Does anyone know the correct operators procedure for switching between low and high range in these articulated rock trucks? There is no mention in the operators manual?! There is a switch which appears to be the suspect on the dash but does nothing. I tricked out the relays to engage low on one unit, (so know the function works) as it couldn't crawl onto a low boy, now it needs looking at. Thing is, I've got two trucks side by side and neither one will shift low to high. Thanks in advance for any help on this.
from what I can understand reading the operators manual, although there is a "low range" it's in the form of a kick down when in automatic gear selection, not a separate gear selection altogether. so there is no option to actually engage a low range of gears
The following only applies to the Allison transmission. There is a gear box for high/low range. It has 2 sensors in it to determine what position the gear box is in. If the sensors are miss-adjusted or failed it will try to default back to where it thinks it was. It also may prevent you from moving, if you shut off the key and change the switch position. FYI, when dealing with terex trucks, the first 3 digits of the serial number determines the serial number break. Gen 7 trucks were made for 8 years with several serial number breaks.