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2003 ford fiesta shows EAC FAIL warning light
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gcowie
New User
Sep 20, 2010, 10:40 AM
Post #1 of 2
(8191 views)
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2003 ford fiesta shows EAC FAIL warning light
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My 2003 Ford Fiesta 1400 petrol engined car has an erratic but persistant warning light fault. It occasionally indicates "EAC Fail" The hand book explains this refers to the electronic accelerator control, and once this warning light is on, the engine reduces in power but still allows it to be driven up to 18MPH. However, if the car is stopped and the ignition switched off then on again, the warning light is off and the car drives normally, sometimes for months. The throttle body was changed by Ford on warranty but now at 46000 miles the problem persists, sometimes appearing once a week, sometimes after months
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Sidom
Veteran
/ Moderator
Sep 20, 2010, 11:29 AM
Post #2 of 2
(8182 views)
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Re: 2003 ford fiesta shows EAC FAIL warning light
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I'm not familiar with non-US models but it sounds like you have a "drive by wire" system. This system has no mechanical throttle cable and is totally electronic. It uses 2 TP sensors (throttle) and 2 APP sensors (gas pedal, some Fords actually use 3). The voltages are staggered. One set the 1st sensor voltage is low and goes high, 0-5v , the 2nd sensor voltage starts high & goes low, 5-0v. The other set's voltage are staggered by 1v. One starts at 0v & goes to 4v the other starts at 1v and goes to 5v. (these arent the actual voltage specs but makes it easier to understand if you aren't familiar with the system)
The reason for this is safety if one sensor fails or gives an incorrect reading the comp doesn't know if you want a little gas or full throttle. That being the case, if there is any doubt you get almost no throttle until everyone can agree.
With just one sensor on the system and it failing. Things could go very bad if you just gave it a little throttle and the PCM thought you wanted full throttle and gave you full throttle......
(This post was edited by Sidom on Sep 20, 2010, 11:31 AM)
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