cbnnt1 Posted June 20, 2009 Share Posted June 20, 2009 My 88 mack will not up shift when to the floor. A trans shop says its a power problem. How does the trans know where the throttle is Any advise?? Quote Link to comment https://www.bigmacktrucks.com/topic/9801-will-not-up-shift/ Share on other sites More sharing options...
Noid93 Posted June 20, 2009 Share Posted June 20, 2009 (edited) There is a "kick down" as well on the allisons. If u have an air throttle that moves a air cylinder on the injection pump, it uses the same air pressue pushing agianst a little cylinder and spring to move a linkage on the tranny to tell it how much throttle you are giving it. First thing, you need to find out if it is a cable modulator or air modulator. If it is a cable modulator it can be adjusted if it is not broken. Remove the end from the transmission, which is located on the left hand side (in your case the passenger side) just above the top of the oil pan about 2/3 of the way back. There will be a pin inside. Have someone step on the throttle to see if the pin moves in and out with the throttle. The engine may have to be running to do this. If the cable is not broken, then locate where the cable attaches to the throttle linkage. At full throttle you should be able to pull the end of the modulator cable about 1/8" past the throttle linkage. If you have an air modulator(located same spot) Remove the air cylinder. Apply shop air to the air inlet side of the air modulator. If any air leks by to the plunger side of the modulator, replace the modulator."Hope that helps Edited June 20, 2009 by Noid93 Quote There Is No Replacement, For Displacement!!!!! Link to comment https://www.bigmacktrucks.com/topic/9801-will-not-up-shift/#findComment-36964 Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.