Anyone fimilar with 9400i 870cm

[608trucker]

So I have a few concerns I dont know if I'm just looking in the wrong areas or what kinda new to the page. But I'm having a code thrown for sid-251 fmi 2 so its saying there is a power loss to ecm if I'm understanding correctly. Also my voltage gauge stock gauge an aftermarket only read 13.2 to 13.5 an stealership says that's normal but I'm not use to that at all. My other trucks with same motor all read higher then 14. But anyways does anyone know what pin or wires on plug I should look at for this code being thrown I've heard of people running a jump wire but no diagram or pin count if anyone could share some light on this I would be extremely grateful also looking into the future for some off road applications thank you for your time.

[DDlighttruck]

If you register that motor on Quickserve you can look up all the CELs, and look up the troubleshooting tree to follow.

It’s free

[Waterloo]

Here are all of the circuit schematics from Navistar, I did not see your truck, but that does not mean it is not there...

Link one, to schematics http://bodybuilder.navistar.com/General/BBcircuitIX.htm

Link two, this is the main site for Navistar Body Builder where you will find even more information... http://bodybuilder.navistar.com/General/Home.Htm

This should get you pointed in the right direction.

For Cummins, https://quickserve.cummins.com/info/index.html

Engine serial number and register it.

[DDlighttruck]

Oh and grab a multimeter, with it idling see if the volts output matches the gauge in the dash

[Waterloo]

In the cold weather, my voltage drops, I would say you are of ok voltage wise. How old are the batteries?

[608trucker]

Thank you all I've test all the batteries an the come back testing fine. I'll have to recheck an see how many wires are coming off the alternator when I get back to the truck. It throws a constant warn engine light an that's the only code that pops up as soon as I have some one clear it comes right back on and the stealerships play guessing games while scratching their heads at 1k a pop it seems like an I'm really. Not trying to play that game. I wont be back to the truck for a few weeks I ended up parking it an jumping in another one of my trucks for time being. Wasnt trying to go down on the road cause we all know how expensive that is

[Chamberpains]

Waterloo, bodybuilder doesn't get in to pre Prostar year models. The 9000 model trucks schematics are are bit hard to find. But they are out there.

I didn't read much of the other guys responses but your alternator voltage is fine.

You more than likely have a wire broken or starting to corrode going to the ecm. More than likely from the battery box and around it. Check the fuses and wires in the battery box. Also check around the ECM harness's especially the 4 wire plug and wires going in to the ECM. That is the main power/ground plug.

Quickserve will have detailed pinout diagrams for you engine and ECM. You can always skip the dirty work of pulling all the wiring out of the frame rail by just running all new properly protected wires up to the ECM. just leave the old crap in place.

[DVT873]

(12-13-2019 )608trucker Wrote:  Thank you all I've test all the batteries an the come back testing fine. I'll have to recheck an see how many wires are coming off the alternator when I get back to the truck. It throws a constant warn engine light an that's the only code that pops up as soon as I have some one clear it comes right back on and the stealerships play guessing games while scratching their heads at 1k a pop it seems like an I'm really. Not trying to play that game. I wont be back to the truck for a few weeks I ended up parking it an jumping in another one of my trucks for time being. Wasnt trying to go down on the road cause we all know how expensive that is

608, post a VIN and PM me an email address. I have A pretty complete library of circuit diagrams for cornbinders. For now check all the wiring down at the starter. That is often used as a junction point there will probably be several smaller wires coming off the stud that the cable for the battery attaches to. They often get loose or have corrosion or the terminal Crimps on.

[Mr Hagg]

Ok so depending on the alternator you have will depend on what the out put is. What I would do it at the alternator it self see what the voltage is coming out. Then check it in the cab. You will see a drop of like .2 or so thats ok.
The fault code you posted quick serve says its a clock battery.

SPN FMI Lamp Color Description
251 2 Maintenance Real Time Clock - Data Erratic, Intermittent, or Incorrect
Effect
None on performance. Data in the ECM will not have accurate time and date information.
Component Location
The real-time clock battery is secured to the engine harness near the ECM. Refer to Section E for a detailed component location view.

Under ordinary operating conditions, the real-time clock in the ECM is powered by the vehicle's batteries. If battery power to the ECM is lost, then the real-time clock will be powered by a battery in the engine harness (if equipped).

Ive ever saw what its speaking of but there is a jumper from the 4 pin connector to ecm, If you look upper left of ecm you will see the square 4 pin plug. follow wires back to battery source. About a few inches you should see a break out in it with 2 wires plug going back into ecm harness that will go to pins 35 and 47 on the engine harness side. Check volvage there.I have found in the past that where the wires split off will have a bad connection and drop voltage....