ht740d

[haroldmc8]

ht740d will not work in forward or reverse. I have changed cable modulator to air modulator. When I put it into forward gear, it stalls engine dead. When I put it in reverse it does nothing.  This is what my problem was and some of you thought it had something to do with the modulator pin length. The problem was no modulator pin. Apparently when I removed the cable modulator and installed the air modulator, the pin fell out and went down in the oil pan. I removed the modulator to check the pin length and found that there was no pin at all. I bought a new pin from allison and installed it. That cured all of the problems,it works great now. Thanks for the help guys. haroldmc8

[makemineatwostroke]

Harold, glad it's fixed amazing the way that transmission will act with out the pin or wrong pin

[tomhamrick]

I am about to change my modulator to air. Can you explain how the pin came out and got into the pan? Is it not connected to the modulator?? How do I prevent this from happening when I make my change??

Thanks,
Tom Hamrick

[makemineatwostroke]

Tom there is no way the pin can fall into the transmission oil pan most of the time it falls into your drain pan or stays in the modulator you have a couple of gallons of oil above the pin that forces it out so if you are missing the pin look in the drain pan thats where it will be    good luck

[tomhamrick]

I will be sure to watch out for it.
Thanks, Tom Hamrick

[haroldmc8]

Tom I did a quick remove and install to eliminate to much fluid loss. I only lost about a cup of fluid and  the pin. I have no ideal where it went to, the mechanic at the Allison dealer said it probably fell into the oil pan. He wanted me to pull the pan and retrieve it. I elected to pay $7.00 for a new one instead. It is about 3/16' x 1 1/2" long. I would recommend draining the trans fluid down below the modulator level, about 3-3 1/2 gal. on mine.Remove the cable modulator carefully and look for the pin in the end of it. If it is not there,put your pinkie in the trans and see if you feel the pin. If you do go ahead and install your air modulator. I would definitely make sure the pin is in place before installing the air modulator.

[tomhamrick]

Thanks HaroldMC8.  I may want to drain the fluid down so I can take my time. I tend to make big messes when I try to do something quickly!! 
Tom Hamrick