Chasing random misfire - seeking Ford Performance engine harness

[mwjscn]

You used M-12508-M50, right?
I compared the picture of the part online to my harness in storage. They match up and both have the oil level connector at the very center of the 'cinnamon roll'. If so, is everything plugged in correctly?




If you're using some sort of cut-down swap harness, I'd suggest calling up their tech line. Since you have existing issues with the oil monitoring system, it makes it harder to diagnose.

 

[stevbd]

Ugh, very good catch. I ordered M-12508-M50 from PBH, as Ford Performance has discontinued this part and PBH bought up a bunch of the last remaining harnesses. This is a pic of what I ordered from PBH https://pbhperformance.com/product/gen-1-engine-harness/, which appears to be a copy of the same online pic you are looking at. But what I received does not have the oil level sensor connect at the end. I ordered the M-12508-M50 but I don't think that's what I got. Following up with PBH.

 

[mwjscn]

I ordered the M-12508-M50 but I don't think that's what I got.

One thing that may be an easy tell is if your harness has the white 'OK' inspection sticker, white and orange FoMoCo sticker, and barcode tags all right next to each other seen at the back of the harness near the firewall. Can't see if the Ford Performance has the barcode from the angle of that picture, but it does have the two stickers at a minimum. If installed, you may be able to check with an inspection mirror or a phone camera set to 'selfie' mode. I don't think PBH would replicable those if making an in-house cut-down swap harness.

Another tell would be if the box they sent you had the Ford Performance white and blue part ID sticker on it.

 

[stevbd]

What PBH told me is that when Ford Performance discontinued this harness, M-12508-M50, they were able to scoop up a last bunch of them for resale. But as you discovered what they sent me doesn't match the pic. What I received clearly isn't what's in the picture on their website. I wonder if they might have sent me an auto trans version of the harness, those are still somewhat available from vendors online last I checked.

I'm frustrated right now but really appreciate your help and everyone else's.

 

[mwjscn]

I wonder if they might have sent me an auto trans version of the harness

Check the FoMoCo sticker if it has one. The correct manual harness should have a white sticker with an orange band. It seems the color band differentiates what the harness is for ease of assembly-line identification. For instance, the automatic one below has a blue band and Gen 2 appears to use a pink band, etc.

The automatic version also has more connectors that would seem pretty obvious upon installation (like that big round one with the yellow seal in the middle), but still has the low oil level sensor connector too. Did you install the harness yourself? I think if you did, you would notice the odd connector if you received M50A. I'd bet if it isn't a genuine Ford product that it wouldn't have the correct stickers at all, either on the harness or the box it came in (and the box would say M50A on the ID sticker if that's what they sent you the auto version and it was genuine).

 

[stevbd]

I don't know exactly what I got but it's not that automatic harness. I will check when I get home. Everything on mine hooked up fine except for this missing engine oil level sensor. Yes, I installed myself and would have noticed those odd and different connections.

It looks like I'm back at square one and I think my current question is whether a 2012+ harness will work with my 2011. I have the updated 2012+ VCT solenoids. @mwjscn is that picture you posted Ford part no. DU5Z-12A581-W? It looks like what I need. Have you installed it?

For some reason, DU5Z-12A581-W shows as being available from multiple vendors but when you search for a 2012-2014 engine harness by model year they all show as discontinued? Any idea why that is?

 

[mwjscn]

For some reason, DU5Z-12A581-W shows as being available from multiple vendors but when you search for a 2012-2014 engine harness by model year they all show as discontinued? Any idea why that is?

That picture is fresh, I dug it out of my stash in order to investigate this issue with you this morning. I did a lot of research when finding the part number, but DU5Z-12A581-W is the manual transmission harness for 2012-2014 Mustangs with the updated VCT connectors, which means they will fit 2011 after the VCT solenoids have been updated. I picked it up for $144 from Tasca 2 years ago, which I thought was a much better deal than the same harness through Ford Performance for $300 or so. There are many similar cases of weird pricing models, such as a single motor mount for our 2011 GTs having a dealer MSRP of $133 each whereas M-6038-M50 gives you two motor mounts with new aluminum motor brackets and bolts for an MSRP of $165.

Looks like the M-12508-M50A is the updated Gen 2 harness, which is why it has those odd plugs on it and only fits the late-style coils which means it wouldn't even plug in on your car.

I don't know what searches you're using to verify fitment or where you're seeing discontinued stuff, but here's a screenshot right from the source - parts.ford.com


The listing for M-12508-M50 in the catalog also notes it works in 2011 cars with updated VCT solenoids, illustrating that beyond that change it works across Gen 1:

 

[stevbd]

I just ordered Part No. DU5Z-12A581-W and will do this over. Hopefully it fixes it.
Here's what you get when you try to order an engine harness by model year: https://www.tascaparts.com/v-2012-ford-mustang--gt--5-0l-v8-gas/electrical--wiring-harness
Will be removing my current harness and returning it to PBH. I don't know what it is but it's not Ford M-12508-M50, at least not as that part is pictured. I believe M-12508-M50A is the automatic transmission version.

Again, thank you very much for your help.

 

[mwjscn]

Tasca doesn't list the engine harness under their diagrams. You'll notice if you plug in the DU5Z harness into their website that it doesn't correspond to a section. In most cases it's better to use the parts.ford.com SVG diagrams instead (example of one below) since they're a lot clearer on what the actual parts are. The body harness and the front harness in your link have indeed both been discontinued.

Let us know what your results end up being.

 

[stevbd]

It appears vendors are starting to list the two part numbers interchangeably, for example this is from LMR:

https://lmr.com/item/M12508M50/frpp-coyote-engine-harness-1114-m-12508-m50?utm_source=google&utm_medium=cpc&adpos=&scid=scplp&sc_intid=&gad_source=1&gclid=EAIaIQobChMIqdvt05fciAMVIUH_AR06AQNxEAQYAiABEgL5ovD_BwE

Six weeks ago that LMR page showed just the FRPP M-12508-M50 part number and it showed as "discontinued." It was the same at most vendors and that is what eventually led me to PBH. It looks like what I tried to order and what is sitting on your floor are identical. Maybe these vendors have been reading your posts and realize they can sell the "FRPP" part under this other part number.

 

[mwjscn]

Maybe these vendors have been reading your posts and realize they can sell the "FRPP" part under this other part number.

Heh, a little potential profit to be made I suppose.

 

[stevbd]

Check the FoMoCo sticker if it has one. The correct manual harness should have a white sticker with an orange band. It seems the color band differentiates what the harness is for ease of assembly-line identification.

The harness they sent me has a FoMoCo sticker with a yellow band that says ADC on it. Dunno.

 

[stevbd]

Update, I installed the harness recommended by @mwjscn, Ford Part No. DU5Z-12A581-W, and it fits and works perfectly with a 2011 GT with the 2012+ VCT solenoids. It's also widely available for about $200. No CELs or warning lights.

A weird detail, this harness has the connector for the oil level sensor, which turned off the oil pressure dummy light on my dash but the dummy light stays off regardless of whether the harness connector is plugged in to the oil level sensor or not. So I still don't know what message or light appears on the dash if the oil level gets low but obviously I'm not going to test that.

 

[mwjscn]

DU5Z-12A581-W, and it fits and works perfectly with a 2011 GT with the 2012+ VCT solenoids.

Glad I could help! I hope that PBH was able to give you a refund on the other harness.

 

[Carls197]

Glad I could help! I hope that PBH was able to give you a refund on the other harness.

Hey I seem to be a little late and I’m new here too, I have a 2014 GT that I’m swapping a 2012 motor into (blew up the last one because of shotty dealer work) do you have a diagram of how the harness is supposed to be routed or maybe even a picture of y’all’s? Thanks!

 

[mwjscn]

Hey I seem to be a little late and I’m new here too, I have a 2014 GT that I’m swapping a 2012 motor into (blew up the last one because of shotty dealer work) do you have a diagram of how the harness is supposed to be routed or maybe even a picture of y’all’s? Thanks!

 

[Carls197]

View attachment 106104View attachment 106105

Thanks turned out I had the e pass plug wrapped around the wrong side thanks for the help

On another note along the passenger side by the condenser do you know what plug this could be?

 

[mwjscn]

On another note along the passenger side by the condenser do you know what plug this could be?

AC Clutch connector C100?

 

[Carls197]

AC Clutch connector C100?

View attachment 106107

Thanks got it figured out waiting for my boss tune and I’ll fire her up thank you again

 

[BackInBlack]

@stevebd, did the new harness/solenoids fix your misfire issue?