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Topic: Allison HT-746 ATEC "Dont shift alarm"  (Read 541 times) previous topic - next topic

Allison HT-746 ATEC "Dont shift alarm"

Hi there-

I purchased my '93 U300 40' around a year ago and have run her 3000 miles.  Recently I went to take her out and immediately got alarm code on the Allison pad "don't shift" and she wouldn't clear first gear.  Parked her and unplugged the wire harness connections and blew them out and reconnected and took her out again.  She ran normal for 3 miles and then alarm again and no shifting.  Anyone have this issue?  I have her set to go to new transmission shop for diagnosis and repair Friday.  My old shop no longer works on buses or RVs...

Just curious if anyone else experienced this with the Allison HT-746 ATEC...and what the results, repair happened to be...many thanks

JL

Re: Allison HT-746 ATEC "Dont shift alarm"

Reply #1 –
JL,

Did you check the  ATEC code flasher light under the dash.  There is a switch for it that will flash the codes with the ignition on.

5 years ago I had a problem with a check trans light on, alarm beeping and flashing a code 32 (direction signals).  I was having hesitation shifting from Neutral to Drive. I didn't get the do not shift light.  Drove it to Mobile where the Allison Repair shop dropped the pan, found some sludge and metal, cleaned the Valve Body and replaced the Forward and Reverse Direction switches.  Changed the transmission oil and pan gasket, checked pressure, and no problems since.  Repairs were $385 as opposed to $6500 for a rebuild.  The HT746 is electronically controlled and a very rugged transmission. 

Jerry


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Jerry and Cindy Maddux
1993 U300/36WTBI DD6v92TA
build 4271  "Miss Lou"
1995 suzuki sidekick 4x4 toad
Gulfport, Ms

"Pride of Ownership"

Re: Allison HT-746 ATEC "Dont shift alarm"

Reply #2 –
Many thanks Jerry..I sent your comments to repair shop!