03 GT Engine Control Electrical Issue
05-12-2011, 03:08 PM
#1
Thread Starter
Join Date: Jul 2010
Location: MD
Posts: 4
03 GT Engine Control Electrical Issue
Hey guys, I'm new to the forums! I can usually find out my Mustang issues by searching, but I believe I have an electrical problem here that seems pretty rare.
Backstory: About a month and a half ago I washed my engine (followed some very strict guidelines, such as washing it COLD, covering CAI, battery and alt, etc etc) but thought the coils would be okay. I ended up losing a coil, but no big deal, I have a couple extras. At this time I blew a fuse for F2.8 (Engine Controls under dash) twice; once the day of (I believe) and again a few days later. Naturally, I got all the codes for O2 sensors and whatever else that fuse controls (I don't know the length of it all). Fuse was fine after that.
Since then I developed a hesitate/jump/buck of some sort when I go over any kind of bumps in the road, whether it's bumpy pavement, a change in pavement, imperfect cement laying, or sometimes even as much as a dog turd in the road (not literally). Sometimes it's a pretty light tug and other times it can be pretty violent and it scares the crap out of me. Over the course of time, this has gotten worse to the point where the Theft light has come on and blinked as well as speedo and tach have went to zero momentarily and then shot back up to where they were. The speedo/tach issue has happened three times and all three times it was accompanied by the Theft light. The Theft light HAS come on without the speedo/tach issues though maybe seven times total. This has NEVER happened before I washed the engine (may not be the cause, but could have sped the process up of a wire going bad). While this has happened, the car has NOT turned off or had any kind of trouble starting, even when the Theft light came on, which leaves me to believe it's not a PATS issue, even though it's blinking the 1:6 code (some sort of communication issue, I don't have the info in front of me atm).
Well a few days ago, I blew the F2.8 fuse again and while I had the CEL on, I did NOT experience the hesitation/jumps/jerks over bumps. I don't know how long the light was on (actually noticed it on after it had jerked) but I really don't think I felt the hesitation, which is why I think the two issues are related. I obviously don't want to drive the car around without that fuse too long. However, now whenever I replace the fuse, it blows at key-on.
No CEL besides when the fuse blows, which is why I believe it to be an electrical issue or some sort. I figured out a few days ago that the cluster has a self-diagnostics thing that can store it's own, seperate codes (or something like that). Since I had a Theft light blinking and speedo/tach issues, I checked into it and I have three codes stored there which came up as dtc5284, dtcd147, and dtcd262 (this is exactly how the dash showed them). From what I understand, the 5284 is a common code and isn't anything to worry about if I don't have other sensors going off, according to PaladinMicro (http://www.paladinmicro.com/pmicro.php click on "Repair and Maintenance" and then "Instrument Cluster Diag"). I haven't found too much on these D related codes besides here: http://www.fordforums.com/f166/dtc-codes-81076/ but it doesn't go into fixing them or why they appear.
The closet I've come to figuring this out would be a TSB someone posted for me on another board (http://www.bullittarchive.com/7020.htm). It's the very first one on the page. Also, from what I understand, the codes on that particular TSB (U1147 and U1262) are equivalent to the two I'm seeing on my dash self check (D147 and D262). My BEST GUESS at this point is that something relating to fuse 2.8 (Fuse #8 in the interior panel) is chaffing/rubbing/shorting out on something relating to the VREF/DPFE, although I am not familiar with what either of these are (or if they're the same thing). I've checked for this particular issue (I don't have a bullitt, but I do have a Steeda) and this particular issue is not the case.
Sorry for the life story, I just want to make sure I am as clear as possible so I can get the correct help. I also posted about this on Stangnet when I figured out about the issue, but at the time I thought it was some sort of misfire since the fuse was okay and I had a past issue with the coilpack when this started, so I thought I'd try somewhere fresh to me. I'd appreciate any and all help that can get me pointed in the correct way! If I'm unclear about something, let me know and I'll try to explain in better detail!
Also, one last note. I was under the car last night and all the O2's look fine except for one that looks like it has a bit of oil/black crud on it. I unplugged it (left it in pipe, unplugged the harness) and still blew the fuse at key-on. I assume the other three, which look better, are fine.
Backstory: About a month and a half ago I washed my engine (followed some very strict guidelines, such as washing it COLD, covering CAI, battery and alt, etc etc) but thought the coils would be okay. I ended up losing a coil, but no big deal, I have a couple extras. At this time I blew a fuse for F2.8 (Engine Controls under dash) twice; once the day of (I believe) and again a few days later. Naturally, I got all the codes for O2 sensors and whatever else that fuse controls (I don't know the length of it all). Fuse was fine after that.
Since then I developed a hesitate/jump/buck of some sort when I go over any kind of bumps in the road, whether it's bumpy pavement, a change in pavement, imperfect cement laying, or sometimes even as much as a dog turd in the road (not literally). Sometimes it's a pretty light tug and other times it can be pretty violent and it scares the crap out of me. Over the course of time, this has gotten worse to the point where the Theft light has come on and blinked as well as speedo and tach have went to zero momentarily and then shot back up to where they were. The speedo/tach issue has happened three times and all three times it was accompanied by the Theft light. The Theft light HAS come on without the speedo/tach issues though maybe seven times total. This has NEVER happened before I washed the engine (may not be the cause, but could have sped the process up of a wire going bad). While this has happened, the car has NOT turned off or had any kind of trouble starting, even when the Theft light came on, which leaves me to believe it's not a PATS issue, even though it's blinking the 1:6 code (some sort of communication issue, I don't have the info in front of me atm).
Well a few days ago, I blew the F2.8 fuse again and while I had the CEL on, I did NOT experience the hesitation/jumps/jerks over bumps. I don't know how long the light was on (actually noticed it on after it had jerked) but I really don't think I felt the hesitation, which is why I think the two issues are related. I obviously don't want to drive the car around without that fuse too long. However, now whenever I replace the fuse, it blows at key-on.
No CEL besides when the fuse blows, which is why I believe it to be an electrical issue or some sort. I figured out a few days ago that the cluster has a self-diagnostics thing that can store it's own, seperate codes (or something like that). Since I had a Theft light blinking and speedo/tach issues, I checked into it and I have three codes stored there which came up as dtc5284, dtcd147, and dtcd262 (this is exactly how the dash showed them). From what I understand, the 5284 is a common code and isn't anything to worry about if I don't have other sensors going off, according to PaladinMicro (http://www.paladinmicro.com/pmicro.php click on "Repair and Maintenance" and then "Instrument Cluster Diag"). I haven't found too much on these D related codes besides here: http://www.fordforums.com/f166/dtc-codes-81076/ but it doesn't go into fixing them or why they appear.
The closet I've come to figuring this out would be a TSB someone posted for me on another board (http://www.bullittarchive.com/7020.htm). It's the very first one on the page. Also, from what I understand, the codes on that particular TSB (U1147 and U1262) are equivalent to the two I'm seeing on my dash self check (D147 and D262). My BEST GUESS at this point is that something relating to fuse 2.8 (Fuse #8 in the interior panel) is chaffing/rubbing/shorting out on something relating to the VREF/DPFE, although I am not familiar with what either of these are (or if they're the same thing). I've checked for this particular issue (I don't have a bullitt, but I do have a Steeda) and this particular issue is not the case.
Sorry for the life story, I just want to make sure I am as clear as possible so I can get the correct help. I also posted about this on Stangnet when I figured out about the issue, but at the time I thought it was some sort of misfire since the fuse was okay and I had a past issue with the coilpack when this started, so I thought I'd try somewhere fresh to me. I'd appreciate any and all help that can get me pointed in the correct way! If I'm unclear about something, let me know and I'll try to explain in better detail!
Also, one last note. I was under the car last night and all the O2's look fine except for one that looks like it has a bit of oil/black crud on it. I unplugged it (left it in pipe, unplugged the harness) and still blew the fuse at key-on. I assume the other three, which look better, are fine.
05-12-2011, 08:45 PM
#2
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
D147 and D262 are both related to invalid or missing SCP (Serial Communication Protocol) data, this is Ford's nomenclature for the J1850 OBD2 data bus, which is used by the PCM, instrument cluster, and ABS communications.
I highlighted ABS above because it's the only of these components that lives under the hood--if water got into that connector it could affect the SCP bus signals.
I highlighted ABS above because it's the only of these components that lives under the hood--if water got into that connector it could affect the SCP bus signals.
05-12-2011, 09:03 PM
#4
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
And,
F2.8 supplies power to all four O2 sensor heaters, and also the the EGR vacuum regulator solenoid, and the EVAP purge valve and canister vent.
The EGR regulator is on a bracket to the rear of the driver's side of the upper plenum, the EVAP stuff is in the rear of the passenger side fender.
F2.8 supplies power to all four O2 sensor heaters, and also the the EGR vacuum regulator solenoid, and the EVAP purge valve and canister vent.
The EGR regulator is on a bracket to the rear of the driver's side of the upper plenum, the EVAP stuff is in the rear of the passenger side fender.
05-13-2011, 09:58 AM
#5
Thread Starter
Join Date: Jul 2010
Location: MD
Posts: 4
Hey Cliffy, thanks for the replies! I had that same wiring diagram you posted, as well as another one that I printed which showed the other connections running from Fuse 2.8. I double checked a lot of wiring in the engine compartment yesterday and I actually found a loom behind the DPFE bracket that was burnt through. It was facing down and was burning/rubbing on some sort of pipe that was covered with the worse kind of crap that was really just falling apart. I ended up having to cut some of the loom off to expose the wiring so I could fix them. I ended up repairing a good 4 or 5 wires with exposed copper. I rerouted the loom (after properly repairing it, of course) so it wouldn't rub against this pipe anymore (still have no idea what it is.. AC/heat related I would have to guess). Nothing four thick, yellow zip ties couldn't handle. I heard yellow zip ties add 5hp per anyways 
.
Regardless, issue solved! Good luck to everyone not having this happen to them, it was kind of a pita to troubleshoot, thought seemed so simple once I found it
.Regardless, issue solved! Good luck to everyone not having this happen to them, it was kind of a pita to troubleshoot, thought seemed so simple once I found it
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