Seeking advice on next step to fix speedometer

willrek

willrek

Member
Supporting Member
Joined
Mar 11, 2022
Messages
33
Location
El Campo, Texas
My 2002 Sahara has been plagued with the 9mph off speedo since I aquired it in February. Love my Jeep, but really want to get this fixed since I drive it everyday. I have been through the gear change route and tried several before a forum contributer suggested it is probably the age of my speedo and a weak spring causing the error. My delima is how to best proceed with a fix, either try to find a salvage speedo cluster (which may very well fix the problem---but replacing one 20 year old guage with another 20 year old guage has me concerned about the longevity of the fix); or to use a product like the speedohealer. I've looked high and low and it doesn't appear anyone services this particular model of speedometer. Thanks to all who have helped. This forum has been invaluable to me!

Will
 
willrek said:
My 2002 Sahara has been plagued with the 9mph off speedo since I aquired it in February. Love my Jeep, but really want to get this fixed since I drive it everyday. I have been through the gear change route and tried several before a forum contributer suggested it is probably the age of my speedo and a weak spring causing the error. My delima is how to best proceed with a fix, either try to find a salvage speedo cluster (which may very well fix the problem---but replacing one 20 year old guage with another 20 year old guage has me concerned about the longevity of the fix); or to use a product like the speedohealer. I've looked high and low and it doesn't appear anyone services this particular model of speedometer. Thanks to all who have helped. This forum has been invaluable to me!

Will
Click to expand...
The speed signal from the sensor goes to the PCM first, which then positions the speedometer needle accordingly. If you own, or can beg, borrow, or steal some kind of OBDii reader, try to determine what the PCM is reporting for vehicle speed. This could help determine if the problem is with the cluster or not. If the speedometer needle and the PCM indication agree, then the problem is elsewhere
 
  • Like
Reactions: willrek
rouxbicon said:
The speed signal from the sensor goes to the PCM first, which then positions the speedometer needle accordingly. If you own, or can beg, borrow, or steal some kind of OBDii reader, try to determine what the PCM is reporting for vehicle speed. This could help determine if the problem is with the cluster or not. If the speedometer needle and the PCM indication agree, then the problem is elsewhere
Click to expand...
Thank you. I'll try that. I have a small OBD2 reader. Hopefully this will work.
 
willrek said:
(which may very well fix the problem---but replacing one 20 year old guage with another 20 year old guage has me concerned about the longevity of the fix)
Click to expand...
Your problem seems pretty rare. If you do find the OBD reported speed is different from what the gauge is reading I wouldn't worry about a new cluster failing the same way. Unfortunately, swapping instrument clusters is a whole deal with the mileage and all the other computer crap from what I've heard. Did you try the cluster test I suggested in the other thread?
 
  • Like
Reactions: willrek
pagrey said:
Your problem seems pretty rare. If you do find the OBD reported speed is different from what the gauge is reading I wouldn't worry about a new cluster failing the same way. Unfortunately, swapping instrument clusters is a whole deal with the mileage and all the other computer crap from what I've heard. Did you try the cluster test I suggested in the other thread?
Click to expand...
Thank you. Yes I did the cluster test. Everything lit up and/or moved. Wasn't really sure what to look for as some of the guages did not move through the full motion as I thought they should. I'll be doing the OBD speed check tonight...hopefully.
 
willrek said:
My 2002 Sahara has been plagued with the 9mph off speedo since I aquired it in February. Love my Jeep, but really want to get this fixed since I drive it everyday. I have been through the gear change route and tried several before a forum contributer suggested it is probably the age of my speedo and a weak spring causing the error. My delima is how to best proceed with a fix, either try to find a salvage speedo cluster (which may very well fix the problem---but replacing one 20 year old guage with another 20 year old guage has me concerned about the longevity of the fix); or to use a product like the speedohealer. I've looked high and low and it doesn't appear anyone services this particular model of speedometer. Thanks to all who have helped. This forum has been invaluable to me!

Will
Click to expand...
Did the gear change effect the speedometer and is the needle steady and just off? As @rouxbicon suggested I would monitor an OBD tester, gps and cluster to try to verify if just the speedo is off or an input.if you find the cluster to be the problem there are companies that can repair clusters. I would check with a repair company to see if they can repair it.
https://clusterfix.net/store/product/2001-2002-jeep-wrangler-instrument-cluster-repair/https://www.nhspeedometer.com/vehicles
 
  • Like
Reactions: willrek
Thank you for those links! That's awesome! To answer your questions, I initially bought a 33 tooth gear after checking the tables for 31" tires. This made the problem worse. It went from 9mph over to 12 over. (guage reading faster than travelling) So I did calculations using the mathematical formula given (60/51*34)= 40tooth gear. Tried this. Crazy thing with the 40 tooth gear...at lower speeds it was way off, but as speed increased, it got closer and closer to true. So, something aint right. I put the original gear (34) back and am going to check off the OBD reading.
 
There's some small chance you just have bugs or spiderwebs in the cluster screwing it up. You could pull out the cluster and remove the front panel and move the needle around gently blowing it out before you totally replace it or send it out. The test should go 20-55-75 mph if it is working correctly, if you can get it to do that it should be okay. It's worth a try if you can get the cluster out.
 
  • Like
Reactions: willrek
pagrey said:
There's some small chance you just have bugs or spiderwebs in the cluster screwing it up. You could pull out the cluster and remove the front panel and move the needle around gently blowing it out before you totally replace it or send it out. The test should go 20-55-75 mph if it is working correctly, if you can get it to do that it should be okay. It's worth a try if you can get the cluster out.
Click to expand...
Thank you. I'll test again to make certain of the readings.
 
macleanflood said:
Is it possible the gear in the tail shaft of your 231 is hosed? A bore scope might be in order...

-Mac
Click to expand...
I guess anything is possible. But it works consistently and smoothly. Not jumpy. I would think if the gears were gimped, it would jump around. But it's easy enough to get to....just need a bore scope. Thank you for the suggestion
 
Mall'er said:
Are you going off the tag, or did you verify it yourself?

Takes a bit of effort, but you can use this calculator to figure it out.

http://www.grimmjeeper.com/gears.html
Click to expand...
That's off the build sheet using the VIN. I need to verify. The shop who did most of the work on it, verified that they never changed the gear ratio. But it's 20 years old, it could have been done.
 
When I bought my '03 it had the stock sized 30" tires on it and the speedo was around 4-5 mph off. Last summer I swapped to 31" tires and now it read right on with my GPS.
 
  • Like
Reactions: TheBoogieman
willrek said:
My 2002 Sahara has been plagued with the 9mph off speedo since I aquired it in February. Love my Jeep, but really want to get this fixed since I drive it everyday. I have been through the gear change route and tried several before a forum contributer suggested it is probably the age of my speedo and a weak spring causing the error. My delima is how to best proceed with a fix, either try to find a salvage speedo cluster (which may very well fix the problem---but replacing one 20 year old guage with another 20 year old guage has me concerned about the longevity of the fix); or to use a product like the speedohealer. I've looked high and low and it doesn't appear anyone services this particular model of speedometer. Thanks to all who have helped. This forum has been invaluable to me!

Will
Click to expand...
Is it always 9 mph off or just at one particular speed?
 
Top Bottom
Back