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Need advice repairing my 2005 Mustang GT

2K views 8 replies 6 participants last post by  The Handy Man 
#1 ·
Hello all I just recently bought an 05 manual Mustang GT for cheap knowing it would have some issues that I would have to fix but it seems the issues are a little too hard for me and a mechanic to figure out and was hoping some people who are smarter than me here could help me get it back up and running again. So here's what's been going on. I bought it late January and when I bought it, it would turn on and run fine (drove it 45 min home with no issues at highway speeds), then a few days later it died on me while idling at a friends house (I was idling for 20-30 minutes and had previously driven it for 10-20 minutes), I suspected something fuel related and replaced the fuel pump and checked the fp reset switch but replacing the fuel pump didn't seem to help. Checked fuses and they all looked ok.

Some info about it. Looks like it was in a light fender bender where the bumper was hit just enough to crack the areas where the bolts are holding it on under the radiator cover but it was so light that with the hood closed you can't even tell. Also (and probably important) the P.O. had cut the head lights, fog lights, and turn signal lights off and the wiring for them needs to be repaired. Im wondering if its a possible short that is causing this. I plan on finding the right gauge wire and reconnecting them. On the instrument cluster the gas gauge didn't work but I traced it back and it turned out a wire was disconnected. Reconnecting it got the gas gauge working again. PO said that he "installed" a bypass so that the car could start without the clutch being engaged (possibly because the clutch sensor is bad and he lied maybe?)

ABS light and Traction Control light are on. I pulled the DTC codes and its got a few!

B2627 U1900 C1165 P2068 P1000 P0833 P0830 P0198

Anyways, the symptoms themselves are that it started to regularly die on me. For the first start up of the day it would start right up no problem but after around 20-30 minutes of idling or driving (it would die while I'm at speeds of 20-30 mph) it would die. If I waited 15-25 minutes for it to cool down it would eventually turn back on for only 5 or so more minutes and then die again until I let it cool down. When it shut off it would crank normally but would not actually start. Crank didn't sound slowed down or anything like that.

At the time I was getting pretty busy with work so I decided to look around for reputable mechanics in town and found this guy who has been in business for 35 years and the reviews all seemed pretty good. Took it to him and after 2 months he couldn't figure it out but I suspect its because after I dropped my car off he got a huge influx of other cars to repair too which I think may have been a contributor on why he wasn't able to fix it. I told him my main suspicions were the crank shaft sensor and pcm and he supposedly only tested the crank sensor and said it was good. He also tested fuses and other things he thought could be the problem but after 2 months just couldn't even point me in the right direction.

Once I got to the shop it wouldn't even turn on. Jumping the battery didn't help either. It would just crank no start so I had to call a tow truck. Once home I noticed that there was a wire connector that was disconnected and Im not sure what it connects to. It was in between the pcm and the throttle body. Ill probably attach a picture later.

Well 2 weeks ago since my main suspicions were the pcm I sent it to get tested and today got a call that its good and that its saying 3 modules are bad (didn't say which ones but I'm fairly certain one is the abs module) and that its probably a wiring problem.

This mustang sure is proving to be a headache but Im wondering if any smart people here have seen any issues like this before. My main suspicions now are possibly that the abs module needs to be rebuilt/replaced, there is a bad diode or something burnt on the instrument cluster that is messing up the communication with the pcm, maybe a bad pcm diode, a short or multiple shorts because of the headlights and disconnected sensors, possibly replace the 2nd sending unit (but im not sure how this would cause the car to die while driving or idling) although I do have a spare sending unit too, maybe I need 2 new keys and to program them because I only got 1 key the spare key and maybe the car isn't getting a good signal from it, probably certainly replace the clutch position sensor, and getting a new engine oil temp sensor and wheel speed sensor would probably get rid of those other CEL codes.

Are my main suspects at least the majority of possible problems to you seasoned mechanics? Maybe someone has seen issues like this before? Im going to try to work on the wiring first but can anyone confirm the headlight wire gauge size? After the wiring is done going to make sure no cables or sensors are disconnected, then take a look at what's causing the abs and tc light to stay on (doesn't disappear no matter how long i press them), and go from there.
 
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#2 · (Edited)
this is way over my head, but I'd check the simple things first: fuses and relays

edit: also replace the fuel filter, if you haven't already done that (I did not carefully re-read your post, sorry if you mentioned and I missed it)
 
#4 ·
2005? You replaced the fuel pump? I would check the fuel pump driver module. I believe 2005 was when Ford went with a "returnless" fuel injection system, instead of using a mechanical fuel pressure regulator, they used a fuel pump driver module to regulate the pressure. They're around a hundred bucks.
 
#5 ·
... probably certainly replace the clutch position sensor
If all the PO did was bypass the clutch pedal position switch by shorting its terminals together so that the car thinks the clutch pedal is always at the floor - really the simplest way to solve certain interrupted-start difficulties - that shouldn't have anything to do with your car's problems.


Norm
 
#6 ·
I'm thinking that maybe he had the clutch by pass put in because he had a remote start installed for cold mornings. Remote starts can be a problem if not properly uninstalled.
The gas gauge problems along with the car dying leads me to believe you should retrace your installation steps and make sure it was done properly. Mistakes happen to the best of us.
It sounds like a fuel delivery problem.
You certainly have your hands full with this one. I'll keep digging and try to help with this puzzle.
If you can get anymore info from the previous owner it would be a big help.
 
#7 ·
I'm thinking that maybe he had the clutch by pass put in because he had a remote start installed for cold mornings.
Remote start isn't the only reason you might want to disable the CPP switch.

As set from the factory, that switch can be factory-set to open at a too-low pedal position, and they are awfully sensitive. At least on the early S197's, any adjustment you try to make to the pedal height position for the switch to open gets overridden the next time you push the clutch pedal lower than your new set point and you're back where you started.


Norm
 
#8 ·
Finally got the pcm back from being tested and got the battery fully charged so today I installed them both and decided to try to see if it would just randomly start and it didn’t. I pulled the codes again to see if they would be the same and now with a fully charged battery it has less dtc codes.

Only b2627 (fuel level sensor circuit high), u1900 (can bus communication error), and c1165 (rear wheel speed sensor).
Clutch Sensor dtc went away maybe because the battery was low at the time of the reading when I checked that day.

Tomorrow I’m going to check to make sure the wiring at the fuel pump is ok to see a fix for b2627. For u1900 I’m thinking maybe the solder welds at the instrument cluster may be cracking leading to a poor connection similar to the widespread Ford focus instrument cluster issues that would cause it to die randomly, and then I have a rear wheel speed sensor coming in the mail already. Im also wondering if the fuel pump driver module has anything to do with this as has previously been mentioned in the thread, except I would have thought the pcm would have certainly thrown a code for it.

I also have a connector in the engine bay that I’m not sure what it connects to but if I had to guess what it is I’m thinking fog lights but I’m not certain because I couldn’t find a similar connector on the other side. PO basically cut ALL the front lights off for some reason so that’s another headache to deal with haha. Need to figure out what connectors are headlights, turn signals, and fog lights... on both sides. Fml 😂

Anyways going to work on those 4 things and see how it goes. You mentioned the remote start may have been removed incorrectly. Where are some possible places they could be installed? There’s a small random box just hanging next to the fuse box that I haven’t seen in other 05-09 mustangs which makes me think it’s aftermarket.

Just want to say thanks for everyone chiming in btw!
 
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