ECM Bad???

It doesn't sound like a bad ECM but a bad harness. Some of these harnesses have multiple points for fuses for the ECM to connect to the battery and they have problems with corrosion and broken wires, etc.

My FL used to spit out low ecm voltage codes all the time when it got cold, that was then the connections contracted and loosened up within the splices. I could not figure out what the problem was until I read on some school bus site what was going on and once I got the harness off, cleaned and re-splice the connections the right way, it went away.

Here is a link that will explain it to you, I would download it and print the pages you need to find the connections.

http://www.dmbruss.com/images/Schematics/DDEC/46_Flash_Code_46_Battery_Voltage_Low.pdf

 

Thanks for this info. I could of used this chart a while back & saved me a lot of time, money & aggravation.

 

16 Coolant level sensor circuit
46 Sensor supply voltage low and or ECM battery back up voltage low
43 Coolant level low
44 Coolant, oil, air temp high
61 Injector response time long
77 Fuel temp above/below range
41 Too many missed SRS

Yellow are stored codes, no way to know when without DDDL. Red are active codes.

How did you measure voltage? Just unplugging it at probing it will not tell you much. It needs a load on it. The best way is to back prob it with it hooked up and powered. A bad/corroded wire/connection may show battery voltage unloaded, but has a big voltage drop when you power it up. Also check the grounds by going from the ground to the battery positive.

If your only active code is 16, then you have a coolant level sensor or wiring issue in that circuit. That should not keep it from starting though, if coolant protection is set for shutdown, it should start and run for 30 seconds. I'd fix that issue first and any other active faults.

 

46 is batt ecm shot out. 44 = overheated sometime in lifetime.61=injector responce timeing 2 long, did they enter new # on injector into ecm. 41=CKP sensor bad 77 misc.falt I not sure on this one. pitt. burg power can replace batt. in ecm if u send it to them 724 360 5092 call them they can do batt.

 

Don't condemn the ECM batt, it is an inactive fault. All those inactive faults could be from low voltage at some point, but you wont know when unless you get it hooked up to DDDL. I'd only worry about your active fault 16 right now. 90% of the time, a new plug on the harness end fixes that. The 2nd most common is the sensor itself failed, but that's actually pretty rare. The coolant level sensors do gum up giving a false reading often, but code 16 is high voltage, typically an open in one of the wires. I wire to the sensor is ground and the other goes to the ECM. Give each wire a good hard tug, they usually break internally right at the plug. If you pull a wire apart, it needs a new plug end.

 

If you replaced the camshaft did you tighten the camshaft bolt to spec? You might want to inspect that as well.