Allison delayed shift from 4th to 5th

[sjohn116]

Let me preface my question with "I havent yet flushed the transmission as outlined previously, from 15w40 to ATF."

that being stated,

When driving around the neighborhood, my m1081 has a distinct hesitation/delay when trying to shift from 4th to 5th gear.

2nd to 3rd is abrupt and crisp like everyone else reports, due to large difference in gearing.
3rd to 4th is uneventful, engine spools up, feels like it should be shifting into 5th, wait for it...wait for it...sounds like it shifts out of 4th. slips. and then goes into 5th
5th to 6th is uneventful
6th to 7th is uneventful

downshifting is uneventful throughout the range 7th->->->->->2nd

Have you encountered the same or something similar in your LMTV, and/or, is this a worn clutch in the transmission, a WTEC issue, or something else?

 

[NDT]

Have you pulled codes?

 

[Suprman]

What's your charging voltage at?

 

[PowerstrokeNC]

subscribed

 

[Jakelc15]

If this is an abs truck and it isn't working it can effect shifting

 

[Jakelc15]

Just noticed that your pretty close to me

 

[sjohn116]

I havent yet checked for codes in the transmission; and the alternator is charging at 27V.

This weekend is already shot changing the oil pan gasket and filters, I'll try to address the trans shifting issue in the upcoming weeks.

Does the truck have to be running to pull codes, or can I do it with just the master switch on, engine off? Forgive me for asking, what is the protocol to pull the codes and where is the list/legend to "decrypt" the codes? Thanks.

You're right, I'm not far from you. I'm in 21791.

 

[Suprman]

Arrow up and arrow down at the same time. Is your speedo accurate or jumpy?

 

[sjohn116]

Speedo is smooth and accurate. Ditto for volts, temp, and air tank pressure.

Fuel is jumpy when driving, but I dont trust it to begin with. Probably have a loose wire somewhere in that circuit.

 

[Suprman]

Fuel sender has a connection on tank that can come loose. The trans comp uses input from several sensors to determine when to shift. Mil trucks in general have harsh shifting. Was there any codes? The trans comp is very good at self diagnosing.

 

[sjohn116]

d1 21 23 is the only code stored in the WTEC

 

[Suprman]

21 23 bad throttle position sensor. Its a black box above the primer/fuel filter with a cable going to the throttle on the fuel pump.

 

[sjohn116]

my apologies: codes are as follows:

d1 21 23 = TPS failure (f12)
d2 45 21 = open circuit (f7)
d3 43 21 = low side driver (f
d4 43 26 = low side driver (f
d5 45 26 = open circuit (f7)

 

[Suprman]

Replace the tps and then clear the codes and see what happens

 

[Jakelc15]

//cloud.tapatalk.com/s/581cb9724c164/Codes Allison 1000 2000.pdf

Allison codes

 

[coachgeo]

//cloud.tapatalk.com/s/581cb9724c164/Codes%20Allison%201000%202000.pdAllison codes

This is probably a GREAT START manual. Are these universal Allison codes though? Ask cause this manual of codes is for the 1000 and 2000 model and ours is based on the 3000 model. Then there would be codes for the AWD/Transfer case attached to back of the Tranny that won't be in this manual

 

[Jakelc15]

The codes are all the same. There should be a manual in the tms forum too

Sent from my SPH-L710 using Tapatalk

 

[sjohn116]

Got the new TPS, installed it exactly where the old one was positioned, and it required about 1/4-1/2" of cable to be pulled out (from the fully retracted position) to connect the TPS to the throttle body linkage with the cotter pin. Seems to me that the cable should be in the fully retracted position when the engine is in the idle position, in order to give the TPS a true ZERO reading. Is my thinking flawed, or correct? If correct, there looks to be a lot of adjustment in the TPS mounting bracket, loosed 4 bolts, and slide the assembly forward 1/4-1/2", until there is no tension on the cable at idle. Am I right or am I wrong? Thanks in advance. After I sort this out I'll clear all the transmission codes and see which, if any, codes return.

 

[Suprman]

The repair tm should have an alignment procedure if there is a specific one.

 

[sjohn116]

TM states "4 inches between throttle connector and the groove in the cable." Doesnt mention whether or not the cable is partly extended to reach that 4" Oh well...will follow the TM explicitly, clear out the codes and throttle count, and call it a day.