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Old 08-31-2016, 06:38 PM   #11
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 5,070
Year: 1991
Coachwork: Carpenter
Chassis: International S3800
Engine: DT360
Rated Cap: 7 Row Handicap
Quote:
Originally Posted by family wagon View Post
I played briefly with a Chinese heavy truck scan tool but sent it back because it turned out the thing was pirate-ware through and through. It was a clone of the Nexiq USB Link and included DVDs with cracked installers for the diagnostic software for just about all the names in heavy trucking (Cummins, CAT, Allison, Bendix, Perkins, and so on). I wish this stuff could be had legitimately for even $500-ish instead of the thousand(s) the real deal currently sells for. A word of warning to anybody who might decide to seek out the Chinese pirated versions: Set it up on a dedicated computer and keep it away from your good computer. Cracked software is often also virus-laden.

As for legit heavy truck scan tools: there are some all-in-one setups priced at $1000-$2000. There are also computer link cables like the Nexiq USB Link I mentioned earlier. I think I found it about $600, but then there's hundreds to thousand-and-some dollars of additional cost for the software from the various manufacturers. It gets spendy fast.

Right, J1708 is just physical (RS-485 and a round connector more or less). SAE J1587 defines the protocol on top. I haven't coughed up the money to buy a copy of that spec yet. Though I did acquire a copy of the American Trucking Associations Technology & Maintenance Council RP1210 spec.. I found a legit but dated CD version of the TMC manual containing RP1210 from maybe year 2010 on Amazon for about $30. I hoped to build something similar to the Nexiq data link hardware but that project hasn't gone anywhere.
run the software easily in a Virtual machine which is NATTED and FIREWALLED against the original bridge network of your laptop...

build the VM, take an IMAGE of the VM so if you get a virus you just reload the image... easy cheesey and safe..

-Christopher
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Old 09-03-2016, 10:57 PM   #12
Almost There
 
Join Date: Sep 2015
Location: Salt Lake City, Ut
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Year: 98
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Chassis: D
Engine: 7.2L turbo Cat C7 3126
Rated Cap: 84
I have a new update. I was able to create a cable connecting my computer to the ECM. I found a J1708 6 pin connector which I wired to a RS485-to-RS232 adapter. I connected that to a USB-to-RS232 adapter. I installed some VISA drivers, then wrote a labview program where I could read the raw ECM data. I found a copy of the SAE-J1587 protocol, which allowed me to decode the data. But I'm not sure how closely Caterpillar followed the protocol, they very easily could have made proprietary changes. Anyways, here is what the raw data looks like:

82BF 0400 BB80 5B08 BE00 005C 0054 00AF 82BF 0400 BB80 0201 5540 B700 00B8 0000 7980 5B08 BE00 005C 0054 00AF 82BF 0400 BB80 5B08 BE00 005C 0054 00AF 82BF 0400 BB80 0201 5540 B700 00B8 0000 7980 5B08 BE00 005C 0054 00AF 8069 496E 49A4 0000 A8FD 00CE ...

Its a little easier to read in decimal:

128 91 8 190 0 0 92 0 84 0 175 130 191 4 0 187 128 2 1 85 64 183 0 0 184 0 0 121 128 91 8 190 0 0 92 0 84 0 175 130 191 4 0 187 128 91 8 190 0 0 92 0 84 0 175 130 191 4 0 187 128 2 1 85 64 183 0 0 184 0 0 121 128 91 8 190 0 0 92 0 84 0 175 128 105 73 110 73 164 0 0 168 253 0 206

MID = The device transmitting (128 = Engine, 130 = Transmission)
PID = The part of the device sending data. PIDs 0-127 and 256-383 send one character of data. PIDs 128-191 and 384-447 send 2 data characters
Then there is a checksum

so 128 91 8 190 0 0 92 0 84 0 175 reads:
Engine [128] Percent Accelerator Pedal Position [91] 8% [8],
Engine Speed [190] 0RMP [0 0], Road Speed [84] 0MPH and [175] is the checksum.

At least this is my best guess so far. I am going to write another program to better parse the raw data and present it in an easier to read format.
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Old 09-03-2016, 11:05 PM   #13
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So the ECM is not burned out, that makes me happy But the bus still won't start. I bought and installed a new fuel filter and a new water separator/fuel filter. I filled them up with diesel using a pvc plug in the center hole so all the diesel entered the outer holes. Bus still wouldn't start.
There is a hand pump next to the fuel filter.

Is there an air release valve or something I need to do in conjunction with using the hand pump?
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Old 09-03-2016, 11:12 PM   #14
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Nice! You must have worked harder than I did to track down J1587. I searched online a bit and even went asking at the University of Utah thinking surely that's the sort of thing they'd have tucked away in the campus library someplace.. no luck.

FYI in that dump you broke apart, there's a 92 0 in the middle that you didn't list the meaning of. Now I'm curious about it!

Also, in case it's useful, I have an FTDI USB-RS485-WE-1800-BT cable you could borrow. I haven't spent any time thinking about how to hack it into the open collector mode that J1708 wants to see.. maybe I have an open collector buffer chip at work that could be bread-boarded.

Is the ECM supposed to routinely broadcast trouble codes the way it does those other codes, or do you have to inject a command into the J1708 bus to query for them?
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Old 09-04-2016, 09:18 AM   #15
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Gawd I love all mechanical engines!
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Old 09-06-2016, 04:18 PM   #16
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Join Date: May 2014
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Quote:
Originally Posted by family wagon View Post
Nice! You must have worked harder than I did to track down J1587. I searched online a bit and even went asking at the University of Utah thinking surely that's the sort of thing they'd have tucked away in the campus library someplace.. no luck.

FYI in that dump you broke apart, there's a 92 0 in the middle that you didn't list the meaning of. Now I'm curious about it!

Also, in case it's useful, I have an FTDI USB-RS485-WE-1800-BT cable you could borrow. I haven't spent any time thinking about how to hack it into the open collector mode that J1708 wants to see.. maybe I have an open collector buffer chip at work that could be bread-boarded.

Is the ECM supposed to routinely broadcast trouble codes the way it does those other codes, or do you have to inject a command into the J1708 bus to query for them?
You have to inject a command. The data that's being showed is just updates that indicate what's currently going on to keep the other modules informed. When the code happens it will send out an indication that something happened to the other modules but until it's requested or a new code appears, it won't reappear.

You guys do know that you can get these little light boxes that will attach to the data port and flash your codes to you. The main reason for the scan tool is for the data monitoring and logging, stuff most of you won't need.

PS, the pirated stuff is anywhere 2-5 years out of date. It's useful for old stuff like the busses on here but pretty limited if you're trying to use it for newer equipment.
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Old 09-06-2016, 04:31 PM   #17
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Join Date: May 2009
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you do have to inject a command.. usually you pull one of the data lines low for a specified period of time which will put the line into RX mode then you can send the command.. at least thats how Most of the OBD stuff ive worked with handles it. some PCM's didnt follow the spec correctly and would simply go into RX if you sent any character on the line such as 3 NULLS if I remember right and then the command to retrieve trouble codes followed by its checksum or LRC.. i was thinking they used LRC in this but its been years I cant remember.

-Christopher
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Old 09-06-2016, 05:45 PM   #18
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Quote:
Originally Posted by gobygoby View Post
So the ECM is not burned out, that makes me happy But the bus still won't start. I bought and installed a new fuel filter and a new water separator/fuel filter. I filled them up with diesel using a pvc plug in the center hole so all the diesel entered the outer holes. Bus still wouldn't start.
There is a hand pump next to the fuel filter.

Is there an air release valve or something I need to do in conjunction with using the hand pump?
If you have a hand pump you should be good to go but you need to break the seal on each injection line.
If you have help you can use the starter and start breaking lines loose at the injectors in firing order until you get fuel and pay attention to which injector it starts to hit on cause that could Meen a bad injector.
If you don't have help you can break each injector line loose separately and pump your arm away until you prove fuel at each injector and if all proves fuel and still doesn't start then I would say an injector seal is bad and without it even trying to catch and run rough then I would think it is in the top three of the firing order so you might be able to swap around the back ones in the firing order one at a time and see if it try to catch?
A lot of parts changing and priming but it would/could save money with only buying the parts you do need and not just buying and changing stuff you don't?
I wouldn't know where to start with anything computer Ya'll have been talking about? I am hands on and have worked on tractors/trucks since I was a kid? I say a bad injector or injector o-ring sucking air?
Good luck
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Old 09-07-2016, 08:13 AM   #19
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Join Date: Sep 2015
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Chassis: D
Engine: 7.2L turbo Cat C7 3126
Rated Cap: 84
I believe you can send a command to read faults, but they are also rebroadcast automatically at least every 15 seconds. The fault codes are prefaced with a PID between 194 and 196. I captured 20 seconds of data and then searched for those numbers. After not finding them, I moved my search away from the electrical portion of ignition and focused on the mechanical portion.

That lead me to think it a was a faulty fuel pressure regulator. I took note of the fuel levels in both fuel filters and cranked the engine for a few seconds. Then I rechecked the fuel levels and they were a little lower than before with extra air on top. I then heated up the regulator with a heat gun and repeated the test. This time the fuel filters were half empty after cranking.

So I went to the Cat dealership yesterday and bought a new regulator ($36). Getting the old regulator off was challenging because it is on the very back side of the engine and the rear seat curve gets in the way of the wrench. The new regulator had slightly different threads than then old, so I had to reuse the old valve housing (part# 124-3545). I drilled out the tiny hole in the valve housing and used it as an adapter to install the new one.

After lots of pumping to get the remaining air out, the engine started!!!

Special thanks to family_wagon for stopping by and helping out, and thank you to everyone helping out here on the forum
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Old 09-07-2016, 09:06 AM   #20
Bus Nut
 
Join Date: May 2014
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Engine: 6.9 International
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You probably just needed to pump the remaining air out. The lift pump on these are mechanical on the backside of the injection pump. You most likely lost prime through the filters and fuel lines leading up to the pump which is why it wouldn't start.

If I remember right, the regulator has a small hole in it to bleed off air and a spring loaded valve to control fuel pressure.

As far as cracking lines to release air, there are no injection lines to crack on a heui engine.

Mechanically, all you have to do is provide fuel to the lift pump, and oil pressure to the injection pump, and it should light off. If it doesn't, then you check the computer.
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