Exhaust mode malfunction - check here first

[Quick]

I wanted to post this as a bit of a PSA if you run into an exhaust mode malfunction issue. I have a 2021 Mach 1 that I purchased to use as a track car. While at the track this weekend, I ran into an issue where the car threw an error for "exhaust mode selection no available". In troubleshooting this issue, I discovered the fuse for the exhaust valves was blown. Further troubleshooting the short, I noticed that the passenger side electrical connector for the valve is relatively close to the rear body panel. Quickly pulling the connector revealed the plug apparently rubs against the body and has shorted the circuit. I'm not sure how to fix this yet and will let the dealer deal with it. However, a simple replacement of the harness won't work as it orients the connector in the same place. Bad design, Ford...

So, if you see this error, pull the passenger side plug off the valve and check for this:

 

[Thermic]

any more on this?

 

[Quick]

any more on this?

It's going into the dealer 8/25 - they are booked a ways out apparently

 

[steveespo]

These harnesses seem to be plagued with melting and pull out issues especially if the exhaust has been removed and replaced for any type of work. It is a good idea to check the routing, security, and insulation. I added additional foil tape for heat reflection on my active exhaust car. Additionally the harnesses on 2018+ cars are different than the 2015-17 GT350 cars, I am not sure if 18-21 Shelbys are the same as the GTs or not.

 

[Quick]

These harnesses seem to be plagued with melting and pull out issues especially if the exhaust has been removed and replaced for any type of work. It is a good idea to check the routing, security, and insulation. I added additional foil tape for heat reflection on my active exhaust car. Additionally the harnesses on 2018+ cars are different than the 2015-17 GT350 cars, I am not sure if 18-21 Shelbys are the same as the GTs or not.

Yeah, the problem here isn't melting, it's actually impacting the body as the exhaust expands through heat cycles. Honestly, just a very poor design by Ford. Flipping the actuator around so the plug faces 90 degrees the other direction would solve this problem entirely.

 

[wny354]

Just had the exact same issue with Mach 1 at Pittrace, blown fuse, found cut wires at passenger side exhaust valve connector. Did dealer correct problem? What is the part number of the short harness?

 

[Quick]

Just had the exact same issue with Mach 1 at Pittrace, blown fuse, found cut wires at passenger side exhaust valve connector. Did dealer correct problem? What is the part number of the short harness?

The dealer still has the car, waiting on the parts to come in. Have a mid-october date.

I don't think a new harness is going ot fix it though - heading up the exhaust is going to cause it again, I believe.

 

[Scootsmcgreggor]

if the harness is the same as normal active exhaust s550's the harness for that plug is probably 4-6" shorter than it should be, shorter than the driver's side. That plug is also part of the body harness, not on a sub-harness. So I can only imagine the fix is to get a new plug with leads and solder it in? If so maybe they can use a bit longer leads and effectively lengthen the wires to that plug 4-6".

 

[Quick]

if the harness is the same as normal active exhaust s550's the harness for that plug is probably 4-6" shorter than it should be, shorter than the driver's side. That plug is also part of the body harness, not on a sub-harness. So I can only imagine the fix is to get a new plug with leads and solder it in? If so maybe they can use a bit longer leads and effectively lengthen the wires to that plug 4-6"

No, the harness is a short connection harness that plugs into the sub-harness on the rear.

A new connector won't fix this. They have to either reorient the connector (instead of facing backwards, face one side) which would require a new muffler section with changes to how the valves are mounted, or clearance the body itself to make room for the connector.

Honestly I'd rather have a new exhaust with no valves. This is just a poor engineering design.

 

[Quick]

I got the car back. They replaced the harness and noted the clearance issue is still there. They "clearanced" the body by bending the seam back slightly, but it only added marginal amount of room.. I don't think this will resolve it, and now the back of the car is dented. Ford engineering, unfortunately.

 

[saleen367]

I had the same issue and knew the dealer would not re-engineer to eliviate the issue. They are paid to do what they do ... replace parts until the warranty expires.

@steveespo said it best... you really need to reinforce the harness where it rubs against the body surface.

I 1st pushed both sides of the exhaust forward as far as I was able to elminate interference on that passenger side. If you still have stock exhaust that might not be possible, but I had a little room working with the xpipe I had put on.
I covered the harness in a plastic wire loom that I got from Harbor Freight, then wrapped it in aluminum sheet metal tape. It won't correct the issue, but hope it will make it less frequent. I think the design was poorly engineered as you said and could have easily been avoided.

 

[k_z]

I've replaced both harnesses and re-routed (in addition to putting some more tape on the wires going to the plug) it to hopefully make it last little longer - zip tied it to some of the body parts rather than using original mounting points.

 

[wny354]

I repaired jumper harness and tried to push stock exhaust as forward as I could to gain clearance, but have no doubt wires will rub again. Terrible design from Ford, as mentioned above. My plan is simple, start car, put in track mode, and pull exhaust fuse, leaving valve open (which isn't that loud anyway)

 

[Quick]

I honestly would prefer an aftermarket option where the valves don’t exist and simply remove/relocate the stock units. Would really prefer if I could use Forscan to completely code them out.