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Jeremy, Certified Truck/Bus Technician
Category: Medium and Heavy Trucks
Satisfied Customers: 3304
Experience:  ASE Med/HD Truck Technician, NATEF Diesel Engines and Electrical/Electronics Technician, EPA 608/609 HVAC Certified, Steering/Suspension and ABS/Brakes Technician
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I have a 2007 intl. 4300 with an allison 220 rds, it goes to

Customer Question

hi, I have a 2007 intl. 4300 with an allison 220 rds, it goes to failsafe after a couple of seconds any time a forward gear is selected and check trans light comes on.I have pulled a###-##-####31 code, having a hard time finding code description
JA: What's the make/model/year of your truck? Engine type?
Customer: dt 466
JA: Anything else you want the truck mechanic to know before I connect you?
Customer: no
Submitted: 6 months ago.
Category: Medium and Heavy Trucks
Expert:  Jeremy replied 6 months ago.

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On the push button display for the transmission, what codes do you have there?


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Expert:  Jeremy replied 6 months ago.

The reason I ask for the code on the Allison is becasue the code you provided is J1939 communication error, which is a fault in the harness or in the module. I'm hoping the Allison code will break the issue down more, otherwise this will need the old school check of the full harness to the transmission. J1939 codes are really hard to diagnose without going through the harness pin by pin and inch by inch.

Customer: replied 6 months ago.
no buttons, just a stick,no display, the trans. codes dont come up on the instrument cluster, i had to pull with a code reader
Expert:  Jeremy replied 6 months ago.

A code reader works as well.

If that is the only code, then all that you can do is go through the transmission harness and see which wire is shorting on you. Start at he tee since that is the most common spot. It is where the tee is for the TCU and the harness that goes into the transmission then to the engine. That is where 90% of the rub throughs occur.

Customer: replied 6 months ago.
Is there a specific code description for this code? Is this an inter-module communication code? I retrieved it from the transmission. I retrieved the other codes from the engine.
Expert:  Jeremy replied 6 months ago.

The code is J1939 communication error - TCU - nothing follows

That is all that it offers. There is no other information or a diagnostic tree for it. Allison doesn't even show one. I was just on there trying to find something.

Customer: replied 6 months ago.
ok, do you have any illustrations of where this "t" is or what it looks like?I gather it's in the main tcu to ecu harness where there's a breakout to the trans thru-case connector?thanks
Expert:  Jeremy replied 6 months ago.

Follow the harness out of the TCM. Where it splits into all the different directions, that is the Tee. That is where the rubbing happens becasue it rests on the top of the transmisison and just rubs around. That is the area to check.

The other spot to check is where is plugs into the transmission itself. Unplug that connector (I would check here first honestly) and see if there is oil in that connector. If so, clean it with electrical contact cleaner spray (like 9.99 from auto parts store) and let it sit a few minutes. Then spray it again just to be sure. It eats the oikl and corrosion without harming the electrical. Then put back together and see if it clears. If not and you had oil there, then replace the internal harness for that is where you are getting the error from most likely because that harness is pushing oil and grounding out your connection. I see that a lot with solenoid issues on the harnesses on the Allisons.

Customer: replied 6 months ago.
Ill check mon. and get back,ty.
Expert:  Jeremy replied 6 months ago.

Have a good weekend!

Customer: replied 6 months ago.
hi, no defects in harness or connector that i can see,is this dtc ecm or tcm generated?Is it possible that Im simply unable to pull the codes from the tcm and the dtc gathered is similar to an obd p0700 code that simply says that a dtc exists in the tcm?I used an otc hd truck code reader and am unsure whether i should pursue a more capable unit or software?Im not really into shelling out for the allison doc setup, but is it necessary?if not, do you have any recommendations for such?I'm a veteran auto/ light truck obd1 and 2 tech. and am hesitant to pursue other avenues without knowing whether there is any useful codes in the tcm per my experience.your reply appreciated, would like to make a solid move in this direction soon if you have any suggestion on this or if you think this is wothwhile.thanks
Expert:  Jeremy replied 6 months ago.

I suggest JPro or PF-Diagnose. PF-Diagnose is for cars and trucks to pull codes using a Nexiq USB Link adapter. You can run regens with it as well. If you are doing Allisons a lot, then the DOC software is good. For just one vehicle, not worth it at all. The only benefit is the programming.

The codes are generated by the ESC on the truck. The ECM and the TCM send faults to the ESC and the ESC is what will give the code. It is the central gateway on the truck that the scan tools connect to.

It's possible to have a weird code generated. Allison's code for some of the smallest issues. Voltage low from a bad fuse is an example of a code that will throw. Disconnecting the batteries will throw a code. Hot temp or cold temp will throw a code. Allisons are weird like that, but that is where a scanner is needed because sometimes the codes are there and won't clear when the issue is resolved as well. I've ran into that many times on the Allisons. Especially after a Allison shop gets it changes the parameter to not allow a code reset on its own. I change the parameter when I see those trucks with it for it causes un-needed issues except for shop revenue.

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