4.0 to 3.7 V6 swap

[Juice]

If you get no power to the WH-GN, the starter relay will never energize.
The Yellow wire is the ground circuit for the starter relay, this is what the pcm should grounds to crank it over.
So, no power to the the WH-GN is the issue, and, since it is coming from the SJB with the power fault DTC, this is why its not cranking over.
Now, what the heck is "micro start"? I have an idea of what it is, but not sure.

1 With the starter relay removed, I would use a DVOM to see if there is any voltage on the green/white. You know you don't have 12V, so is it very low volts or zero volts at pin 86 of the relay?
2 To check if the PCM is grounding the starter relay, connect one lead of the DVOM to battery + and the other to the yellow wire. DVOM should read batter voltage while the key is in crank position at pin 85 of the relay.

 

[TARA-fied1]

If you get no power to the WH-GN, the starter relay will never energize.
The Yellow wire is the ground circuit for the starter relay, this is what the pcm should grounds to crank it over.
So, no power to the the WH-GN is the issue, and, since it is coming from the SJB with the power fault DTC, this is why its not cranking over.
Now, what the heck is "micro start"? I have an idea of what it is, but not sure.

1 With the starter relay removed, I would use a DVOM to see if there is any voltage on the green/white. You know you don't have 12V, so is it very low volts or zero volts at pin 86 of the relay?
2 To check if the PCM is grounding the starter relay, connect one lead of the DVOM to battery + and the other to the yellow wire. DVOM should read batter voltage while the key is in crank position at pin 85 of the relay.

YES, what is "micro start"!!! I was wondering that too! I have a Fluke Multimeter/DVOM.
I thought the yellow wire was supposed to have 12v? (which it doesn't). I was using my test light to check key start position stuff since I am doing this alone. I'll recruit some help. Thanks for sticking with me.

 

[TARA-fied1]

 

[TARA-fied1]

after I made the video I decided to pull the SJB and clean it as best I could. I pulled every fuse and tested them before putting them back. I don't think there was enough corrosion to be the problem with no crank but might have caused the DTC. I used alcohol, plastic bristle brush and Q-tips. I'll let dry tonight and put back in tomorrow. Not optimistic it will have made any change though.

 

[TARA-fied1]

after googling SJB's I found a web page on how to repair a SJB so I took mine apart to clean it even better.
https://www.ifixit.com/Guide/How+to...3+2014+Ford+Mustang+Smart+Junction+Box/124407

 

[Juice]

Thats a bit more corrosion than I like to see.
My guess that "micro start" maybe the feature where you only have to tap start, and the pcm keeps the starter turning till the engine starts.

 

[TARA-fied1]

Thats a bit more corrosion than I like to see.
My guess that "micro start" maybe the feature where you only have to tap start, and the pcm keeps the starter turning till the engine starts.

Well I think I got all the corrosion from the SJB. I’ll need to clean the connectors before reinstalling.
The theory on the micro start makes sense.


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[TARA-fied1]

update, the SJB cleaning didn't fix the problem but I am glad I did it. So I tried to jump the starter at the BEC through the relay connection. I made a jumper wire and connected #30 to #87 and nothing happened. This suggested to me that there was a disconnect somewhere in the harness. There is a connector in the engine harness that comes off the C1381E harness.

I unplugged it to do some checking with the Fluke and noticed it was soaked in antifreeze. I suspect when I pulled the engine and the coolant pissed out all over when tilting the engine, it poured onto this connector. I didn't pay attention to this when plugging it in during reassembly. However, I sprayed some electrical cleaner in the two connections and used my air compressor to dry it really well. When I plugged it back together the car fired right up!!! This was very frustrating but I am glad I went through the process. I have learned a lot and I appreciate everyone's comments and help.
Now I need to modify the tail lights and button up a few other things and I can take it for a test drive! More to come...

 

[Juice]

That's great! Its alive !!

 

[Dino Dino Bambino]

That's the sweet sound of victory.

 

[JimC]

That's great! I know that you were frustrated and ready to give it up, sometimes it's a simple thing that you just have to work through to find.

 

[TARA-fied1]

That's great! I know that you were frustrated and ready to give it up, sometimes it's a simple thing that you just have to work through to find.

Yeah, I was ready to light it on fire!


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[GlassTop09]

Yeah, I was ready to light it on fire!


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Good deal! Glad you finally traced it out & found the disconnect.

Now since you've noted 1st hand how little it takes to disturb\interrupt a low voltage electrical connection, I would highly suggest that you get some dielectric grease & a small brush & start using it on every electrical connection....including fuses & relays.....you pull out\take apart after cleaning\repairing\replacig it before you reconnect it..........using this grease will go a LONG way to stop\prevent what you've just experienced from happening in future.......

Just a suggestion...............

 

[TARA-fied1]

Good deal! Glad you finally traced it out & found the disconnect.

Now since you've noted 1st hand how little it takes to disturb\interrupt a low voltage electrical connection, I would highly suggest that you get some dielectric grease & a small brush & start using it on every electrical connection....including fuses & relays.....you pull out\take apart after cleaning\repairing\replacig it before you reconnect it..........using this grease will go a LONG way to stop\prevent what you've just experienced from happening in future.......

Just a suggestion...............

this is a great suggestion! thanks again for your help.

 

[TARA-fied1]

sitting on the ground and ready to drive. I need to modify tail lights to be street legal but I can run around the neighborhood anyway! My son's T-Bird is in my way at the moment. Swapping the trans in it.

 

[JimC]

From that picture I think that you will need to modify the hood, or get something aftermarket. As was discussed earlier, the 3.7 sits higher and it sure looks in that picture like the intake is higher than the strut towers.

 

[mattjames]

From that picture I think that you will need to modify the hood, or get something aftermarket. As was discussed earlier, the 3.7 sits higher and it sure looks in that picture like the intake is higher than the strut towers.

The hood curves up, I think if my Coyote with a Boss 302 Intake manifold fits under my stock 07 hood, he should be fine.

 

[JimC]

The 3.7 is a taller engine than the coyote, that is where the issue may come in with the switch to putting it in the 2007 car. The 5.0, even with the Boss intake, doesn't sit as high as the 3.7

 

[Juice]

Do the 11&up cars get a different hood if equiped with a 6 or an 8?
No.
My bet is the hood will close no problem.

 

[TARA-fied1]

I actually don't have a stock hood. I put a cowl hood on years ago. The debate will have to continue!
This pic is from before I took it apart for the swap but I guess it should clear. It might go on tonight if I can get help putting back on.