04.5 ECM Wiring Harness Question

[weazel]

I’m back to working on my CR engine to 2nd gen truck conversion. I have run into a couple of connectors in the ECM wiring harness that I can’t figure out where one of them goes.
This harness came from an 04.5 manual truck, was just the cab when I pulled the harnesses.
In this photo it shows two connectors. The black square shaped one plugs into the positive side battery cable, but the wire I’m curious about is the one with the ring terminal on it. Most of the trucks around me now are later models with 6.7s, and later model 5.9s with the newer fuse boxes.
Can anyone give me an idea of what this wire connects to? It’s about a 12-14 gauge size wire, black with red (maybe orange?) stripe.

 

[kleann]

Looks like the ground that bolts behind the driver's side battery tray onto the fender support.

 

[weazel]

Ok thanks for the info! That helps me out a lot!

 

[pushlar84]

That is correct

 

[weazel]

Ok have another question, I’m attempting to figure out what harness and where it goes for these two connectors, any ideas?

 

[kleann]

It probably goes back into the transmission harness. Does the other end connect into the smaller plug on the ECM?

 

[weazel]

From what I can tell, these two go into loom and go into the cab

 

[QMFB]

Ok have another question, I’m attempting to figure out what harness and where it goes for these two connectors, any ideas?

Looks like the secondary diagnostic ports that are found in the engine harness just below the intake plenum in the 3rd gems.

 

[weazel]

Looks like the secondary diagnostic ports that are found in the engine harness just below the intake plenum in the 3rd gems.

Hmm, I wonder if I’m missing something? I am unable to communicate with the ecm right now.
I’m able to crank the engine with the key now, but the lift pump does not turn on.

 

[weazel]

The blue connector has a wire that goes to the fuel pump relay. So I’m not sure if I’m still missing another harness, or if I can leave it open like it is

 

[BigPapa]

Can we get a little more “head on” pic of the connectors? And the wires going into it?

 

[weazel]

Here’s what I could get

 

[BigPapa]

Excellent. I’ll see what I can find on them tomorrow.

 

[weazel]

Excellent. I’ll see what I can find on them tomorrow.

Thank you!

 

[BigPapa]

Nothing to do with the engine.

 

[weazel]

That answer a lot of my questions, thank you for sharing that info!
I’m guessing I have a bricked ecm since I am unable to communicate with it through the obd port.
Also another weird thing this setup does is when I connect the battery, the key is “off” the dash cluster will turn on. Will say “no bus”. I turn key to “on”, will show mileage. But that’s about all it does lol. Won’t ever turn off. Could this be related to the FCM? Along with an ecm issue?

 

[BigPapa]

Upon further inspection, there are circuits for the Fuel Pump, Speed Sensors, and Sensor Grounds in these connectors.

 

[weazel]

Ok, thank you for looking into that further! I’ll see if my friend still has that cab I robbed this harness from and see if that side of the harness is still there.

Seeing that there’s a couple of ground connections in those plugs, would that have anything to do with the ecm not wanting to communicate? I guess I’m thinking out loud here lol.
I attempted to hook up an early 04 ecm to these harnesses, but it doesn’t communicate either

 

[BigPapa]

I don't know about the ground and ECM. I'm just IDing connectors for you....:lolly:

 

[weazel]

I don't know about the ground and ECM. I'm just IDing connectors for you....:lolly:

LOL thank you very much for the info you provided!