05 Mustang with a few codes

  Hello,   

I have a 2005 Mustang v6 130,000miles.  It started going into Fail safe mode randomly maybe once or twice a year after it was a few years old. I would just turn it off and back on and it would work fine.  I took it to Ford and they could never find anything except once I was on my way back to Montana in the dead of winter.  The car started going into fail safe mode conciestatly. So I dropped it off at the ford garage when i got to where i was going.   $600 later and some new sensors just to have the car do the same thing.  I picked it up and dropped it right back off twice  before I was told "the car just didn't like sub freezing temps' '.   Which irritated me but I picked it up and drove home back to Seattle and as soon as the weather warmed up a few degrees the car stopped having issues.    I can't help but wonder if this has been an issue with the car since it was new and now it's starting to all come to the surface.


So recently It started going into Fail Safe ore often, and now it always goes into fail safe mode within 100 feet of driving.    I used my code scanner and am getting 

P0102
P2160
P0480
P0481

I have replaced the MAF sensor and am still not getting any readings from it and I have also replaced the Cooling fan.   Interesting enough and yes I know this probably is not the smartest thing to do.  But after looking into the MAF wiring I saw where one of the pins looked for 12v+.  So I back probed it and shot 12v+ to the MAF and instantly the car started to run smoother. When I plugged in the scanner, I could see the MAF giving data where it wasn't before .   The car ran great for a few days before Going into fail safe mode again today.  

When I replaced the cooling fan I noticed that the wire loom going to the Plug on the Throttle body as well as the loom with a blue foil wrapped wire going down to what I am assuming is a temp sensor just below the thermostat housing was extremely brittle and crumbled as I touched it(attached image).  Not sure if things got super hot or what happened.  I was thinking about replacing the Throttle body but looking at the scope it seems to not have any dead spots and has smooth transitions when I am operating the pedal. So I'm kind of stuck. I have even started to suspect maybe it could be the ECU but I don't know for sure. 

 I have access to an old Mac Mentor as well as a Vantage Pro  but I am no autotech by any means. They were given to me by a friend who was retiring.   Any words or wisdom would be greatly appreciated.  I'm getting close to biting the bullet and running it to the Ford Garage but I have a bad feeling that they could end up changing parts until they figure it out too.  

thank you
Micahel

So after a bit more testing.

I decided to put the MAF on the scope. It was getting no reading. I then Jumped 12v+ to pin 6 on the MAF and it started reading on the scope. The car went into fail safe which is normal after running for a few seconds. I then removed power from the MAF and it stopped sending data. I reapplied 12v and it started reading again. I then left the hot wire connected and turned off the car and cleared the codes. I restarted the car with the 12v+ connected and it ran great. I ran it around and had no issues. when I parked I scanned for any codes that may even had been pending and did not get anything.

Once I removed the 12v jumper, with in a few moments the car went into fail safe mode. I pulled the codes and it pulled all the codes up as mentioned above.

Does that help anyone in helping me find my issue by chance? I traced the wire harnes the best i can with out tearing in to much but everything looks good. Except for those 2 sections of loom that crumbled

I've attached the wiring diagram for your MAF. We need to be clear on this - you're shorting B+ to the red wire, pin #6 of the MAF connector?

When you say Fail Safe, what symptoms are you talking about, specifically? Power loss, rough running, stalling? Not trying to scrutinize you, but it really does matter in this case.

If the engine never stalls or becomes a crank/no start, then I'd strongly suspect broken/corroded wire in the red wire between pin 6 at the MAF and S107. That'd explain the loss of power to the MAF while still having the engine running (since S107 is the power feed for the fuel injectors).

Hi Tyler!! First off thank you for the response! I appreciate any help I can get.

I am running a wire from the positive post on the battery and then back probing pin 6 (Violet/yellow)

When I first start the car up it runs fine for 30 seconds or so. After that it will start to run a little rough and then fail safe shows on the dash. The motor will be down on power and if givin a quick hit to the the accelerator it will miss and flutter before taking off. The car is  limiting revs. If you let off the gas and coast the car jumps and jitters a bit as it coast to a stop.

When talking about "S107". Is that a pin on the computer  or pin in fuse box or somewhere else ?

Thank you again

S107 is a splice. It's the dotted line top center of the wiring diagram with all the red wires going to it.

Is the vehicle automatic or stick shift? You mention the MAF feed being the correct color for a stick shift and those don't appear to use S107 for MAF power.

Yes, it is a stick shift

I just realised what the M/T and A/T on the schematic stood for !! That makes more sense now

Oops, I didn't ask if this was a manual or not. :blush: My mistake!

Since it's a manual, we're looking in a different area now. The yellow/violet actually comes from pin D5 of C1035B in the underhood fuse box. That pin is fed by fuse #40, which also feeds the ignition coil power on pin C5 of the same connector.

The good news is that your list of suspects is pretty short. A connection problem at C1035B, or an open in the yellow/violet wire between the fuse box and the MAF.

At this point, it's up to you to decide how deep you want to go. You can remove your jumper and follow the yellow/violet from the MAF all the way to the fuse box and test for voltage as you go. When you find solid 12V, you know you've gone past the open/high resistance. I mention C1035B because it's also possible that the pin in the fuse box itself is corroded or damaged. Keep your eyes open.

Or, you can run a new wire from fuse #40/the red wire at the ignition coil. That'll maintain the ability of the PCM Power Relay to shut off power when needed. I don't love running new wires, but some times you just need the car to work. :silly: Use grommets, tape, and conduit as needed to make sure the new wire doesn't ground out anywhere. Something like this might make the job easier:

www.littelfuse.com/products/fuse-blocks-...d-a-circuit-ato.aspx

Well,. I'm trying not to jinx this but I think it's fixed!!

I opened up to check the fuse to make sure it was good and when I pulled it there was some corrosion on on of the legs.  I cleaned it up and stuck it back in and the fuse felt a little sloppy.  So I tried to get something down in the slot to bend in a bit but that was not working so I then decided to bend the legs out a tiny bit in opposite directions and plugged it back in.  I started the car and it fired off I cleared all the codes and went for a lil bit of a drive and have not had any issues!  I'm gonna scan the codes in a day or 2 and see if anything comes up but I'm feeling good so far
Thank you guys for helping me figure this out!  I would have looked for a wire break for days in that harness with out ever finding anything

Thank you!!
Michael 

 

Following up with you, BluStang05. Still behaving as it should?

Have had no issues at all!! Sooo thankful to find this site and for the help! I bet the Ford garage would have milked me dry trying to find this issue.

NICE.

Though, honestly, I'm somewhat surprised? According to the wiring diagram, a poor connection at the fuse should have also caused a stall/no start. But hey, results are results!

That's what I was thinking as well. I figured it couldn't be something as stupid as a loose fuse. So for fun i actually pulled the fuse and started the car up and it was acting the same way it had been. As I was messing with the fuse I could get to car to die when It was running and I wiggled the fuse a bit.

And yes results are results!!