not a problem

 

Something to consider, I found this out quite by accident:
1. fuse blows out on my tail lights from sub-standard wiring job(rigged tail light hook up I had to perform on the fly)
2. I am on the interstate without a extra fuse(good thinking on my part!)
3. I locate blown tail light fuse and remove it.
4. I substitute another fuse from the block in place of blown tail light fuse.
5. Next morning have to load a Tractor onto trailer and pull it back home.
6. Start driving and go to press overdrive switch for heavy load and nothing happens.
7.Realize that fuse I substitutied for tail lights the night before was the Over drive fuse.
8. Remove Another fuse in block to take place of OD fuse so I can have tail lights and OD(Am I seeming stupid YET!?!?!)
9. This fuse is from the instrument cluster.
10. This is the interesting part, the OD light starts flashing as soon as I put the fuse in the OD curcuit but, even though it keeps flashing I can switch it in and out of overdrive(meaning to me that is not really in limp mode)
11. Theory is that the light or the sensor that makes the light flash can be fooled for what ever reason into a false limp mode pattern even when it is not acually in limp mode.
12. I think it must be something simular to the wait to start light that stays on when you start the truck after you have been driving and the glow plugs don't need to be on, the light cycles on anyway. I have no technical data on why this is happening, I just noticed this the other day, so what ever its worth i hope it might send you in the right direction in your search.

 

I am sure glad that they only thing on my rig that has a computer is the tranny. I would like a powerstroke cause of the chipping you can do, but I don't think I really want the hassle. As long as it isn't the lose nut behind the wheel. Thanks for taking the time to list out your experiences. It will defenitly help me in the summer and fall months ahead.

 

The slipping tranny code sets at a certain slippage point when the input shaft speed coming out of the t/c exceeds the output shaft speed going into the t-case by a certain amount. ( Have no idea if it's 1 rpm or what.) At low rpm the pump in the tranny may not be putting enough pressure into the clutches to keep them applied to prevent slipping. Especially considering that the p-stroke is supposed to put out 500+lb/ft at 1600 rpm. ( Memory is vague here.) 1600 is pretty close to the stall speed for the t/c, so that would mean roughly 900+ lb/ft.( Maybe more depending on torque multiplication) 900 lb/ft bumped up against 6-7K lb truck trying to climb up a ledge or move a heavy load overcoming initial friction. That adds up to a lot of stress on those little clutches bathed in light oil. If I had to guess, I would say that you have worn clutches combined with a little less pressure than you need added to a whole lot of torque, chained to a temporarily stationary object= slippage. Pull the 4 low lever and save the tranny. It's an old trick that has been used for years with smallblocks and big trucks with autos. Some tranny guys might disagree, but I would state that more trannies have been gutted at the stall speed of the t/c trying to do just what you say, than just about any other method. Slippage of t/c adds heat. Heat makes fluid thinner. Thinner fluid holds less pressure through worn components. Temps build then slippage starts which burns up clutch material and blues the steels. Next thing you know, it's off to the $3,000 dollar store for a new tranny.

 

Thanks for the awesome description. I think you have summed up what is going on with my tranny. I like that 4 low trick and will use it for sure, espically since I don't have an extra $3000 kicking around. Thanks again for the help.