CAT 31260 Engine Diagnostic

[daniauction]

Hello hello everyone
I have a mechanics that bring his CAT communication adapter (see attached pictures) to diagnose a fault it has but after an hour or so he could not connect to read the engine .Also is there any adapter for the truck connector to this system.

THANK YOU

 

[Skyhawk13205]

People have reported bad CAN bus resistors, also people have reported having 24volts shorted to the databus. I would suggest checking voltage on the 1939 and 1708 buss and verifiying you have only a high and low signal not a system voltage. Then check the can buss resistance. I would then try to interrogate other ECUs. If you can get a readout from the transmission ECU or the ABS ECU that should tell you the databus is intact. If the databus is intact you need to check power and signal from the engine ECU. If you have a truck with a bypass power harness for the engine ECU it has probably failed. The bypass has a shielded connector that starts to cut into the wires and either causes the harness to short or causes no power to ecu.

My truck has a bypass harness that spliced into the power of the ECU that caused a lot of engine problems such as intermittent cutout and no start, later 3126 trucks have an updated harness that removes the bypass and splices power into the ecm harness further up the run near the PDP.

 

[Ronmar]

And this was pretty early in Cats ECU experience. Have had quite a few units who’s internal memory power source has failed(bricks the ECU)…

 

[GeneralDisorder]

Internal battery won't cause a coms issue. It's either the wiring, the termination resistors, or the ECM is just not having it. The 3126 ECM is a real piece of $hit to communicate with. Often early ones will require a dozen or more reflash attempts. The technology on them was new for the era and now they are 25 year old garbage with aging components that fail if you sneeze on it wrong.

Tell your CAT guy to get a 70 pin chassis harness adapter and just jack directly into them computer on the side of the engine. Or pull it and send it to me. I can read the codes it has also.

 

[daniauction]

The guy check every pin from the ECM on the engine to the connector inside the cabin (I don't remember the name , see Picture) and it was good.
Thank You

 

[GeneralDisorder]

Most likely it's a combination of the ECM being early and cantankerous, and the truck's wiring being decades old, and the alignment of the moon and the stars. The majority of the 3126 trucks I've flashed simply WOULD NOT do it through the harness and had to be flashed with a 70 pin bench flash adapter.

You're CAT guy is ill-equipped and/or insufficiently trained/experienced with this ECM and probably has zero experience with Army junk and FMTV's in particular. Being it runs and all, it's got "good enough" wiring on the chassis side for that, but two-way communications is possibly asking more than the combination can provide. I'm surprised it won't at least give you live data and codes but I don't use the CAT communications adapters so IDK for sure if his setup is correct. I use the Dearborn Protocol Adapters, and the SWICE wireless adapter - which contrary to most of my experience with Army supplied diagnostics, actually works better most of the time even being wireless. But the most recent black SWICE kits are very rare and difficult to source. I've only ever seen three come up for sale and two of them I purchased.

At the end of the day - 25 year old wiring and computer designed to speak with Windows 95. Yeah it's going to be a rough one to pull that thing kicking and screaming into coms with a modern hookup. Early. Primitive. Unreliable, Expensive..... yep checks all the boxes for Army "Technology". Worked great in a lab so ship it to the field and let the Joe's break it! We'll clean up the pieces on the back end - only a few billion $$ extra that way.......

 

[daniauction]

Most likely it's a combination of the ECM being early and cantankerous, and the truck's wiring being decades old, and the alignment of the moon and the stars. The majority of the 3126 trucks I've flashed simply WOULD NOT do it through the harness and had to be flashed with a 70 pin bench flash adapter.

You're CAT guy is ill-equipped and/or insufficiently trained/experienced with this ECM and probably has zero experience with Army junk and FMTV's in particular. Being it runs and all, it's got "good enough" wiring on the chassis side for that, but two-way communications is possibly asking more than the combination can provide. I'm surprised it won't at least give you live data and codes but I don't use the CAT communications adapters so IDK for sure if his setup is correct. I use the Dearborn Protocol Adapters, and the SWICE wireless adapter - which contrary to most of my experience with Army supplied diagnostics, actually works better most of the time even being wireless. But the most recent black SWICE kits are very rare and difficult to source. I've only ever seen three come up for sale and two of them I purchased.

At the end of the day - 25 year old wiring and computer designed to speak with Windows 95. Yeah it's going to be a rough one to pull that thing kicking and screaming into coms with a modern hookup. Early. Primitive. Unreliable, Expensive..... yep checks all the boxes for Army "Technology". Worked great in a lab so ship it to the field and let the Joe's break it! We'll clean up the pieces on the back end - only a few billion $$ extra that way.......

So what is the correct way to find the engine fault?
And for what you describe this truck are not reliable at all to go around the world.
This is a little scary since I have plans to convert it into an expedition truck.
THANK YOU @GeneralDisorder

 

[GeneralDisorder]

Well - reliability is what YOU make it. If you need reliability then you need to add redundancy and bring the diagnostics in-house so-to-speak. That is you need spare electronics, and the ability to diagnose, test, and swap all such components in the field without ANY outside assistance. Laptop and protocol adapter with the manufacturer specific software for each system, plus test equipment like a 24v capable test light with loads, front-probe and back-probe kit, DMM, and a handheld oscilloscope would be an absolute minimum along with all the up-to-date digital manuals and commercial part cross-reference (Fed-Log).

That means one or even two extra engine computers, and the same for the transmission computer, the ABS computer, the starter, and any other electronic module that will be very expensive or impossible to source in Europe. And a list of contingencies - IE what to do if/when each major component fails. How to bypass the trash-can relay, how to manage battery charge in case of alternator failure, and simplified test procedures for specific systems.

If you are going out with these trucks and you don't have a Motorpool contact truck/wrecker recovery team following you into battle (that was my actual job in the Army) then you have to be ALL THAT yourself. Or as much as is reasonably possible.

If that's not what you were looking for then I would suggest a brand new truck with a warranty and a Platinum level towing/recovery package that works anywhere you are planning to go. You break down in an FMTV in some third-world back water - it's just you and the machine. No one will know all the proclivities of these trucks unless you happen to end up in Afghanistan or Ukraine where we seem to leave them laying around.

All that is to say I don't believe you will find ANY 25 year old used vehicle that doesn't have at least some of these same problems. The difference is that most of the those you will NOT find the schematics, repair, and software availibility like we have for the FMTV's. Because these were built to be serviced and repaired and the Army demanded ownership over the repair information. There's no significant intellectual property barriers to the FMTV and at least for the A1R's you can find trucks as new as 2010 or so - while anything in the civilian world that is this new will have much of the necessary repair information hidden behind IP or pay-walled at the very least. And then you have some manufacturer that is ultimately only interested in selling you a new one. With these trucks you remove most of that and I personally would rather just have myself to blame rather than be an old man shaking my fist at the cloud because some manufactuter is holding me hostage.

 

[Ronmar]

yea you really need to bring the control unit comms in-house at the very least with a laptop and interface and work out how to talk to these things on your own... I wouldn't necessarily have a spare of everything along, but I would have a shipping plan to have parts you have stored shipped to you for foreign travel...

 

[GeneralDisorder]

yea you really need to bring the control unit comms in-house at the very least with a laptop and interface and work out how to talk to these things on your own... I wouldn't necessarily have a spare of everything along, but I would have a shipping plan to have parts you have stored shipped to you for foreign travel...

One of our Canadian FMTV enthusiasts just got stranded 400km out in the forest of Quebec and had to walk a LONG way to find a farmer to tow his 3126 out to a main road where he could get a proper tow truck to the nearest civilized city with a diesel shop. Dead 3126 ECM. Several weeks down and just the ECM repair (not even a new one, which is ~$6500 plus programming from CAT) was $2,000 and that's not towing, or diagnostic/programming labor, etc. And he's currently in a holding pattern waiting for the repair - which I can almost guarantee will be a boondoggle since his original is dead and there's probably no hope of them having the ability to correctly program the ECM on the first or second attempt since the original unit is dead and likely the programming is lost and he obviously went out with no spare. This will easy cost him $10k, weeks of downtime and frustration which could have been avoided if he carried a pre-cloned spare module.

 

[Ronmar]

Or had a programmed spare at home ready to be shipped...

 

[Gcelevator]

Very good tread to follow and learn.

 

[daniauction]

For now, my plans are to go from Miami to Canada, cross Canada from east to west to Alaska, and from Alaska head south to Ushuaia (Argentina). As FMTV experts, do you think that if I manage to make all the necessary repairs and get the truck in optimal condition and carry spare parts, I can do it? Or would it be better to get an old Mercedes-Benz with a manual transmission, which has spare parts available almost everywhere in the world?


Sent from my iPhone using Tapatalk

 

[daniauction]

I really appreciate your honest opinion.


Sent from my iPhone using Tapatalk

 

[swiss]

For now, my plans are to go from Miami to Canada, cross Canada from east to west to Alaska, and from Alaska head south to Ushuaia (Argentina). As FMTV experts, do you think that if I manage to make all the necessary repairs and get the truck in optimal condition and carry spare parts, I can do it? Or would it be better to get an old Mercedes-Benz with a manual transmission, which has spare parts available almost everywhere in the world?


Sent from my iPhone using Tapatalk

Where are you going to find a better support system then the steel soldiers family? I would vote lmtv.

 

[daniauction]

Most likely it's a combination of the ECM being early and cantankerous, and the truck's wiring being decades old, and the alignment of the moon and the stars. The majority of the 3126 trucks I've flashed simply WOULD NOT do it through the harness and had to be flashed with a 70 pin bench flash adapter.

You're CAT guy is ill-equipped and/or insufficiently trained/experienced with this ECM and probably has zero experience with Army junk and FMTV's in particular. Being it runs and all, it's got "good enough" wiring on the chassis side for that, but two-way communications is possibly asking more than the combination can provide. I'm surprised it won't at least give you live data and codes but I don't use the CAT communications adapters so IDK for sure if his setup is correct. I use the Dearborn Protocol Adapters, and the SWICE wireless adapter - which contrary to most of my experience with Army supplied diagnostics, actually works better most of the time even being wireless. But the most recent black SWICE kits are very rare and difficult to source. I've only ever seen three come up for sale and two of them I purchased.

At the end of the day - 25 year old wiring and computer designed to speak with Windows 95. Yeah it's going to be a rough one to pull that thing kicking and screaming into coms with a modern hookup. Early. Primitive. Unreliable, Expensive..... yep checks all the boxes for Army "Technology". Worked great in a lab so ship it to the field and let the Joe's break it! We'll clean up the pieces on the back end - only a few billion $$ extra that way.......

Well - reliability is what YOU make it. If you need reliability then you need to add redundancy and bring the diagnostics in-house so-to-speak. That is you need spare electronics, and the ability to diagnose, test, and swap all such components in the field without ANY outside assistance. Laptop and protocol adapter with the manufacturer specific software for each system, plus test equipment like a 24v capable test light with loads, front-probe and back-probe kit, DMM, and a handheld oscilloscope would be an absolute minimum along with all the up-to-date digital manuals and commercial part cross-reference (Fed-Log).

That means one or even two extra engine computers, and the same for the transmission computer, the ABS computer, the starter, and any other electronic module that will be very expensive or impossible to source in Europe. And a list of contingencies - IE what to do if/when each major component fails. How to bypass the trash-can relay, how to manage battery charge in case of alternator failure, and simplified test procedures for specific systems.

If you are going out with these trucks and you don't have a Motorpool contact truck/wrecker recovery team following you into battle (that was my actual job in the Army) then you have to be ALL THAT yourself. Or as much as is reasonably possible.

If that's not what you were looking for then I would suggest a brand new truck with a warranty and a Platinum level towing/recovery package that works anywhere you are planning to go. You break down in an FMTV in some third-world back water - it's just you and the machine. No one will know all the proclivities of these trucks unless you happen to end up in Afghanistan or Ukraine where we seem to leave them laying around.

All that is to say I don't believe you will find ANY 25 year old used vehicle that doesn't have at least some of these same problems. The difference is that most of the those you will NOT find the schematics, repair, and software availibility like we have for the FMTV's. Because these were built to be serviced and repaired and the Army demanded ownership over the repair information. There's no significant intellectual property barriers to the FMTV and at least for the A1R's you can find trucks as new as 2010 or so - while anything in the civilian world that is this new will have much of the necessary repair information hidden behind IP or pay-walled at the very least. And then you have some manufacturer that is ultimately only interested in selling you a new one. With these trucks you remove most of that and I personally would rather just have myself to blame rather than be an old man shaking my fist at the cloud because some manufactuter is holding me hostage.

Hello guys
I want to make the truck redundancy as much as posible.
I just saw an ad on Marketplace for this device( picture) he ask $400 and said have a mil Cat ET . Should it work with the CAT 3126? What else do I need?
THANK YOU

 

[GeneralDisorder]

DPA-4 for $400 isn't a terrible deal. It will require a windows laptop. I think I paid $220 for mine on ebay so it's not the *best* deal but a new DPA-5 Pro is like $800 so it's still half the price of new. Dealers choice if you need it now or want to wait.

 

[ckouba]

As of a while ago, you could get a full set of connectors for ~$500. Look for:

Adapter Kit, ICE Test Dearborn Protocol, Data Bus Kit, Probe Set NOS With Disc's

Edit:

Good grief, they've gotten expensive:

FULL ADAPTER KIT ICE TEST, PN 13608012,MTR;4QTAO S/N PIF0615, Data Bus Kit, | eBay

6625-01-516-6825 NOS Adapter Kit; Test ICE IFTE U.S. Army Aviation 13608012 18876-13608012 103926-1, 13608010-2 13580831, 13580836,13580844,1358045,13608011,12258786, 12258784. 103926-1, 12258784, 12258786, 1358045, 13580836, 13580844, 13608010-2 13580831, 13608011, 13608012, 18876-13608012...

www.ebay.com

I got mine for ~$520, plus a specific laptop for the truck with appropriate ports for the kit. Very worthwhile investment. Keep poking around and you may find a better deal. I bet they're out there.

 

[GeneralDisorder]

Those will work too, The STE-ICE kit is OLD but has all the stuff for extended systems testing and the old Serial DPA-III - which works fine you just need a laptop with an RS-232 hardware serial com port.

I have the software to make those work as the worlds largest and most inconvenient digital multi-meter on earth. 30 feet of cable, a laptop, and an interconnect box the size of your head and you too can look like the Amish trying to change a wagon wheel on the freeway. Hilarious!

And yeah some people think those are worth a mint. Mine collects dust on the shelf 99.995% of the time but they were $250 and everyone had stacks of them they could barely give away. Now you have scalpers waiting for some n00b to come along and pay a crazy price for one.

 

[DeMilitarized]

For now, my plans are to go from Miami to Canada, cross Canada from east to west to Alaska, and from Alaska head south to Ushuaia (Argentina). As FMTV experts, do you think that if I manage to make all the necessary repairs and get the truck in optimal condition and carry spare parts, I can do it? Or would it be better to get an old Mercedes-Benz with a manual transmission, which has spare parts available almost everywhere in the world?


Sent from my iPhone using Tapatalk

You can do it but get the NEWEST and best mechanical condition truck you can. Late model a1 or a1r and start driving it everywhere and fix every last thing that starts to go wrong. Stuff will fail left and right then it will all start to smooth out after about 5k miles of driving and you will learn the quirks and issues with the truck. Then address them. Start small and work big.