P1234 Code Help 2007 GT500

[Boostedtres]

Okay guys and gals, before you all say "search" and "read" and this subject has been covered a million times before....I have done all that and still cannot seem to identify and solve the problem. Now with that out of the way, hopefully someone on here can help me.

I have a 2007 GT500. 17k miles, pulley, exhaust, tune. Bought from a gentleman local to me, dealer serviced, stacks of paperwork, all manuals etc etc. I use it as a DD. I am new to GT500s, but not performance cars. (Termis, Audis, Track Evo 8 etc).

Having done as much research as possible, along with always pulling and clearing the code myself, I understand the drive side fuel module offline. I am getting ZERO symptoms of an issue (no limp mode, bogging, spitting, etc) except the check engine light.

It has come on four times, and 3 of the 4 was after chirping the tires, and the 4th was a WOT highway pull. Thinking a blown or loose fuse could be the culprit, I checked all fuses and ensured there was good amp flow connectivity. All is fine. I have not touched the car in any way other than an oil change with OEM oil/filter.

I am at a complete loss, and very frustrated as this is supposed to be my comfy, reliable daily while the Evo is my PITA love/hate relationship car.

If anyone has any additional advice or guidance, please let me know. Otherwise I am going to take it to a performance shop (NoVa) or back to the dealer.

Thanks in advance.

 

[Snoopy49]

From the 2005 Mustang Service Manual.

P1234 - Fuel Pump Driver Module Disabled or Off Line
Description: The powertrain control module (PCM) monitors the fuel pump monitor 2 (FPM2) circuit from the fuel pump driver module 2 (FPDM2). With the key ON, engine OFF or key ON, engine running the FPDM2 continuously sends a duty cycle signal to the PCM through the FPM2 circuit. The test fails if the PCM stops receiving the duty cycle signal.

Possible Causes:

• 
  Inertia fuel shutoff (IFS) switch needs to be reset
• 
  Open FPDM2 ground circuit
• 
  Open circuit to FPDM2 PWR RLY
• 
  Open FPDM2 PWR circuit
• 
  Open or short FPM2 circuit (engine should start)
• 
  Damaged IFS switch
• 
  Damaged FPDM2 PWR RLY
• 
  Damaged FPDM2

Diagnostic Aids:
The PCM expects to see one of the following duty cycle signals from the FPDM2 on the FPM2 circuit: 1) 50% (500 ms on, 500 ms off), all OK. 2) 25% (250 ms on, 750 ms off), the FPDM2 did not receive a fuel pump (FP) duty cycle command from the PCM, or the duty
cycle that was received was invalid. 3) 75% (750 ms on, 250 off), the FPDM2 detected a concern in the circuits between the FPDM2 and the fuel pump.

 

[Phantomhalo]

I had the same code a while back when I was upgrading my fuel pumps. There is a fuze on the passenger side strut tower in a small rectangular box. There should be two, one for the drivers side fuel pump and the other for the inter cooler pump. I can't remember which is which so check them both. If that fuze is blown it will show as the FPDM being offline. I too checked all the other fuzes before that one and couldn't figure it out. However, fuse 66 feeds power to that small box and then splits off from there for some reason. If those are still good I would look at more of a loose connection. I was dead set on mine being a FPDM and even bought a new one but it turned out to just be that fuze. If you have any more questions feel free to ask. I know this fuel system pretty well now...lol

 

[Boostedtres]

Phantom and Snoop, thanks for the response.

I am not in front of the car at the moment, but are you talking about a third fuse box? there is the large square one on the passenger side, then a secondary rectangular one in front of it. I checked both of those, and they are not blow. I took some pics on my phone, I will try to post them. I appreciate the help and after I look tonight I may PM you if thats alright with you.

Side note, hows Ellsworth? I have a buddy coming in there from Ramstein, might be coming out to visit before I head to Okie. Oddly enough, he has a procharged 5.0 and is looking for a shelby.

Thanks again guys

 

[Phantomhalo]

If you checked the fuse and it's good then you might have a bad fuel pump. There is also a fuse labeled heated seats in the big fuse box that you may want to check also.

Ellsworth isn't too bad. There are worse places but it's definitely not Germany! Lol Windy as hell here but if he likes outdoors type of stuff it's pretty nice!

 

[Snoopy49]

 

[nxhappy]

gotta be the fuse. I doubt the pump is failing at such low mileage. Although still possible.

 

[Boostedtres]

I am going to buy new 10 and 15a fuses tomorrow and just replace them. They look visibly fine, but no need to dive into the fuel system if it (hopefully) is a cheaper easy fix. Any chance they could be bad without being burnt out visibly? I am going to head to AutoZone tomorrow after work and see if they have fuses, unless the Shelby has some spares hidden some where I do not know about.

I feel like a noob asking simple questions, but after 9 yrs in the 4g63 Evo game, this is entirely new platform. Loving reading and learning, and people here at much more helpful (less childish) than Evo people (since there cheap now).

Thanks again for all the responses. If there is anyone in the DC/MD/VA area that has input, I would appreciate that as well!

 

[Boostedtres]

Well, after a couple of frustrating days, I have new news, none of it good. hoping get some advice and maybe a little more guidance...bear with me.

i checked all the fuses as mentioned, none blown, all in the correct spot, good to go. car still drives fine, no issues driveability wise. check engine light still one, clear it, i drive normally, no problem. WOT, a little spinning of the tires, boom, P1234 comes back on.

So I go to a "well known" Muscle car shop in the NoVa area. Car has been there before, people were great to deal with, got me into to diagnose the car, and fit me in for a quick fix because as off tomorrow I am traveling to Okie for over a month. I want to have the car good to go so it can be driven while I am gone.

Diganosis: Alternator is only giving 12 volts (low from experience in cars, but not terrible). This in turn is not giving enough volts to the fuel pump at and above 5k rpms, throwing the P1234. Alternator replaced (along with new gates belt since the OEM one is too "small"). To the tune of 650 bucks. Shot to the gut, since with my now track car (Evo 8), everything is cheap and I can do it myself. Suck it up, get it fixed. No problem.

I drive 2 miles from the shop. Light comes on again as soon as I go WOT. I am told this could be an issue because it had just above a 1/4 tank of gas and with dual pumps, needs to be filled up. Questionable to me, but I am new to these motors, so I fill up, clear the code, same issue next WOT.

So now I am in the decision mode of where to look next, put a hold on the charges since the problem was not fixed, take it to a stealership, find another shop in the NoVa area etc. Frustration does not even begin describe my feels right now, esp since I will be gone until end of December.

Not trying to bash, start internet flaming, anything like that. I am just frustrated at the fact that at 17k miles, I am having a track car that is more reliable than a shelby. Should I have just bought a C63, GTR, used 996 Turbo or Viper? (I know, talking out of frustration, but you get the point).

ANY AND ALL opinions help would be greatly appreciated. And again, if anyone is in the area and meet to take a look or offer advice, happily pay in a sixer of your favorite brew. I am well connected in Imports, Evo, GTRs, M3s, but none of them cross into Muscle Car territory.

 

[Phantomhalo]

Have you checked your fuel pumps yet? I have another FPDM module sitting in my garage you can try too but I highly doubt it is that. All the crap I went through and research I did I've never read/heard of a bad one. My money is on the pump itself.

 

[Boostedtres]

No, I did not check the fuel pump itself. Its the first thing I said to them just to check the pumps (based on your advice) so I could swap that out if it was bad. But they said they were sure it was the lack of voltage from the alternator. I am seriously considering putting a hold on my CC, that pissed. Dont think I will be taking it back there if I can avoid it, from what you said, its pretty easy. Good place to get the right fuel pump at the affordable price?

So frsutrating, but ive almost burned my evo to the ground before, so not the first time. haha

 

[ShelbyGT5HUN]

Dealers sometimes are better to take the car for diagnosing, they have all the specialized testing equipment, and the techs there are used to dealing with diagnosing problems. Performance shops usually are better for straight r+r jobs, or performance parts installs. It seems like they found a bad alternator, which was verified with the voltage check, so you didn't get completely ripped off.

Perhaps you have two unrelated problems, an alternator problem, and a fuel issue. Watch out for the battery, how old is that? Five years MAX is all a battery is good for, especially these puny 550CCA ones. Twelve volts is no where near normal for a charging system! Did you throw a voltmeter back on the car to verify you are charging at more than 12V???? Parts right out the box can be bad.

I would stop running it at WOT until the problem is fixed. You could have a failing pump, a collapsed fuel sock, loose ground wire, bad battery, bad alternator, etc...

Also, anything mechanical will break, but I understand your frustration. However, the right Tech would have this figured out in an hour.

 

[Boostedtres]

ShelbyGTSHUN -- I agree with you completely. I guess I got used to and spoiled with my evo. If I couldnt figure it out myself, I have a really good friend who builds them, and will dianognose for a case of beer and not 95 bucks an hour. You have to pay to play, I get that, its just annoying.

I had like 3 hours before leaving town for holidays then Japan, so options were limited. In my limited experience, with an issue like that, I would have pulled the back seats, checked my fuel pump first. Then volts from the battery, then all connections, then the alternator etc. It seemed like none of that happened, and just went right to the alternator. Thats fine, like you said, seems like that needs to be replaced eventually anyway. so ripped off would not be what I would used to describe it, but annoyed. I have two cars, happy to leave it and have it fixed properly.

Not going WOT in a shelby defeats the purpose of having the shelby! Obviously I wont until it is fixed, but a PITA. Ive swapped multipled fuel pumped on Evos, it doesnt seem to be that much more difficult in the Shelby? DW, Walbro, OEM shelby? Pumped are cheap, getting romped by install is no good.

They one dealer ive been too is a POS with incompetent techs. Any suggestions for places to go in NoVa DC area?

An hour max. Good suggestion, I just need to find a dealer now! And then order the pumps. So much for a DD with no money going into it. Lots of driving the track car on the street. Should be interesting with the 5-0 haha. Thank you, sir,

 

[Phantomhalo]

No, I did not check the fuel pump itself. Its the first thing I said to them just to check the pumps (based on your advice) so I could swap that out if it was bad. But they said they were sure it was the lack of voltage from the alternator. I am seriously considering putting a hold on my CC, that pissed. Dont think I will be taking it back there if I can avoid it, from what you said, its pretty easy. Good place to get the right fuel pump at the affordable price?

So frsutrating, but ive almost burned my evo to the ground before, so not the first time. haha

Yeah it gets really frustrating! I hear ya on that one for sure! I have some used Fore GT Supercar pumps I can send you or you can just buy OEM ones. They are actually pretty good for OEM. I would search Amazon or Tasca for parts if you're going to buy them new. However, a lot of stealership won't install parts that weren't purchased through them.

 

[IronTerp]

They one dealer ive been too is a POS with incompetent techs. Any suggestions for places to go in NoVa DC area?

I would try Billy Wise at Bill's Auto Performance (BAP). He is a vendor on this site and his shop is right off the Beltway in Silver Spring, Md. Excellent diagnostic skills and is huge in the Cobra/GT500 scene. Goes by Wiseguy here on SVTP.