Stuck in limp mode

[ewo1]

No I don't have access to servicemax.

It isn't overheating.

Pulling codes thru the dash works but with servicemaxx you can view other parameters that are helpful with troubleshooting.

On you gas pedal sensor, simple cleaning is not enough. These sensors now have hall effect sensors which you cant check with a meter but if you can do 40 mph it is safe to say it is somewhat working.

My bus had a sensor issue, bus rolled but barely, new pedal sensor and problem solved.

 

[ewo1]

So what is your plan of attack now???

I realize your check trans light is not coming on but without any testing software available your in between a rock and another bigger rock!

Just for kicks, go to this thread and learn how to reset your TCM. I am in no way saying this is your problem but at least you can a) give it a try and see if there are any changes in drivability and b) learn how to reset your tranny computer. this could be useful someday in the future, you never know!

https://www.skoolie.net/forums/f37/resetting-check-trans-light-44000.html

I was taking a look at the codes you posted earlier. what kind of stands out to me is the 626 Unexpected reset fault code. Why did this one occur???

626 Unexpected reset fault code - is a power or ground issue to the ECM. Check the ECM clean power harness in the battery box, all of its connections and fuses. Follow that harness from the batteries to the ECM. Check the ECM power relay as well. Look for loose connection and or melted plastic, corroded connections along the way.

134 APS signal and IVS disagree - This could have been triggered by the unexpected power loss to the ECM.

If you have a faulty loose or dirty ground then that could cause the ECM to try and find and utilize other "Grounds" within it's electrical reach which in theory could have caused the "Temperature" codes.

All this is wild from the hip, troubleshooting. I am not there to see your bus and your not providing enough info to go much more forward.

Are you yourself handy enough to use a multimeter and get your hands dirty to check some things out?

Your ECM has an inline fuse that powers it up, usually located in the battery box. If that wire, inline fuse holder or connector has been overheated and/or just plain loose and dirty you can expect to see weird operating issues with the bus.

find that fuse, remove the fuse from the holder. Inspect the legs of the fuse. are they both clean or are they dirty/black?
also check the terminals inside the fuse holder for the same conditions.

Check the actual connection to the battery too.

 

[cadillackid]

So what is your plan of attack now???

I realize your check trans light is not coming on but without any testing software available your in between a rock and another bigger rock!

Just for kicks, go to this thread and learn how to reset your TCM. I am in no way saying this is your problem but at least you can a) give it a try and see if there are any changes in drivability and b) learn how to reset your tranny computer. this could be useful someday in the future, you never know!

https://www.skoolie.net/forums/f37/resetting-check-trans-light-44000.html

I was taking a look at the codes you posted earlier. what kind of stands out to me is the 626 Unexpected reset fault code. Why did this one occur???

626 Unexpected reset fault code - is a power or ground issue to the ECM. Check the ECM clean power harness in the battery box, all of its connections and fuses. Follow that harness from the batteries to the ECM. Check the ECM power relay as well. Look for loose connection and or melted plastic, corroded connections along the way.

134 APS signal and IVS disagree - This could have been triggered by the unexpected power loss to the ECM.

If you have a faulty loose or dirty ground then that could cause the ECM to try and find and utilize other "Grounds" within it's electrical reach which in theory could have caused the "Temperature" codes.

All this is wild from the hip, troubleshooting. I am not there to see your bus and your not providing enough info to go much more forward.

Are you yourself handy enough to use a multimeter and get your hands dirty to check some things out?

Your ECM has an inline fuse that powers it up, usually located in the battery box. If that wire, inline fuse holder or connector has been overheated and/or just plain loose and dirty you can expect to see weird operating issues with the bus.

find that fuse, remove the fuse from the holder. Inspect the legs of the fuse. are they both clean or are they dirty/black?
also check the terminals inside the fuse holder for the same conditions.

Check the actual connection to the battery too.

she has an AT545 there is no check trans light... its a mechanical transmission.. no TCM


part of her issue sounds like the bus thinks its overheated from the coolant temp sensor codes she prsented earlier... if those codes didnt come back then i think your course of attack with the pedal sounds like the next thing to go after.. if the coolant sensor codes came back after reset. (I still dont know if she has reset her codes by pulling the fuses).. anyway if the coolant sensor codes come back.. the symptoms of 30 MOH and engine not revvng are consistent.. as the computer wont completely shut it down but it will limit the power output and RPM..


she says its not truly overheating so id suspect a coolant temp sensor... there was also a low coolant level code.. lots of inconsistency here..

 

[SkullGirl]

Ok...we put the new fuel filters in and made sure everything was ok with the turbo connections. We was able to get up to 45mph on a straightaway...but Loss speed going up any kind of incline (30-35mph) After one of the inclines it started reving, surging (dont know quite how to explain it). We pulled over to let her rest and see what happens. (We made it 33 miles)

 

[SkullGirl]

she has an AT545 there is no check trans light... its a mechanical transmission.. no TCM


part of her issue sounds like the bus thinks its overheated from the coolant temp sensor codes she prsented earlier... if those codes didnt come back then i think your course of attack with the pedal sounds like the next thing to go after.. if the coolant sensor codes came back after reset. (I still dont know if she has reset her codes by pulling the fuses).. anyway if the coolant sensor codes come back.. the symptoms of 30 MOH and engine not revvng are consistent.. as the computer wont completely shut it down but it will limit the power output and RPM..




she says its not truly overheating so id suspect a coolant temp sensor... there was also a low coolant level code.. lots of inconsistency here..

It isn't overheating at all...guage says it is under 190. Took radiator cap off and it doesn't bubble.
Pulled and checked all fuses.
We cleared all flash codes...now is coming up with 111.
We have replaced the air compressor, air filter, fuel filters (both primary and secondary) , coolant temp sensor, oil sensor, and air sensor. We have checked all the wires and cleaned all the connections.

 

[nikitis]

45MPH seems like the bus is speed locked. Many AT545's were speed limited locked to 45 to keep them lasting longer. A AT545 won't run at 55MPH+ for a long time, it will grenade.

I have an AT545, and mine was speed locked to 45MPH. This is common for buses with this transmission as the schools would lock them down for safe driving.

What I think is happening is if you have 111, everything is good, the ECM is road speed limiting it to 45. You'll need a dealer or someone with Godmode servicemaxx to unlock your bus. This can be verified with the free version of servicemaxx that it's locked or not.

Free version of servicemaxx still requires a USB Nexiq Device or clone so you can plug into the network of your ECM and see the values which if you catch it at the right time can go for $250, but that's mostly just for viewing. A lot of the ability to change requires a dealer to make the changes.

Unlocks cost about $400 from a dealership. Someone with Godmode Servicemaxx could do it for free if you can get to someone with it.

I'll also let you know now, even if you get it unlocked the max you're likely to go in that bus is around 65MPH tops, which is better than 45MPH, but the AT545 won't like running at 65MPH all the time, it will overheat and wear out fast. 55MPH it can do a little better but even that will slowly wear it out just not as fast as going 65MPH all the time and you can at least drive on backroads fast enough.

Do you happen to know your rear gear axle ratio? And where did you say you lived at?

 

[BamaBus]

And where did you say you lived at?

Stuck in Ceader Rapids Iowa .

Ok...we put the new fuel filters in and made sure everything was ok with the turbo connections. We was able to get up to 45mph on a straightaway...but Loss speed going up any kind of incline (30-35mph) After one of the inclines it started reving, surging (dont know quite how to explain it). We pulled over to let her rest and see what happens. (We made it 33 miles)

If changing the filter got you 10 more mph I wonder if you checked the pre-filter just before the main filter? It has about a 3 inch long plastic housing with splines. It unscrews to reveal a round check ball and a screen. Make sure the screen is clear and the ball is not deteriorated.

What are the rpms at 45mph and when it revs, surges what happens to the speed? Transmission fluid level ok? Transmission filter changed?

 

[SkullGirl]

Help
I have a 2000 3800 t444e IH school bus compressor went down which cause bus to go into limp mode. No reving of engine while driving, but wont go past 3rd gear or over 35 miles an hour. Paid a shop $2000 for the work and new compressor but still stuck in limp mode. Anyone know how to get bus out of limp mode?
Stuck in Ceader Rapids Iowa .
No clue where to turn or what to do .
Checked and cleared all codes,rechecked no codes listed other than 111 which is no earor codes .
Can someone please help?

Ok...I just found out I had some miss information...it is a 2000 International 3800 7.6 DT466. Does that make a difference.

 

[SkullGirl]

Help
I have a 2000 3800 t444e IH school bus compressor went down which cause bus to go into limp mode. No reving of engine while driving, but wont go past 3rd gear or over 35 miles an hour. Paid a shop $2000 for the work and new compressor but still stuck in limp mode. Anyone know how to get bus out of limp mode?
Stuck in Ceader Rapids Iowa .
No clue where to turn or what to do .
Checked and cleared all codes,rechecked no codes listed other than 111 which is no earor codes .
Can someone please help?

Ok...I just found out I had some miss information...it is a 2000 International 3800 7.6 DT466.

 

[SkullGirl]

If changing the filter got you 10 more mph I wonder if you checked the pre-filter just before the main filter? It has about a 3 inch long plastic housing with splines. It unscrews to reveal a round check ball and a screen. Make sure the screen is clear and the ball is not deteriorated.

What are the rpms at 45mph and when it revs, surges what happens to the speed? Transmission fluid level ok? Transmission filter changed?

Are you referring to the water separator? Water separator was changed with the fuel filter. RPMs ar at 2800 consistently...from 25 mph up. Fluids are full. When it surged...speed dropped to 15...couldn't get any more out of it. Had to drive 6 miles like that. RPMs stayed at 2800

 

[SkullGirl]

45MPH seems like the bus is speed locked. Many AT545's were speed limited locked to 45 to keep them lasting longer. A AT545 won't run at 55MPH+ for a long time, it will grenade.

I have an AT545, and mine was speed locked to 45MPH. This is common for buses with this transmission as the schools would lock them down for safe driving.

What I think is happening is if you have 111, everything is good, the ECM is road speed limiting it to 45. You'll need a dealer or someone with Godmode servicemaxx to unlock your bus. This can be verified with the free version of servicemaxx that it's locked or not.

Free version of servicemaxx still requires a USB Nexiq Device or clone so you can plug into the network of your ECM and see the values which if you catch it at the right time can go for $250, but that's mostly just for viewing. A lot of the ability to change requires a dealer to make the changes.

Unlocks cost about $400 from a dealership. Someone with Godmode Servicemaxx could do it for free if you can get to someone with it.

I'll also let you know now, even if you get it unlocked the max you're likely to go in that bus is around 65MPH tops, which is better than 45MPH, but the AT545 won't like running at 65MPH all the time, it will overheat and wear out fast. 55MPH it can do a little better but even that will slowly wear it out just not as fast as going 65MPH all the time and you can at least drive on backroads fast enough.

Do you happen to know your rear gear axle ratio? And where did you say you lived at?

We have had the bus for a little over a year...haven't had a bit if trouble with her. She is governed at 60. We usually run about 57mph. We don't really live anywhere particular...just travel. We are in Mount Pleasant Iowa right now.

Is there any way to get it out of speed lock by myself?

 

[Omnibot2000]

Dt466e can derate when hot even when not what some say to be overheating.

We had these engines move like slugs. Max 70 kph. Rad was often plugged. No buzzers, no lights, no nothing but a temp gauge sitting around 210-215 and engine fan on all the time.

What does the temp.gauge say?

 

[Omnibot2000]

Dt466e can derate when hot even when not what some say to be overheating.

We had these engines move like slugs. Max 70 kph. Rad was often plugged. No buzzers, no lights, no nothing but a temp gauge sitting around 210-215 and engine fan on all the time.

What does the gauge say?

Edit: I've also come across other engines that will slowly rev up and accelerate with a dead TPS. Typically when the idle validation switch is released and TPS shows zero the engine can give you a very slow gradual increase in engine speed to move the truck. Just cannot remember if this also applies to the DT you have

 

[BamaBus]

Dt466e can derate when hot even when not what some say to be overheating.

We had these engines move like slugs. Max 70 kph. Rad was often plugged. No buzzers, no lights, no nothing but a temp gauge sitting around 210-215 and engine fan on all the time.

What does the gauge say?

Edit: I've also come across other engines that will slowly rev up and accelerate with a dead TPS. Typically when the idle validation switch is released and TPS shows zero the engine can give you a very slow gradual increase in engine speed to move the truck. Just cannot remember if this also applies to the DT you have

Would the rpms be 2800 at 25mph and up with the plugged rad and tps issue?

 

[BamaBus]

Are you referring to the water separator? Water separator was changed with the fuel filter. RPMs ar at 2800 consistently...from 25 mph up. Fluids are full. When it surged...speed dropped to 15...couldn't get any more out of it. Had to drive 6 miles like that. RPMs stayed at 2800

The prefilter, sometimes called a rock catcher is in the fuel supply line just before the filter. The water separator should be before it under the bus or on the other side of the engine.

Your problem is not a "speed lock" or a speed limiter and not a rpm limiter. It doesn't appear to be a fuel issue.
To me it seems to be a restriction like a locked-up service brake, parking brake (if hydraulic brakes). If you have air brakes, does it build and hold pressure? Was the governor on the compressor replaced? Was it reinstalled correctly? I have a bus that sat in GA for a year to find out the school system blocked off the exhaust port for the governor.

OR a bad transmission. Is it shifting through all gears? Just saw in your original post that it wouldn't shift out of 3rd. Have you lost 3rd and now in 2nd gear? After all its a 545

 

[nikitis]

Yeah if you drove on it before the work at 60MPH it's likely not road limited.

2800 RPM isn't an engine limp. Limp mode doesn't allow engine to get that high as far as I know. Seems like transmission won't shift out of 2nd and it's revving but not switching, so I agree, could be transmission.

Waiting for the day my 545 does this too.

 

[Omnibot2000]

Would the rpms be 2800 at 25mph and up with the plugged rad and tps issue?

Did not see this thread had a page 2

 

[SkullGirl]

Dt466e can derate when hot even when not what some say to be overheating.

We had these engines move like slugs. Max 70 kph. Rad was often plugged. No buzzers, no lights, no nothing but a temp gauge sitting around 210-215 and engine fan on all the time.

What does the temp.gauge say?

Temp runs around 190-200°

 

[SkullGirl]

The prefilter, sometimes called a rock catcher is in the fuel supply line just before the filter. The water separator should be before it under the bus or on the other side of the engine.

Your problem is not a "speed lock" or a speed limiter and not a rpm limiter. It doesn't appear to be a fuel issue.
To me it seems to be a restriction like a locked-up service brake, parking brake (if hydraulic brakes). If you have air brakes, does it build and hold pressure? Was the governor on the compressor replaced? Was it reinstalled correctly? I have a bus that sat in GA for a year to find out the school system blocked off the exhaust port for the governor.

OR a bad transmission. Is it shifting through all gears? Just saw in your original post that it wouldn't shift out of 3rd. Have you lost 3rd and now in 2nd gear? After all its a 545

It does build and hold pressure. Iam not sure if the governor was replaced. I had the work done at Pappas Trucking in Cedar Rapids...I ASSUME it was done correctly.

I hope it isn't the transmission...how can I check to see if it is?

 

[SkullGirl]

Dt466e can derate when hot even when not what some say to be overheating.

We had these engines move like slugs. Max 70 kph. Rad was often plugged. No buzzers, no lights, no nothing but a temp gauge sitting around 210-215 and engine fan on all the time.

What does the gauge say?

Edit: I've also come across other engines that will slowly rev up and accelerate with a dead TPS. Typically when the idle validation switch is released and TPS shows zero the engine can give you a very slow gradual increase in engine speed to move the truck. Just cannot remember if this also applies to the DT you have

What is Rad?