I have a 1999 Dodge Cummins 2500 4x4 5.9 It ran fine, but batt. kept draining. a friend of mine hooked up jumper cables to it, (the wrong way) then My truck wouldn't start at all. Started showing a no bus code. changed out the ecm and its still doing the same thing......I need help I just want my truck to run again like before.

 

Is the vehicle even turning over? The no bus code is a computer error indicating the bus terminal is not communicating with the dash. Tough to say what got fried, but I would recommend starting with all your fuses in both the mega fuse box and the mini fuse box.

There are a lot of potential issues. The computer could have been damaged too, but hopefully that’s not the case. I may have a spare computer you can have if that’s the case. Also recommend renaming your thread as No Bus error etc. I am new to Gen 2’s but there are a lot of good guys on the forum.

 

YES it tries to start. All lights come on but none of the gauges work. The mileage will blink then say no bus and the check engine light comes on. I've already purchased an $800 ecm plug and play. Hooked it up as directed. Does the same thing. Found 2 bad fuses, changed them out. Sad but true story. Husband messed with the fuse box after an argument. Then I had surgery the 27 th if Feb. He took my money, meds, cloths, and left me in another town from where I live. I've been on foot trying so hard to get my truck running to get my life back on track. Im 48 female needing all the advice I can get. So thank you for answering this. I'm looking for someone to try and track down the electrical. I've called the local dealerships, and the company where I got the new ecm from. I feel like I've hit a dead end. Should I change out all fuses? . Thanks again

 

There are 3 main computers that could have failed. PCM (you changed), CTM, or gauge cluster. Download the FSM (Factory Service Manual) for your year truck in the FAQ section. Wiring is in section 8W

 

That's a tough one. If somebody has messed with the truck on purpose I would start with checking that the correct size fuses are in the correct locations, both in the PDC under the hood as well as the inside fuse panel on the end of the dash. Same for the relays. That requires a bit of sleuthing as there are differences between gas and diesel and also depending on options.
Next, "no bus" is a message that relates to the CCD bus. The CCD bus is Chrysler specific though, and for OBDII compliance the PCM also implements another (somewhat) standard bus. That means that if the PCM is working, a simple OBDII reader should be able to communicate with it even if the CCD bus is non-functional. If the OBDII reader connects to the PCM the basics are working. As this is a diesel, another much less reliable way is to see if "wait to start" comes on. This light is controlled by the PCM.
There are a bunch of other modules on the CCD bus, ABS, Airbag and already mentioned timer module and the instrument panel as well as the PCM talking to all of those. Any one of these can bring the bus down at which point you'd probably need a scope to figure out what's going on.

 

If the check engine light comes on i would think it's working. Have you tried to find out what codes you are getting? Reversing polarity will fry electronics(namely the pcm) but could be more.

 

PM me a mailing address, I have the full shop manual on CD and can burn you a copy. But you will need someone who understands electrical to walk through it. Agree with everyone too, running codes can help, but ultimately it’s tracking down what was fried. There are some local pick a parts here that are pretty cheap. Next time I am at the yard I can pull something for you if track down the issue. But I will send you some photos of what Mopar was talking about for the additional computer.

You don’t need to change out the fuses, just check for blown ones, but for fun open the fuel door and remove the cap. With someone listening carefully, turn the key to accessory and see if the pump makes a mechanical sound indicating it’s getting juice. The fuel pump relay could have been damaged too in the mega fuse box.

But if it’s a computer issue, there’s probably enough of us here on the forum that have spare parts lying around and would give you one for next to nothing to help you out.