parts/pieces themselves. Lots of folks do it... lots of folks.



Another option is a number of repair facilities /round the country.



The simple thing to do it make certain the pick-up is working. It generates the signal to the speed-o head.



There are simple troubleshooting techniques we use. You may want to search for them in this here foum.

 

[DBF]

The speedometer/odometer in my '92 W350 worked intermittently and now has ceased working. At one point, a slap to the dash helped. The local dealer has said the unit needs replacing. Any alternative solutions would be greatly appreciated. The od has 155k on it and has just recently taken a snooze.

Nigel

Is the problem that nothing's working or that the speedometer works correctly but the odometer doesn't?



Regards, DBF

 

[tptedge1]

nothing works!

 

[Greenleaf]

You clearly have issues. Pull the sensor and physically lOOK at the square drive. They like to become round.

 

[tptedge1]

Thanks! I try that first. I will get back to you if that's ok.

 

[ZedMikey]

I have this problem intermittently. I haven't dug into it, yet, though. It is my assumption that since I lose OD (auto transmission) when I lose my speedo/odo that the problem lies with an electrical sending unit.

But, I was under the impression that my auto transmission was not electronically controlled. '92 CTD, btw... Any insight on this?

 

[dpuckett]

O/D engagement is electronically controlled. So, since your O/D goes out when the speedo snoozes, it would lead me to beliveve it is sensor related, or the parts that get the movement to said sensor.



Check your connections and connectors. Make sure the female ends of the truck end of plug are perfectly round. I've had ro "re-round" them a time or two on various trucks.



Check the wiring in general.



Pull the speedo adaptor off the side of the transmission. Make sure the gear is tight on the output shaft and doesnt slip. Also make sure there isnt excessive wear on any of the plastic gears- drive or driven.



If you have a ratio adaptor box, make sure that it turns as it should. they break off inside and stop spinning.



Some thoughts to ponder.



Daniel

 

[Moab4x4]

VSS test

As found on this site, to test the VSS simply put an ohmmeter across the two pins and very slowly turn the input shaft on the VSS or the ratio adapter. The VSS is a magnetic reed switch that closes 6-8 times per revolution. If you see the resistance change between completely open and very low resistance then the VSS is good.

 

[tptedge1]

Is the problem that nothing's working or that the speedometer works correctly but the odometer doesn't?



Regards, DBF

The odometer failed. The speedo is ok.

 

[dpuckett]

Take it apart and check the internal plastic gears. There is a thread on this subject somewhere- not sure if it's here or elsewhere. There is an outfit called Southern Electronics that will sell you updated replacement gears. Aint cheap, but not bad, either. Get both of them while you're at it- if one is broken ,the second one isnt too far behind.



-DP

 

[DBF]

Another place to get them is "Odometer Gears", 757-593-3478, in Newport News, VA.



DBF

 

[CLamb]

Mine functions like a tach, I can rev the motor at a stop and the speedo will go right along with it. Hold the motor at a high idle and the trip odometer will start counting... at a dead stop. The trip and odo both appear to work ok going down the road, however the speedo does not. Has 303Kish on the clock.