E C M 3126 b cat

[Randall Gibbons]

wiring diagram i think i have a ground wire broke on 3126 b cat  1998 beaver patriot

[Joel Ashley]

Randall, are you saying you need the wiring diagram?  The closest available in the club’s Coach Assist section is for a ‘96 and ‘02-03 Patriots.  But even so, and even if your specific engine is shown, diagrams typically show how things are connected but not where to actually locate wires and connections. 

It’s likely someone here can advise you, but they’ll need a little more information, such as what symptoms are indicating a broken ground, why you mentioned the ECM, and any other detail that will help them point you in the right direction.  🙂

Joel

[Dave Atherton]

Randall, not knowing in-depth of what is going on with the ECM on your 3126 B engine but I
can direct you to your problem. Let’s start at what is call J-1 Data port that is located closest
to front of motorhome, we use this port for data cable and key switch power on/off that connects
Into J-1 on ECM. Looking at rectangular connector that plugs into the ECM ( look very close at
the lower left corner on connector wire harness ) the wire we are looking for is a Red wire that
is the 12 volt the connects to ECM is pin 70, this wire powers your ECM that is a on/off off your key
Switch. In most all cases you lost power going to Pin 70 that again is a 12 volt wire that has to
be hot to power up ECM. Engine will turn over but will not start. If you cannot get any power going
to pin 70 with key on  than you need to go and check power source going to the key switch.
If fuse panel location front compartment driver side, there is a 12 volt solenoid on bottom little
off set from center fuse panel. First check for power at solenoid with key on/off. If you have power
with key on than on right side of panel about 5 /6 down from top you will see ECM power.  ( yes you
Will need power going to ECM and may need to jumper wire from 12 solenoid on bottom to make
system work. Dave Atherton Retired Cat Mechanic

[Mike Shumack]

You can get wiring diagrams here https://www.thetruckersreport.com/truckingindustryforum/forums/heavy-duty-diesel-truck-mechanics-forum.409/ You have to register/sign-in to the forum to access the info.
Under the CAT link, they are listed by engine serial number (such as "KCB" for the C13 ACERT, C7S, etc.)

[Randall Gibbons]

thank, i will try that.   motor started ran about 2 minutes and die out, now it wont start at all. A mechanic came put it on his computer program


 

[Randall Gibbons]

Sorry new at this !     1998 beaver patriot 37' 3126b cat it ran for about 2 min  die out wont start now.  i found that rectangular plug has hot spot in two of the pins that plug in E C M  they got very hot looks like.  I dont know why

[Steve Huber Co-Admin]

Randall,
See if you can ID the pin#s. Also do you see any evidence that the ECM receptacle also got hot? If so it would indicate a problem in the ECM. More likely is that the plug that got hot has a quasi short between the 2 pins causing the over-heating. Look for a trace between them and/or measure the resistance between them with an ohm meter, but be sure you have the other end of the cable unplugged if it is the one that runs to the diagnostic plug. Otherwise it will be difficult to ensure the wires are open on the other end unless you know the pin#s and the sensors they attach to. You can then disconnect them at the sensors.
Steve

[Randall Gibbons]

Thanks ill try that