Speedo off like 15 or so MPH and odometer doesn`t work ? 1991.5 W250

[GardnerM]

I have searched and found many answers but nothing definitive in my case. Would me speedo be off if the little gears are broke inside the cluster ? Or would a sending unit from the trans be the prob ? Speedo is off at least 12-15 MPH. I need this to deduct mileage and track DOT miles ....Bought the truck and have been using it but need to address this now . Can you send the cluster off ?? Just have to zero in before I start tearing the cluster apart and have a truck down Would my local dealer be able to correct it ?

 

[cerberusiam]

Short answer, could be both. The gearing of the truck will drive which t-case adapter is used to get the correct output reading for the VSS. If that is geared wrong the actual signal will be incorrect.

The speed sensors are a royal PIA becasue they can be subject to wear and voltage drops also which will affect ttheir output to the PCM to detemrine what the speedo says.

The odometer not working and speedo working is normal, the cluster drive for the odo is likely bad or broke. You should be able to send the cluster to a repair place and have it fixed. Dealer is useless for fixing the cluster, they would send it off.

 

[DVolk]

For DOT miles a person might be able to get a hub meter to work on a pick up possibly . like they use on semis .

 

[GardnerM]

Ill check on price of a hub meter. She starts shifts stops nice (need e brake rebuild) , and all I need is my annual dot inspect and track my miles for taxes. And yes she does qualify for a Dot number because when I hook up a trailer ,gross goes over 10,001lbs I would be right at 18k.

 

[RWherley]

Check your tire size, if some one put taller tires on the truck it would throw the speed o off.

 

[Bob Beauchaine]

What transmission are you running - G360 - NV4500HD or Auto trans? If you could fill out your sig it would help us to help you.

 

[GardnerM]

What transmission are you running - G360 - NV4500HD or Auto trans? If you could fill out your sig it would help us to help you.

Its a stock automatic with OD. My other 91 is a Getrag 5 sp. that I have been scrapping out .Wonder if I could switch out clusters with my older 91 .Speedo worked on it when I parked it

 

[Simplysmn]

Yes they will swap out cluster wise and maybe even put the speedo stuff from the other truck on trans also .