No bus I'm stumped

[99laramie]

I got a no bus signal in my 99 Laramie, so I replaced alternator, battery, power wires and terminals, pcm, and entire wiring harness, but I'm wondering, could a bad bcm give a no bus or is it wires attached to it that could happen. It had an accident where the terminals were crossed and a couple days later nothing worked, now I have everything but the starting mechanism and electronics aren't working

 

[Daw14]

Crossing the terminals most likely fried some of the internals, that would be my guess. I’m not sure if there is a way to test it, maybe someone else can answer.

 

[Bear_Gibson]

No bus means the PCM is not communicating to the dash. If the truck won't run, then the issue can be the pcm, or the plug. I'm leaning towards the pcm. My truck would randomly shut down or not start giving a no bus on the dash. I tried replacing the plug with the bus wires on it with no luck. A referbished PCM fixed the issue 5 years ago. A no bus while still being able to drive is generally the plug on the dash not getting a good connection.

 

[macengr1]

Regarding the No Bus errors: I had the same problem with my 2012 Ram Laramie. My mechanic found the sunroof drain tube to be plugged up which ran down into the left driver's side kick panel area and caused the problem described elsewhere. In addition to the symptoms posted previously, my first clue was water dripping from the hand grab post on the driver's door. They cleaned the connections in the kick panel and covered them in dialectic grease. I was hopeful this cured the problem, which it did as far as the "no Bus" problem. However, after a large rainstorm yesterday, it appears the seal on my sunroof is in need of replacement as the water was dripping from the hand grab post again and the interior roof liner was damp. So that will be my next project. Hope this helps others to diagnose their "No Bus" problems.

 

[ThompNation]

TODAY..I took my 2012 1500 Laramie to the mechanic today for a "No Bus" issue which first happened last friday afternoon..truck starts & runs/drives, battery is 100% charged & tested good, removed the entire TIPM & cleaned/greased all connections, still getting no bus error. Also, I noticed water dripping from the driver's side a-pillar/handle and water stains in the 4 corners of my headliner last week. Over this past weekend I gutted the interior, did the "back seat folding mod" and cleared the sunroof drain hoses with air however, this youtube video does a great job showing how factory holes in the sunroof railing allows for water leakage! https://www.youtube.com/watch?app=desktop&v=0LPwgdFRMiM

its worth noting the sunroof seal does allow for leakage but the railing & drain tubes are supposed to prevent it from actually leaking into the interior.