Truck Issue

Topic 18004 | Page 1

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LDRSHIP's Comment
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I have an issue going on with my truck. Can't get a straight answer from mechanics as to what is going on. Here is what happened.

Coming in to Nashville heading south on I-65, I started the small left hand climb to where 24/65 merge. The hill is tiny and the grade isn't steep. My High Exhaust temp light came on and I loss power. Had to down shift all the way to 8th gear (10 Speed eaton fuller transmission) to make the tiny climb. The engine was running real rough. As soon as I started down hill the hot exhaust light went out and the engine smoothed out. On flat ground or down hill truck seems to be running correctly. Going up hill different story. After sitting for a couple hours it hasn't repeated yet. The only light was the high exhaust temp. No check engine light or anything.

Seminole Wind's Comment
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Patrick I know its not a school bus, but do you have a regen system? (Exhaust filter) I know when my bus wont climb even the smallest of hills, I havta do an exhaust regen run. I may be WAY outta my league here but it might help . .

Truckin Along With Kearse's Comment
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As a non mechanic and a girly guess would be the turbo??

LDRSHIP's Comment
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Tried to do a parked regen, it wouldn't initiate. Tried several times actually. Mechanics at a loss as to what caused. Lost too much time playing patty cake. If I end up on the side of the road I will let y'all know.

Kevin H.'s Comment
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When something like that happened to me, it was that the fuel filter needed to be replaced, but I'm sure the mechanics would have thought of that.

Daniel C.'s Comment
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When that happened to me, it ended up being a clogged air filter.

Tractor Man's Comment
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but I'm sure the mechanics would have thought of that.

I wouldn't be so "sure" of what some mechanics know or don't know.


murderspolywog's Comment
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Hi exhaust temp light, this could be a lot of things. Eather your truck was doing a regan. Or it had an lean fuel air mixture this will cause miss firing /hesitation, and the list of things that could cause that are everything in the fuel/air system. No check engine light so I would say it's not a problem the computer picked up on. Can you see your exhaust pipe?

Rick S.'s Comment
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Tried to do a parked regen, it wouldn't initiate. Tried several times actually. Mechanics at a loss as to what caused. Lost too much time playing patty cake. If I end up on the side of the road I will let y'all know.

Sounds like a clogged DPF (the filter that stuff gets burned out of in a regen). Regen won't initiate sounds suspicious too. Odd that you're not setting codes though - especially with the excessive ET warning.

What do your turbo pressures look like - especially under load? They should be abnormally low with a clogged exhaust output, as you can't flow enough out the pipe to spin up the turbine to proper speed (loss of power under load - if you were doing an ECM De-Rate, you'd get a light and set a CEL code).

I had similar symptoms in my supercharged corvette (I know - apples to oranges) - but my boost pressures were abnormally HIGH because of clogged cat's (lucky I didn't blow a head gasket). Ended up knocking the stuffing out of the cats and welding in a pipe (cat bypass, that looked like a cat).

Let us know what it turns out to be. Every problem and resolution adds to the database of common knowledge here.



When a violation by either a driver or company is confirmed, an out-of-service order removes either the driver or the vehicle from the roadway until the violation is corrected.

Rick S.'s Comment
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Something else I found related to High Exhaust Temp Light

Slow (10-second) flashing indicates a regeneration (regen)is in progress.

IMPORTANT: When the HEST lamp is illuminated, do not park the vehicle near flammable material.

Solid illumination indicates high exhaust temperatures at the outlet of the tail pipe when speed is below 5 mph (8 km/h).

Doesn't really explain the de-rate or failure to manually invoke a ReGen - and if the ReGen was failing, it should set the CEL and a Code.


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