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While i was pulling my trailer thru Georgia, was going up hills and the tranny would down shift from 5 to 4, then it would stay in 4th gear unlocked with engine light on. Code p0700, and p1621. Did this about 5 times had to pull over and reset codes . Am i in trouble
 

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While i was pulling my trailer thru Georgia, was going up hills and the tranny would down shift from 5 to 4, then it would stay in 4th gear unlocked with engine light on. Code p0700, and p1621. Did this about 5 times had to pull over and reset codes . Am i in trouble
yup. limped the trans. Now it will be quicker to limp under less of a load too. what did you have your edge set at?
 

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What level are you towing with on your programmer?

Sounds to me like you should start saving for a built trans, since you've already started limping your stock allison. They can only take about 80-100hp over stock as it is, let alone with a load/building boost in 5th as it is the weak link.
 

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ugh, double post :rolleyes:
 

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I would set it back to stock and be easy on the 4-5 and 5-4 shifts. Start saving up for a trans like nvrplzd said
 

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Wow. I have the same problem. STOCK truck, only a little over 115k, mostly a daily driver and towing an 18' enclosed low profile v-nose motorcycle trailer with only a bike and some tools in it. I bought this truck mainly because of the Allison and now it craps out. Yes, I changed the fuel filter. It didn't help.
 

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Wow. I have the same problem. STOCK truck, only a little over 115k, mostly a daily driver and towing an 18' enclosed low profile v-nose motorcycle trailer with only a bike and some tools in it. I bought this truck mainly because of the Allison and now it craps out. Yes, I changed the fuel filter. It didn't help.
Let me guess, you bought it used?
 

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Yeah, I did. About 60,000 miles ago from a gentleman who retired hoping to travel with his new RV. He made 2 trips to Florida and I got a good deal on a great truck. It hasn't been beat on.
 

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So he never tuned it? all old guys aren't innocent for wanting power.
 

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You should have the code read--the 700 just shows you may have a trans problem-- there are other codes. That will help diagnose the problem. Cheap readers do not read trans codes. Maybe an auto parts will read them for you.

The 1621 is a computer error-- I don't think it is the main problem.
 

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No he never did, and neither have I. I have been considering a basic programmer for maybe a little better MPG. I doubt he even knew you could hop one up. I never have for tbe simple fact I wanted to be safe when towing- but I don't do a lot anyway, and when I do its not that heavy. To sum it up- I don' think this was caused by abuse. I posted in another thread and got some replies about the FPRV causing similar symptoms. Gonna try that first...
 

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Here is the botle test-- that will check the FPRV. - At the rear of the driver's fuel rail, there is a 3/8 "U" shaped hose-- remove the 3/8 hose from the rail fitting, and plug the hose. Attach a long 3/8 hose to the rail fitting and put the end in a bottle. Now drive the vehicle hard-- if you have fuel in the bottle, the FPRV is bleeding off rail pressure. You need to shim the valve, or replace with a race valve [plug] that will not bleed pressure
 

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Thanks for the info on the bottle test. It will surely give me a little better piece of mind before I make the wrong conclusion. I'll do a search for the procedure, maybe it will have some pics. Thanks again.
 
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