09 prostar with ISX randomly shutting down

[snailexpress]

(02-10-2017 )09pornstar Wrote:  So just an update...i changed that selenoid and now im on the side of I80 between Wendover and SLC.. its still doing it.. same faults on the screen low coolant, abs and electrical fault. At this point i'm at a loss for words

Find someone with Insite and check for POWER LOST WITH IGNITION ON in fault codes.
definitely power supply problem.

[Waterloo]

Sounds like a canbus/electrical issue, get to a dealer and have them put the computer on it. I bet their Diamond Logic software finds it in a few seconds. Same thing happened to me, it was a bad compass module... $19 on ebay, solved my problem.

[Rawze]

Truck would die randomly ...

Forum member 'earnies2' went to Mr. hags shop with a truck on a flat bed that was doing the same thing. He had it to several different shops, spent countless hours with several people on it, spent a lot of time and money trying to find it. He tried even resorting to using a second wiring harness, tried hard-wiring the ecm, bypassing the ignition system, etc.etc.etc. - They even replaced the ECM, some of the solenoids, and even had ground jumpers everywhere trying to see if it was a bad ground. -- nothing would fix the problem.

Sometimes it would run for a day or more and sometimes it would not make it out of a parking lot. The problem did not seem to follow vibration or rough roads, it was just annoying to the point that the truck could not be driven very far at a time.


Mr. Hag called me up when it arrived for some ideas and they both explained the whole story to me. - I told them I would stop by and help em towards fixing it since no one seemed to be able to find it so far. I told them it should not likely take more than a few minutes to find,.. and the guy laughed at me in disbelief, considering all that he has tried.


- I went there, looked over the truck a bit, then pointed out their problem. It took about 30 seconds after my arrival for me to show them that the truck died instantly whenever the top of the ECM was smacked with a hammer lightly at a certain place (top center of it where the ribbon folds over inside it).

They disagreed with me, saying it was coincidence because they had replaced the ECM before and it did not change the problem. -- I told them to buy a brand new one, put it on, and smack it on top and see if the truck still dies ...


They replaced the ECM with a new one (that didn't die when you smacked it) and they have been driving that truck ever since.

=====

That may not be what is wrong with your truck at all, but I have seen it about 10 times. Point being,... sometimes it is the simple things getting overlooked that make a problem so hard to find, and yeah.. it is not unusual to get a reman ecm and it already have this problem in it when you buy it.

[09pornstar]

Thanks aagain Rawze! I wish and hope that was the case. One problem tho.. i had a friend mail me his ecm from his prostar wich has no faults, and it was acting the same with his ecm in...

[09pornstar]

Last update guys; after i swapped the ecm, changed the coolant level&temp, differential presure, oil temp&pressure sensors, fuel cut off selenoid, inspected the ecm harness&ignition wiring, changed all fuses, i finally decided to unplug the ecm power while engine was on to see what happens and i imediately slapped my forehead..the exact same faults came on..so i bypassed all that crap and conected the ecm to the batteries and truck never shutt off since..of course i need to get a new harness or find the culprit on a warm day..i spent under 450$ so i guess im happy i didnt drop it at the dealer! With your help i eliminated probable causes one by one and its finally working so thanks a lot guys!

[Rawze]

(02-11-2017 )09pornstar Wrote:  Last update guys; after i swapped the ecm, changed the coolant level&temp, differential presure, oil temp&pressure sensors, fuel cut off selenoid, inspected the ecm harness&ignition wiring, changed all fuses, i finally decided to unplug the ecm power while engine was on to see what happens and i imediately slapped my forehead..the exact same faults came on..so i bypassed all that crap and conected the ecm to the batteries and truck never shutt off since..of course i need to get a new harness or find the culprit on a warm day..i spent under 450$ so i guess im happy i didnt drop it at the dealer! With your help i eliminated probable causes one by one and its finally working so thanks a lot guys!

check for tarnished and/or discolored fuses in the fuse panel. fuses might be good, but any discolored blades on them will cause intermittent issues.

i have had to replace almost all my fuses at least once for this by now.

[09pornstar]

(02-11-2017 )Rawze Wrote:  check for tarnished and/or discolored fuses in the fuse panel. fuses might be good, but any discolored blades on them will cause intermittent issues.

i have had to replace almost all my fuses at least once for this by now.

Daamn Rawze i did find a fuse like that when my cb was acting up and that was the culprit indeed! You know your stuff!

[Rawze]

(12-12-2019 )LRT1549 Wrote:  Here ya go Rawze.

Listen to the Lift pump go on and off.

LOLZ! Classic symptom.

{Although it is never funny to have this problem}.