Heavyd , truck shuts down while driving down freeway

So far i've changed all the fuses, swaped relays, put a test ecm in, replaced differential pressure sensor, coolant temp sensor, checked abs connections, replaced fuel shut off selenoid, rechecked battery conection an fuse(new conectors and batteries) aaand its still shutting off with no warning..

 

What model and year of truck? Engine?

 

09 Prostar with a cummins isx in it

 

If the engine is logging not codes then I believe it is losing the ignition signal and it simply thinks you have shut off the key. The ignition wire comes out of the firewall on the right hand side and goes along behind the wiper linkage to a connector near the wiper motor, then down to the engine. Try wiggling this harness and connector and see if the engine quits.

 

Thanks Heavyd! Last thing i did was i unplugged the ecm while engine was running to see what faults i get and guess what faults i got? Electrical fault, abs module, and coolant low. So i bypassed the whole clusterfudge and conected the ecm to the batteries directly and truck runs just fine! Good thing i didnt bring it in to a dealer i tell you that!

 

Good to hear! Electrical work still mystifies a lot of good mechanics. If the engine losses main battery supply, but still has ignition power, it will log for unswitched battery supply lost. This tells you right off the bat that the ecm power harness or main ground wiring has a problem. If it doesn't log that code, then it is losing just the ignition power which is a different wire. That is why it is good to know. Either battery supply or loss of ignition power will cause the rest of the truck to freak out in the same way. I hope you got it though! Did you put a fuse in line on the power side?

 

Yes i put a 15amp fuse on that line. The dealer mechanics most of the time are useless, they go by the book wich usually takes a lot of time and it puts a hole in your pocket. Had a friend who paid them close to 10k and it didnt even solve the problem...

 

Hey Heavy D, still trying to figure out these glitch. Heres the situation. Seemingly after windshield replacement, and when it rains, I loose my throttle, and oil gauge goes crazy, but the truck never shuts off. Had it in shop, technicians found nothing wrong. This is a 12 prostar mf13, what I check when this happens? What are the location of items? Seems to me the computer has Alzheimer's!

 

Is it possible to get code reading on my display like Sony on page 2 of this thread, if so how?

 

I think to read codes through the display a option has to be enabled. The wiring for the throttle pedal run along the dash and out the right side of the firewall and through that square connector near the wiper motor under the wiper cowl. You need a 10 mm socket to disconnect that connector, open it up and check for water or corrosion.