Electronic malfunction light

[Jonah]

I have a 1991 mack ch613 e7 350 every time I get to 64 mph the electronic malfunction light comes on and the truck loses power I've done took it to mack but no luck I figure it's in the computer but I can't get nobody to reprogram it any help would be great Thanks

[tjc transport]

with cruise off and engine at idle, push cruise button up one time to set, than count the EML flashes. that code will tell you what the issue is. 

[Jonah]

I just tried and no flashing eml light but my cruise doesn't work ?

[Joey Mack]

no programming to be done on a '91..  check the adjustment of the speed sensor in the tranny output housing...  It goes all the way in (gently) then 1 full turn out..  you may want to remove it and check it for damage. jojo