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Allison 5-speed auto - No reverse - Blinking R
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Post Allison 5-speed auto - No reverse - Blinking R 
This happened to me yesterday...

Truck sits a garage most of the time and is only used about once every 2 weeks. It's colder than hell here so I'm wondering if that had something to do with this issue. Garage temp was about 40*F when I backed it out. Outside temp right about -5*F. Drove the truck about 20 miles to pick up a water heater. When I got to the warehouse location, I tried to turn around in the parking lot and had no reverse whatsoever. The instrument panel indicator simply blinked the R continuously. Put the selector back in D and forward gears worked fine...still, no reverse. Shut the truck off and restarted, no change. So, I decided to just shut it off while I went inside to get my business taken care of. This took about 15-20 minutes. Came back out expecting to have to drive through their grass because I can't back up but everything was back to normal. Have not had a problem since. Did I just have a stuck valve in the transmission somewhere or what? If so, how do I prevent this in the future?

2002 Silverado 2500 HD
8.1L, Allison 5-speed automatic
Approx 41,000 miles on the odometer

Thanks
Todd

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it is possible that there was moisture or condensation inside the trans, and upon hitting the really cold air it froze a valve. and while you were inside heat soak finally melted it and freed it up. thats the only thing i can think of - i dont know what the flashing "R" indicates, just spit balling.

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Post Re: Allison 5-speed auto - No reverse - Blinking R 
ToddH-2500HD wrote:
This happened to me yesterday...

Truck sits a garage most of the time and is only used about once every 2 weeks. It's colder than hell here so I'm wondering if that had something to do with this issue. Garage temp was about 40*F when I backed it out. Outside temp right about -5*F. Drove the truck about 20 miles to pick up a water heater. When I got to the warehouse location, I tried to turn around in the parking lot and had no reverse whatsoever. The instrument panel indicator simply blinked the R continuously. Put the selector back in D and forward gears worked fine...still, no reverse. Shut the truck off and restarted, no change. So, I decided to just shut it off while I went inside to get my business taken care of. This took about 15-20 minutes. Came back out expecting to have to drive through their grass because I can't back up but everything was back to normal. Have not had a problem since. Did I just have a stuck valve in the transmission somewhere or what? If so, how do I prevent this in the future?

2002 Silverado 2500 HD
8.1L, Allison 5-speed automatic
Approx 41,000 miles on the odometer

Could be a loose ground or wire connector. Not sure Confused

Thanks
Todd


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My cousin has been to Allison transmission school and builds these things all the time called him up he says check your plugs to the trans these years are known to not be connected properly from the factory. Also tells me the trans computer will note the problem and store it for 20 or so key cycles then get rid of it. The flashing indicater lite tells him the trans wasnt absolutely sure what gear was selected so it did nothing..... a bad connection or problem internally would cause this but without his laptop connected to it he wont speculate. For a 1 time thing his shop would ignore it if it does it again bring it to an Allison guru. He works for a Detroit diesel/ Allison trans dealership and says GM dealers normally dont have an expert on hand check with a big truck dealer in your area. ....little known allison fact...some models come with 6 gears but the computer is programed to only use 5....hope some of this rambling helps ....Lorne

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Truck did this again today, second day in a row. In messing with it, I made it happen several times. It would blink the R, and not move. Shut it off, then start back up and it would be fine. Finally when driving the last stretch home, Check Engine came on. Scanned codes when I got home and found P0700 and P0743 (Torque Converter Clutch Circuit Electrical).

I will check connections tomorrow...hoping it's that simple!

Thanks for all the input guys!!!
Todd

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From what I could tell laying on my back on the garage floor, all connections are tight. In fact, they were so tight I wasn't able to simply unplug and replug. Sometimes a hoist would be REALLY nice! I guess I'm going to have to contact an Allison shop.

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damn, sounds like a trip to the dealer, or at least someone that can plug in. not sure how ling it records information or how many times. may just be a control module issue, hope its not something mechanical.

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Have not yet been to a dealer. Truck worked fine all day yesterday. Today, on the way in to work SES went off. Got to work, shifted to Reverse and...NOTHING but a blinking "R"! Grrr...

Even though no power is transferred to the wheels when the R indicator is blinking, I *CAN* feel it doing something when shifting between "R" and "N". Engine rpms fluctuate slightly and you can feel a slight "bump" like you'd expect when putting it into gear.

I dread going to the dealer for fear of "cannot duplicate" and/or replacing parts in a shotgun fashion and never really fixing the issue.

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ToddH-2500HD wrote:
Have not yet been to a dealer. Truck worked fine all day yesterday. Today, on the way in to work SES went off. Got to work, shifted to Reverse and...NOTHING but a blinking "R"! Grrr...

Even though no power is transferred to the wheels when the R indicator is blinking, I *CAN* feel it doing something when shifting between "R" and "N". Engine rpms fluctuate slightly and you can feel a slight "bump" like you'd expect when putting it into gear.

I dread going to the dealer for fear of "cannot duplicate" and/or replacing parts in a shotgun fashion and never really fixing the issue.


Try taking video with a camera/camera phone and show the video to the dealer to avoid the can not duplicate problem issue.

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Found this on The Diesel Page from over 4 years ago:

blakmax10-10-2004, 12:24 PM
Friday a 2002 d/a shows up at the shop with no reverse and a tcc code. Sorry, I wrote the code down and left it at the shop. I had the laptop on it and tested the F solenoid which tested okay!
I have been searching for hours hoping someone might have had this problem. Monday I will start the hunt for wiring problems. tongue.gif tongue.gif

--------------------------------------------------------------------------------

blakmax10-11-2004, 07:04 PM
Fixed! Solenoid F failed. Started with Allison troubleshooting for code P0743. F solenoid was open. Tim



Anyone have a part number for the "F Solenoid" and know where it is located? Do you have to remove the pan to get to it?

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TCC PWM Solenoid
Part #: 8683187
$51.30

8 Qts ATF DEX-III
$36.00

Labor
$257.95

Envirn.Misc Fees
$30

Total with Tax
$397.47

So far, everything is working fine. This was not something I was expecting on a 42,000 mile truck!

Thanks everyone for the help!!!
Todd

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