Hi ,new on here so be gentle ! I have a 2014 GT 5.0 my fuel gauge is reading 1/2 full but it should read full ,I stupidly let an auto electrician loose on my car , he tapped into one of the positive supply wires that connect to FPCM he wanted to steel a bit of +power to add to my brake lights via a relay as the brake lights didn’t have quite enough to power them correctly.although my break lights now work fine my fuel gauge started going crazy and is not reading the correct levels . The guy in question now says he thinks he has mucked up the FPCM and it should be changed ! Does anyone agree with that analysis as I thought the FPCM only regulates the fuel supply and the car is running fine So this doesn’t make sense to me .

any help would be very appreciated

 

Welcome to the forums!

First... I'm not happy with your guy. What the entire heck. That's just... I don't know. Why. There's better places to get power. Lazy, wrong, just... don't call him an electrician.

Second:


You *fix the problem directly* on that. I just... I don't EVEN know what the guy was thinking... So yeah. You're probably getting a FPCM, but first and foremost, you're ripping out (correctly, mind) that goofy wiring job entirely, put the brake lights back to stock, and get it fixed right at the dealership or *reputable* shop. But I wouldn't be surprised removing the botch wiring job doesn't fix the gauge, and then you can fix the dim brake lights another way. Whatever you do, dump this guy promptly, don't let him touch your car to fix this, just remove him from your contacts regarding such things. Find someone else to do the work to reverse the mistake, and yes, you will pay them to do so. Sorry.



I'm just irrationally angry at this situation for you, and I apologize for that. Truly. But I have no idea why he's doing this in the first place, much less obviously why he did it the way he did. So could you maybe enlighten us as to why the brake lights seem to be not bright enough? Did you swap out tail lamps or bulbs or something? Did you smoke/tint them and it's now a concern they're not bright enough? That story would help greatly in understanding why this even took place at all and maybe provide a proper solution path.

Hope we can help, and thanks in advance!

 

Hi, thanks for your comments and yes frustrated doesn’t go far enough ! Explanation of how it got to this stage , I bought the car new and had it shipped to the UK the lights had to be converted for UK roads so the original set up had to be changed ,I used a company that was highly recommended for this type of conversion ,however there was a glitch with the now new brake lights ,there was insufficient power to turn on both lights and the trunk light together as the circuit now used for the brake lights may have only powered say the reversing lights before ! So more power was needed to increase the extra drain . I totally agree with you a separate fused supply should have been run to achieve this . But I think you are also correct in saying he took the lazy way out and decided to steal it from the FPCM as it was the closest. He has now changed this and taken it from the permanent power supply from the base/subwoofer which is less important but still not ideal ( still the lazy way out ) but brings it back to why my fuel gauge is playing up as I didn’t think the FPCM controlled the fuel gauge ! I can’t tell you how pissed I am as my car is my pride and joy ! it has had every Ford racing extra fitted from factory eg. exhaust, quick change gearshift, brakes suspension,cold air intake,chrome cam covers,It has done less than 3k miles which is ultra rare in the USA never mind the UK . Just to finish the picture it’s black with gold racing stripes . The car drives great so I am at a loss changing the FPCM or am I missing something ? The last thing I need is to mess around and get more problems. Any good tech’s out there would appreciate some input ?

 

Step one would be finding someone to undo what this hack did. Then tackle the original problem. I share Houtex’s frustration at this “repair”.

 

Agreed I would be finding someone who can undo what that guy did and start from scratch. I know its frustrating but that probably what would be best.

 

This right here is why we're saying take it to someone reputable and pay them to fix the hack job and then do it right. That's the input. I hope that doesn't come off too harsh, or actually harsh at all, but the reality is what it is. We're waaay over here. Even if this was in the states, we'd be saying the same thing. Sometimes you gotta pay the man/woman.

The alternative (if you don't have this 'world' of stuff in your bag of tricks, mind) is for you to get a proper shop and wiring manual (Here's one, but I can't vouch for its completeness and it's not necessarily for conversion/European models, and it's for a 2011 which may not apply completely either) and some electrical tools such as a soldering iron, shrink wrap, nippers, strippers, butt splices, multimeter and/or power probe and get to figuring it out rightly. Maybe a few books/lessons/MePipe videos to learn how to diagnose and fix/repair electrical correctly and safely, both for you and the car. The manual will show you where things are, how to get to them (removing panels or parts as needed) and how they are supposed to be in the car.

I wish you good dang luck!

 

Thanks again for your time and suggestions ! Companies over here in the UK that do light conversions for American cars are few and far between I done my homework and went with the best reviews it was not about saving money ! the light conversion was done 6yrs ago when the car was new and because the car has not been used much the brake light problem was only picked up recently all the original work was neatly done using proper soldering joints shrink wrapping and relays etc .the problem was how he went about fixing the brake light which should have been a simple fix taking a separate in line fused 12v supply but instead because he was lazy and clearly wanted a quick fix he took it from the FPCM ! He has admitted his mistake and agree’s with everyone’s view that it was a dick move to cut corners .obviously now as the trust issue has broken down I would prefer any more work done to my car to be with someone who doesn’t take risk’s with my car . So going back to my fuel gauge not working as it should could be down to replacing the FPCM that he clearly mucked up or would it run deeper and maybe the senders ? Appreciate all views

 

Alrighty. Beyond that wirin'.

Has the FPCM wiring been fixed back to stock? Or no? If not, then that first. Matter of fact, all things fuel tank/gauge/boxes wired back to stock would be my call.

If that's been done, then diagnostics are in order. You'll want the shop manual and wiring diagrams regarding your car and some tools, as I expressed above. Or a person who has all that. Once those have been procured and you or they have done the diagnostics, you can then properly fix it. Which may include, yes, a new FPCM. Or *may not*, and that's the key. It could be something else, and us guessin' from anywhere but at the car with those diagnostic tools is a bad thing to listen to.

There's really not much more that can be done here, to be honest. That conversion is not an every-Mustang thing. That it was done incorrectly makes it worse, and therefore you really are on your own and either need to learn the craft of this diagnostics and wiring (and therefore be a new guru in the field of American Mustangs in Europe!) or you need Edd China. Or maybe those guys at Car Throttle, they seem quite good too. Here in the States I'd say Eric O of South Main Auto, you can pay him all day to figure this out, and he has the resources. He won't like it, probably, but if he takes on the job, he'll fix it. Such like that, but maybe not MePipes or TV people in actuality.

There ya go. I'd rather you did that than just buy an FPCM and it not be the thing... or worse, the problem fries the new FPCM and you're not better.

Crossin' my fingers you get it sorted. Good luck, and please, report back when you got news!