[navistar45]

ok ih guy's,i have a spedo issue on my 95 model 4900. the 95 i bought a few months back had a couple item's missing[turn signal.intrument cluster]. no prob,i bought a new turn sig [$175.00 w.t.h ?]and took the instrument cluster out of one of my 95 model school buses,installed it in the 4900. well here's my prob, everything works fine but the temp gauge[sender is good ],and the speedo is inaccurate. i'am sure the spedo prob is due to the difference between axle ratio's of the bus and the 4900. my question,how do you calibrate the speedo to match the axle ratio? i have seen the spedo adjusment on the back of the cluster ,but what's the proper procedure/code? thanks, jim ..

 

[navistar45]

sorry guy's for the slow response, had a issue come up. anyway, my tire size is 295-75-22.5 , 4.44 axle ratio , and spicer 7spd direct tranny. this is a mech injection truck. thanks for the help guy's..

 

[navistar45]

thanks duke,i doubt the difference between the tires is worth worrying a about. if i understand y'all correctly,i just program the numbers to the ones you gave me,then i'am good to go!? if my temp gauge cant be fixed easily,i may pull another cluster from a bus that i know works,i will program that speedo while i have it out.

 

[navistar45]

just got to rain on my parade dont ya!

 

[navistar45]

ok guys,got the spedo set, it was only one dip switch off. test run shows every thing is accurate. now to get that pesky temp gauge working, thanks for the help fella's..

 

[navistar45]

temp gauge refuses to work. when i turn the key on,it jumps a bit,but thats it. the gauge cluster is out of another bus ,that i know for a fact works. the other cluster netted the same issue, everything but the temp gauge worked. i have tested the system with a temp sender from a spare engine that also works fine, gauge works/sender works, so it must be a wireing issue! i need to obtain a schematic of the wireing,unless some one knows which wires feed into the firewall? all the wireing is protected in a loom,so i cant see why it would be damaged...

 

[navistar45]

thanks a bunch doc. now i gotta find the time to crawl around the truck,and chk the wires. sort of wondering if the issue is a ground problem, your info has likely saved me from a headache. thanks again sir...