2005 Freightliner M2 Allison w/ Cat C7 - Tranny acting up

Good Evening everyone. Got a great truck here that is acting up. Transmission wont shift out of first gear and check engine light blinks. occasionaly dash says "no trans". Was recently checked out by the local Allison shop and they said it wasn't throwing any codes. Problem has been intermittent but has recently hit wide open, causing trouble 24/7.

Bad ground?
Bad Fuse?

seems like a electrical issue. clutch test at allison went well.

Looking for direction here. Thank you in advance.

Bad TCM. I'm surprised the Allison shop didn't catch it. My service truck just did it. Exact symptoms. You can retrieve codes through the shifter display. There were times mine wouldn't even do that much. That's what I think based on my experience. Let us know what you find out.

Junkyard said:

Bad TCM. I'm surprised the Allison shop didn't catch it. My service truck just did it. Exact symptoms. You can retrieve codes through the shifter display. There were times mine wouldn't even do that much. That's what I think based on my experience. Let us know what you find out.

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Ok. Thanks Junkyard. I had suspected the TCM. Anyway to test it? or just replace and wait for magic>>

Thanks.

Dealer can test it, I'm not convinced their test is absolute based on my conversation with them and how they diagnosed when mine acted up. Seems like it was around $800 parts and labor. Mine got to where it wouldn't even move. Limped to the motel, got up the next morning thinking I was headed to dealer, worked fine all the way to the shop then nothin. Had to go in on the hook :-(. Should have gone straight to dealer. Get it done before it strands you with some very gross weight (assuming that kind of waste lol)

Getting a ECU 128 and PID 259 Code. Anyone know what this is?

Google told me it was low voltage detected at fuel shutoff solenoid

I might have seen the same post on google and called freightliner parts to see about a new "fuel shut off selonoid" and was told that part doesn't exist for my machine.

Thinking the lingo was crossed, I checked the heui driver selonoid which sits on top the fuel pump. When I unplug it I get a new set of error codes. I ohm out the selonoid and got 22 which is out of spec I think. Spec is suppose to be 6-10.

But truck seems to run fine except for the limp mode and tranny shifting rough and not out of 1rst.

related but not sure how the speedometer doesn't work as well.

Thanks yall

When a car or pick-up has those symptoms first place to look is diff, picks up signal from ring gear.
Usually the pickup is cruddy or not functioning.
I no not where big rigs get the signal.

Wastepro said:

I might have seen the same post on google and called freightliner parts to see about a new "fuel shut off selonoid" and was told that part doesn't exist for my machine.

Thinking the lingo was crossed, I checked the heui driver selonoid which sits on top the fuel pump. When I unplug it I get a new set of error codes. I ohm out the selonoid and got 22 which is out of spec I think. Spec is suppose to be 6-10.

But truck seems to run fine except for the limp mode and tranny shifting rough and not out of 1rst.

related but not sure how the speedometer doesn't work as well.

Thanks yall

Click to expand...

If the speedo is not working right, you may have a bad output shaft sensor that is the root of all your trans issues. If the trans ECM is not getting a good output shaft reading you will have problems. Including not shifting and that will show as a check engine light and limp mode issue.

To simplify this, if the TCM is not getting a good output signal to compare with engine speed it just wont shift. And it will probably cause the engine to derate.

We've got an 2009 M2 site fuel truck that had a similar problem a few years back. Ended up replacing the transmission wiring harness. From what I remember, it wasn't throwing any codes, just flashing the display.
They are making wires so small (cheap) these days that broken wires in a harness is becoming common. That's something you'd almost never see in the past.

To update :

Truck is giving error codes ECU 128 (engine) and PID 259 (not sure about this, maybe fuel pump?)

HEUI fuel pump solenoid is reading 22 oHms, I have been told it should read 8 oHms.

Check engine light is on, speedometer doesn't work and truck will not shift out of first.

Problem was intermittent for a while, you could shut truck down and fire back up and problem would go away. Been that way for 2 weeks...but now its just broke when you fire up.

Caterpillar told me the HEUI pump is on national backorder and could be weeks or months before we get one. But i'm not convinced that is our problem...

Rzucker- Are you referring to the speed sensor on the transmission at the driveline? Is it worth just replacing all speed sensors? I think there are 3.

Small update:

Had a chance to get the flash codes off the engine. Been a busy week here with this truck down and another one having some hydraulic heating issues.

To top it off, yesterday evening a 17 5R 25 IT-24 loader tire blew out while mixing food waste. Looked like a bomb went off, blowing food 100 feet out of the mixing shed!! Wish I had a video to share with everyone.

Any ways, back to the truck at hand.

Flash codes:
18-injection actuation pressure
31-loss of vehicle speed sensor
37- fuel pressure short
39- injection pressure sensor/injection activation switch/injector leak
47- PTO shutdown/Idle shutdown occurnce
58- data link fault
58- power data link fault


A friend said to dead head the Heui pump with a pressure gauge and look for 4000-5000 psi to determine if pump is good. Other directions are to test the ECM or replace wiring harnesses.

Anyone here having any other guidance.

Thanks in advance y'all.

I would just tee into the pressure line at the head instead of deadheading. It would probably be worth having someone with cat et hook up and compare the pressure you get with what the ecm is seeing thru the iap sensor

Have you ever seen any sign of rodents in or around the truck?

Before you start throwing parts at it, thoroughly check the wiring harnesses.

Get a proper scan tool hooked to the truck, most of those codes could be inactive.

Sounds more like an electrical problem you shouldn't need the complete pump just the coil on the iapcv if anything. I would recommend you get ET hooked to it and diagnosed before monkeying with it. Shouldn't cost much.

Just wanted to update the thread and say thank you for everyone who has commented.

Based on comments here from MobilTech and others, I went searching for electrical problems.

Replaced the alternator (suddenly quit working) and speed sensor on transmission. Then began disconnecting wiring harnesses and looking for burn/rubbed/corrosion etc.


Unhooked the ECM looking for corrosion, found none and plugged it back in. Truck now works flawlessly.

Except when you hit a bump and the check trans light blinks (like its got a bad connection)

My amateur diagnosis is that we have a broken wire in the harness from ECM to TCM or transmission.

Our current dilema is do we:
1. replace the entire wiring harness ($550 from Freightliner) -several wires in this truck look bad shape
2. find and fix single broken wire(s)
3. Junk/trade truck and get something more reliable

Not expecting answers here on the forum to my last question as I realize it is ambiguous and without relevant information like mileage, engine hours, maintenance intervals etc., but feel free to throw out your opinion. I'm tired of thinking and happy to listen.

Happy 4th Everybody.

I'd take a look at the pins in the plugs. It is possible for them to spread over time and lose contact.

Forgot to update this forum way back but anyways here it is.

Green plug on fuse box had two bad connections. One from TCM, other was blower for cab. New plug and back in business.

Thanks