Please help me. 1999 Thomas International 3800 DT466e

Grimreaper86

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Joined
Feb 25, 2025
Posts
7
Location
Indianapolis
I have a 1999 Thomas International 3800 with a DT466E engine. It ran when I got it. I parked it in my drive way. Started it twice after that. The second time I started it; I moved it a little and I played with some of the light switches and the stop sign thing because I had never done that. After that, my batteries died because I left one of those switches on for thawing your wing mirror or something and I didn't come back to it for like 3 days. It drained them so much I couldn't charge them. I went and bought new batteries. Since then, I have not been able to get it to run. It will crank, but it won't start without starter fluid and it won't run at all without it. It's obviously not getting fuel and I think it's electrical related and so does the most recent mobile mechanic I had out here. Here is what I've done myself. Replaced an ICP sensor, replaced the ECM, replaced fuel filter, replaced fuel starter pump, replaced fuel primer pump, ICP valve, and replaced the crankshaft sensor. The mechanic who said he thought it was electrical normally works on semi's...his boss said he thought there should be a fuse box on the fire wall on the drivers side that should have some sort of 80 amp fuel filter fuse but that fuse box isn't there in this bus. Probably because it's not a semi. I only can find two area for fuses. One right next to the drivers seat where all the light and fan switches are and the other on the front dash sort of to the right of center a little. Neither of those locations looks like it has what this guy is talking about. He said his shop could figure it out for sure but that means towing this bus there and just towing it there is going to be $600...all for what is likely a damn fuse we just can't find. I'll go that route if I have to but I'd really just rather try to fix it myself if I can find this fuse that might be causing this issue. Does anyone have any incite or ideas that on where I might find the culprit of my issue? Any help would be appreciated. Thanks.
 
First and foremost, stop using starting fluid on your motor! It can be damaged from too much starting fluid!
Use plain ol silicone spray instead, not as volatile as starting fluid.

secondly, look in the battery compartment for a pigtailed fuse, one that connects to the battery. this is a common place for the ECM and TCM fuse to be. Don't just check the fuse, fuse holder are prone to overheating and breaking the wire internally.

Thirdly, stop chasing/replacing part, unless your wealthy that is...have you invested in a Nexiq clone and downloaded the Servicemax software? This is a must do if you own a bus that your gonna be fixing. Without it all your doing is guessing...wildly...

Don't spend $600 bucks on towing, buy the Nexiq clone and D\l the free servicemaxx software!
 
I'll get this thing: Diesel Universal Heavy Duty Truck Excavator Diagnostic Scanner Tool for Nexiq

But I did have a mechanic with a scanner tool come by once and all the info he gave me said something to the affect of communication issues with the ECM/ICP sensor....both of which have been replaced at this point...so I don't believe having a scanner will narrow down the issue. I will try to take a better look at the fuse thing in the battery compartment but last I looked it appeared to be in good shape (One of those little yellow ones). Perhaps I'll buy a light tester things and test it that way. The wiring itself looked fine but maybe if I take the fuse out and look at the fuse receptacle closer I will find an issue that wasn't immediately obvious.
 
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Have you pulled any codes from the ecm by using the momentary button by the deutsch diagnostic connector?
Yes,

It gave me all sorts of codes. I couldn't find out what all of them mean but I can give you a list as of what they were in the order I got them.

124
335
124
122
313
323 or 123 (it's looks like I wrote a 3 with a 1 through it)
626
231
513
514

That's what I got when I tried that.
 
You really could use the diagnostic manual EGES-175-1 but I can't find it here but it's on Scribd.com for download. See THIS THREAD post #10 and 17 for code info. 335 could be an issue and injector ground short for 513/514 would be another. 626 is when you changed the battery. The discrepancy in the 3/1 could be if another light flashed twice when going from active to inactive codes.
 
After re-reading your posts I too tend to agree your issue is electrical. what is the one thing you did when all this started? Replaced the batteries you said....

Well then start from the beginning, recheck your power and grounds, also check your ECU fuse pigtail.

You need to visually and physically inspect your ground from the battery to the frame, especially on the frame! open it up, clean it up and re-secure!

You ECU might also be grounded to a "Stud" on the engine block. open and clean that ground too!

Check for clean consistent power to the ECU.
I believe you stated you replaced the ECU already?

Also, download the doc from this link. You will get the EGED-185-1 file which will tell you all about the trouble codes and also has a wiring map for you to follow.


PDFCoffee does not charge or make you sign up to download. I have gotten numerous manuals from that site.

Once you check your power feeds and grounds, give us some feedback on your progress.
 
After re-reading your posts I too tend to agree your issue is electrical. what is the one thing you did when all this started? Replaced the batteries you said....

Well then start from the beginning, recheck your power and grounds, also check your ECU fuse pigtail.

You need to visually and physically inspect your ground from the battery to the frame, especially on the frame! open it up, clean it up and re-secure!

You ECU might also be grounded to a "Stud" on the engine block. open and clean that ground too!

Check for clean consistent power to the ECU.
I believe you stated you replaced the ECU already?

Also, download the doc from this link. You will get the EGED-185-1 file which will tell you all about the trouble codes and also has a wiring map for you to follow.


PDFCoffee does not charge or make you sign up to download. I have gotten numerous manuals from that site.

Once you check your power feeds and grounds, give us some feedback on your progress.
When you say ECU do you mean the ECM?
 
After re-reading your posts I too tend to agree your issue is electrical. what is the one thing you did when all this started? Replaced the batteries you said....

Well then start from the beginning, recheck your power and grounds, also check your ECU fuse pigtail.

You need to visually and physically inspect your ground from the battery to the frame, especially on the frame! open it up, clean it up and re-secure!

You ECU might also be grounded to a "Stud" on the engine block. open and clean that ground too!

Check for clean consistent power to the ECU.
I believe you stated you replaced the ECU already?

Also, download the doc from this link. You will get the EGED-185-1 file which will tell you all about the trouble codes and also has a wiring map for you to follow.


PDFCoffee does not charge or make you sign up to download. I have gotten numerous manuals from that site.

Once you check your power feeds and grounds, give us some feedback on your progress.
Looked at some diagrams and such and despite it being night time right now I got a flashlight and did some looking. Found the pig tail. See the 40 amp fuse. Looks clean so does the wiring and connector to it. Found the ground going from the battery bank to the frame. The cord itself looks solid but the connection on the frame is covered in a decent bit of mud. I'll clean it and reattach it tomorrow and see if that helps. I don't see a ground directly on the ECM but one of the diagrams you guys linked shows an ECM relay box and mentioned a stud connected to a relay. I haven't really looked for that closely yet but I'll take a better look tomorrow when I clean the ground cable. BamaBus mentioned "335 could be an issue and injector ground short for 513/514 would be another." I'll see if I can check the wiring harness for faults. I'd find that surprising that a short would develop in that span of time but who knows. It looks like it would be a wiring harness issue or maybe a faulty fuel injector.
 
Looked at some diagrams and such and despite it being night time right now I got a flashlight and did some looking. Found the pig tail. See the 40 amp fuse. Looks clean so does the wiring and connector to it. Found the ground going from the battery bank to the frame. The cord itself looks solid but the connection on the frame is covered in a decent bit of mud. I'll clean it and reattach it tomorrow and see if that helps. I don't see a ground directly on the ECM but one of the diagrams you guys linked shows an ECM relay box and mentioned a stud connected to a relay. I haven't really looked for that closely yet but I'll take a better look tomorrow when I clean the ground cable. BamaBus mentioned "335 could be an issue and injector ground short for 513/514 would be another." I'll see if I can check the wiring harness for faults. I'd find that surprising that a short would develop in that span of time but who knows. It looks like it would be a wiring harness issue or maybe a faulty fuel injector.
I found this diagram that relates to the International 3800 chassis, which is the chassis your bus is built on. while it is not real specific, it does outline the wiring diagram. It shows the ECU/ECM b+ and ground connections.
 

Attachments

  • 99-2000 - 3800 chassis ecu power-ground wiring.pdf
    263.3 KB · Views: 22
Hey, Grimreaper86, disregard my post above (#12) and use the link instead in post #8, above.

Thanks go to Bamabus, I didn't pickup on the fact the other link is for a 3 box bus.

Here is what was shared to me, again thanks to Bamabus!

The wiring shown in the post #9 is for the three box of a 95 engine. OP has a 99. Look at the Eges 175-1 I posted previously, and see page 422 which gives the wire numbers from injectors to ecm.
 
The OS and codes should be the same between a 3box and one box. He could likely use the EGS-125 as well for fault codes.

Codes related to VPM won’t show on a 1box because there is no VPM but I believe they kept the same OS from 94-99.

If you are getting codes it is not your ECU/ECM.

Also. Start with code 124 and work your way downward. The later codes sometimes build up and come on because of earlier codes. You could clear 124 and the rest of them go away. Don’t start with the 500 and 600 level codes first. Resolve 124 then reset and see what new codes come next if any. Each time you clear a code reset stored codes and try to crank and investigate the next lowest code and follow the manual on how to resolve that code.
 
The OS and codes should be the same between a 3box and one box. He could likely use the EGS-125 as well for fault codes.

Codes related to VPM won’t show on a 1box because there is no VPM but I believe they kept the same OS from 94-99.

If you are getting codes it is not your ECU/ECM.

Also. Start with code 124 and work your way downward. The later codes sometimes build up and come on because of earlier codes. You could clear 124 and the rest of them go away. Don’t start with the 500 and 600 level codes first. Resolve 124 then reset and see what new codes come next if any. Each time you clear a code reset stored codes and try to crank and investigate the next lowest code and follow the manual on how to resolve that code.
I'll try this tomorrow. I saw a video for a different but similar bus where he described how to reset the code....I'll try that and see if that works. I think the gist is that you simply hold the diagnostic button down as you turn it on and then pump the gas like 5 times or something.
 
Yeah the location of the button is in different places on every bus but the process is the same as in the video. Count the flashes, and between codes a different light will flash letting you know the next code is coming, then write down those flashes. Until the brake light flashes 3 times then it's done with codes.

Did you find any codes?
 

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