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p0456 and p1246

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Paladin

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Discussion starter · #1 ·
well my car is doing both as of this morning leaving for work.
p0456 is a small evap leak code. i replaced the fuel filler cap about a month ago and it went away, now its back. what gives? is tehrea peurge valve somewhere that may be totally shot now its original to teh car if it is, i haven't messed with any emissions stuff related to teh fuel system.

p1246 says my alternator load input failed. whatever that means. can someone elaborate on this?
the alt was replaced 2 years ago after the first one packed up on me. i repalced it wit ha new one from ford. only electrical system mods i have are a braille lightweight battery in an omnispeed battery mount and 4 gauge wiring for grounds only , along wit ha sub and amp. no capacitor or anything as those can damage stuff. car runs and drive fine. but this second code worrys me. so what and where should i start poking around underhood. i will ahve to borrow a digital multimeter as i dont ahve one. but i doubt teh battery is a suspect as it starts the car just fine, and has been in teh car for 2 years without an issue (installed the summer after teh alternator died)
 
#2 ·
Alternator load input is a signal sent to the ECU from the voltage regulator built into the alternator. The ECU uses this signal to figure out how much load the alternator is placing on the engine so it can make rapid changes to the idle air control valve to maintain a stable idle speed independent of varying charging demands. The signal is varied by alternator temperature. The higher the temperature the higher the load but the signal is actually a duty cycle or frequency instead of a voltage.

I would connect an oscilloscope to pin 1 of the alternator pigtail (grey wire) or pin 59 on the ECU connector and see if there is indeed a duty cycle signal present. If no signal is present you either have a bad connection, a break in the wire, or a bad voltage regulator which means alternator replacement time.

Good luck.
 
#3 ·
Also, check fuse number 10 in the engine fuse box. It should be a 10A fuse.

Sent from my SCH-I545 using Tapatalk 4
 
Discussion starter · #4 ·
i can check fuse ten. but the car operates normally. and in fact i drove it to work (cel went off in my driveway leaving for work at 4 am.) it hasnt once skipped a beat. so i'm thinking it may be a loose / old and bad connection i ahve to track down. i dont have an oscilloscope to properly check.

and ideas on teh evap code?
 
#5 ·
My personal guess is loose connection followed by a failing voltage regulator. Luckily the load input signal is going to have very little effect on the operation of the car. In fact you could probably cut that grey wire and never notice a difference if it weren't for the MIL.

As far as the evap code goes I can't help much. It could be the evap purge valve on the firewall, the evap vent valve at the fuel tank, fuel tank cap, and/or any of the evap hoses.
 
Discussion starter · #6 ·
well its given me some places to start looking. my guess is i should look at the pigtail for the alt and see if i ahve a bad wire. its a start at least.
 
#7 · (Edited)
So a stock alternator with an undersized battery and a big stereo? Very possible the alternator is packing up again because it's likely being overworked.

Those Braille batteries have their uses but from what I've seen they don't do well in DD use.

You might also check any aftermarket wiring for corrosion in the cables and/or loose connections.
 
Discussion starter · #8 ·
^^ that's my thinking. i think when i demo it (because it sounds great) i always have the engine running but it may still not be enough. looks like i'll be swapping a big optima in teh factory box. shame though because i love teh omnispeed mount. i'll save that for a second focus. or weld it to my rear strut brace so i can have a dual batt. setup.
 
Discussion starter · #9 ·
welp a code came back the very next week, lol its that evap code. now i've already replaced my fuel cap. and i do ahve a bit of a crummy repair on a vac. line to teh purge solenoid thing on teh firewall (if that's what it actually is its behind the power steering res.) bu i checked for leakage ther and everythign seems pretty darned tight. i could replace teh whole hardline with a proper sized length of universal vacuum line right? ive checked the fuse for the evap system and its fine so i guess the enxt questin is where to look. the whole system is original to the car (as the stuff is similar between models) the cel kinda bugs me. but at least i know what it is. i just dont want to keep having to turn it off with a scan tool every other week. so i guess i need to know how to check an evap purge solenoid, and then see if any of the fittings have gone bad.
 
Discussion starter · #11 ·
^^ yeah dont think i can find a junkyard svtf to get that line. as its taht stupid hard line. i'm going to replace that whole little hardline with a rubber line its teh only way to be sure i fixed it the right way. 9the line is discontinued, plus most of them will morethan likely shatter if i pull one.
 
Discussion starter · #13 ·
well i fixed it. turns out my little busted line was not teh culprit. i had failed to hook up the large line that goes from the purge valve back to teh tank. didnt slip the connector on teh metal pipe far enough to properly seal the system. and woudl therefore get a leak code everytime a large temp. sjift occured. silly me forgettign things.
 
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Paladin
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