ECM power supply lost with ignition turned on...

[Brock]

I've got the same issue with my prostar. I replaced all 4 batteries, cables, cleaned every single ground and changed the big fuses on the firewall. Did a bunch if other crap and posted on here trying to solve this issue but no luck!

Let me know if you figure this out cause I just gave up and parked the truck months ago and have been running another one. Haven't had time to play around with it.

Look up my profile and search my threads and you'll find alot of helpful ideas to check.

[Meatbag]

Well thats reassuring lol..

I'm starting to think the problem may be the ECM itself. One of the troubleshooting points on QuickServe is to make sure the ECM calibration is correct. Since I have no way of doing that...... off to the stealership she goes. I'm hoping they can just recalibrate and while they're doing that check to make sure the unit is ok.. new ones run about $2k. Fingers crossed.

[Meatbag]

(02-15-2018 )Signature620 Wrote:  I usually see 1117 caused by:

- Weak batteries as explained by ZeroNTheDark
- High resistance between batteries and the 4 pin connector @ ECM
- Drivers turning off the battery isolator as soon as they turn the engine off.

Anything that effects unswitched power to the ECM or disrupts it's powerdown cycle will give this code.

That is a good point about the weak batteries, at this point I don't remember if I load tested them or not. They are over 2 years old and the heat out here (Phoenix) is pretty tough on batteries, might as well replace them and hope for the best. After I replace them I am going to ohm test the supply harness again just to make sure. Wiring drives me insane lol...

[Chamberpains]

Somewhere along this circuit your probably gonna find a piece a wire rubbed thru, corroded, or not connected tight or your Batteries are weak and not coming up to 12v until the alternator brings the voltage up after the truck starts. Like Signature620 said : high resistance between the batteries and the 4 pin connector at the ECM.
You can easily check this circuit 2 ways. Get a multi-meter or 12v meter and unplug the 4 pin at the ECM and check the voltage reading at the 4 pin against the actual voltage back at the batteries. If it is less by any substantial amount like .2v or more you have that wire rubbed, corroded or loose. Also take your multi-meter or ohm gauge and Ohm out the ground wire using a good clean ground spot on the frame rail (the ground to the batteries is the frame rail so it gives you it's complete loop) If you get any high ohm readings then that wire is rubbed, corroded or loose. If either reading is off start the dirt fest and start tracing the wires from the 4 pin ECM connection all the way back to the Batteries or the other way around. Which ever you prefer. After you properly load test the batteries individually.

Also if you find either one of these wire with low volts or high ohms and don't feel like tracing the wire out for the break, you can just run a whole new wire from the batteries or frame. I've done this with a lot of circuit wires that I've found out of whack readings on and I didn't want to trace the connections out or it was just to minute to find where in the connection is going wrong.

**EDIT** I see the ground circuit end at Engine block ground (which does connect to the frame on most vehicles) But you'll want to ohm the ground out to this point instead. And I'm also assuming you have an ISX in your truck.

[Meatbag]

Great info, Chamber, thank you and yes its a CM871. I am watching kids for a few more hours but I'll be heading down there soon. Maybe take my 9yo and give him a lesson in headaches.

[Meatbag]

Checked every power and ground connection again, all good. Load tested all of the batteries and cleaned up the cables, good to go. Truck was still cutting out. Hardwired the battery and ground straight to the ECM, truck was still cutting out. Finally swallowed my pride and brought it to a stealership who confirmed the ECM is shot and needs to be replaced.

There goes $3k.

How is everyone else's day going lol...

[Chamberpains]

Ouch. Why are you buying the ECM through the stealership? Go find your own ECM have it programmed to your truck and shipped to you and install it yourself. Pay the dealership for diagnosis and Say Goodbye. Your truck still runs on the old ECM. So you have time to find way better prices.

[Meatbag]

Huh. Well that's a great idea, never thought of that.

(Is there a ping feature on this forum?)

@Brock, did you get all of that?