I am having problems with my speedometer and am hoping that someone can offer possilbe solutions. The speedometer in my '98 FL70 (Cat 3126 w/Eaton 6 speed)works fine most of the time. About 20% of the time it will be showing half the actual speed. If I am driving 60 mph, it will drop down the 30 mph. It may stay there for a few minutes and other times it may stay there for many miles. Usually, if I shut the engine down and restart the next day, it will work fine. I have changed the sensor underneath. It improved, but is still acting up. I tried to get a new wiring harness, but Eaton keeps sending the wrong one. Has anyone else had this problem?
FL 70 Speedometer
- Thread starter Larry
- Start date
Doggie Daddy
Veteran Expediter
>Mine has done that for years, I
>pretty much drive by engine noise.
And with the mileage that you have on your truck rich,there ought to be plenty of that.
:7 j/k,i couldn't resist.
>pretty much drive by engine noise.
And with the mileage that you have on your truck rich,there ought to be plenty of that.
:7 j/k,i couldn't resist.
Had this same problem years back on 94 FL70. The speedo and tach themselves are electronic and their circuit boards develop shorts and such over time and give the intermittent wrong needle readings. With my tach I was able to fuss with the little switches on the circuit board to fix it but I had to eventually replace the speedo unit itself when it no longer read even close to right. Denny
Thanks Rich:
Every once in a while my Tach will also act up. But everyone said that the tach and speedometer are totally seperate. However, a bad ground in the dash would account for the problem. I'll pull the dash this May and let you know.
My biggest concern is when I drive through the scales. Every state has different speed limits and if there is not a truck in front of you to follow it makes it difficult keeping between 15mph and 30 mph, or at 5 mph or whatever system they decide to use.
Larry
Every once in a while my Tach will also act up. But everyone said that the tach and speedometer are totally seperate. However, a bad ground in the dash would account for the problem. I'll pull the dash this May and let you know.
My biggest concern is when I drive through the scales. Every state has different speed limits and if there is not a truck in front of you to follow it makes it difficult keeping between 15mph and 30 mph, or at 5 mph or whatever system they decide to use.
Larry
CharginCharlie
Expert Expediter
RE%3A FL 70 Speedometer
I had the same problem for a couple of years and,finally, in January, I had both the tach and the speedo replaced as they both died totally. They both work fine now.
I had the same problem for a couple of years and,finally, in January, I had both the tach and the speedo replaced as they both died totally. They both work fine now.
joebob1_30132
Expert Expediter
RE: RE%3A FL 70 Speedometer
same here told both tac and sped are seperate.. I chaned the sensor at the trans for the speed didnt help ..so I bought a new speedom there are ajstments behind it that have to be adjusted with the size of your tires..my tac idols at 10k tried to adjust it ..but could no get it to start back at o..
same here told both tac and sped are seperate.. I chaned the sensor at the trans for the speed didnt help ..so I bought a new speedom there are ajstments behind it that have to be adjusted with the size of your tires..my tac idols at 10k tried to adjust it ..but could no get it to start back at o..
RE: RE%3A FL 70 Speedometer
HI
Try running a 12 guage wire from the bracket under the dash to a good ground on the frame.If this helps then clean all body to frame ground straps and try adding 1 or 2 more. Another way to check it is to hook a wire to the neg side of battery and then touch to the bracket, if you get sparks then its not grounding properly or you have a short under the dash.Good luck.
HI
Try running a 12 guage wire from the bracket under the dash to a good ground on the frame.If this helps then clean all body to frame ground straps and try adding 1 or 2 more. Another way to check it is to hook a wire to the neg side of battery and then touch to the bracket, if you get sparks then its not grounding properly or you have a short under the dash.Good luck.
aquawarrior7
Expert Expediter
RE: RE%3A FL 70 Speedometer
ok you fl 70 guys what does it mean when the check engine light flashes on and off sometimes. When I turn it off let it sit a lil while and turn it back on it doesnt come back on till it wants to.I have had on other trucks it come on and stay on but not flash.
Thanks
ok you fl 70 guys what does it mean when the check engine light flashes on and off sometimes. When I turn it off let it sit a lil while and turn it back on it doesnt come back on till it wants to.I have had on other trucks it come on and stay on but not flash.
Thanks