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RAFALEE, VW Technician
Category: VW
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Jetta: epc light..keeps will go in to limp mood..100 miles

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the epc light on my jetta keeps coming on what does that mean. than it will go in to limp mood. If i shut down the car and reset it the light turns off but will come back on about every 100 miles. I just put a brand new battery and spark plugs in. please tell me what this light means. I do not have a owners manual.

Hi, EPC stands for Electronic Power Control. this means that your vehicle has a fly-bywire system, whish means that there's No accelerator cable and the throtle body is controled by the ECM (Engine Control Module). The Accelerator pedal (or gas pedal) it's just a sensor, so no mater what your input is on the pedal the ECM actuates the throtle how ever it wants. scary hu!!!, but have no fear, the Accelerator Pedal Module hoses two TPS sensors(Throttle Position Sensors), G79 & G185, this two produce an increasing voltage as you press on the gas pedal, but at diferrent rates for safety, the Throttle Body Control Module J338 (throttle body) also has two sensor G-187 and G-188, aswell as Throttle Drive Motor G186, G-187 and G-188 the output voltages mirror each other for safety reasons. back to your epc light, when you say reset it, do you actually clear the fault codes with a scanner, or you just cycle the ignition switch? either way if a fault for the brake light switch is present, this means most likely your problem is the brake light switch, some cases that brake light switch does not trigger a fault for still malfunctions and triggers an epc related code, i would replace the brake light switch, clear faults and test drive the car. so if you have anymore questions or if you can provide me with more info on the fault code numbers and descriptions, and if your vehicle is manual or automatic, please do, thanks...

Customer: replied 9 years ago.
manual, cycle ignition switch to clear fault,taken in to mechanic shop cant find codes
ok, if your epc light comes on there will be a fault code stored in the ECM, any generic scan tool will give a pcode(a fault code with a P on the bigining), cycling the key does not clear faults it only resets it self until the fault returns, is this a manual or automatic?
Customer: replied 9 years ago.
does brake light swich over ride throttle sensors
Customer: replied 9 years ago.
No it does not, what happens is that the ECM sees an incorrect signal from the brake light switch, for example it sees your pressing on the gas an at the same time your pressing on the brake, and it will get confused, or if you have a fault with a pedal sensor or a throttle sensor, have you had your brake light switch replaced? can you please accept i will continue to help you ,thanks
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Customer: replied 9 years ago.
no havent replaced

i would replace tha brake light switch first, it's the easiest and reletively inexpensive, if you could come up with fault codes it would be much help full, i don't understand why the repair shop say there were no faults, usually when an epc light trigers it stores a fault in the ECM, since it's part of the ECM, they aded another light ( the EPC light) because the Check Engine Light is more emmision related isues only, so in order to alert you of an Electrinic Power Control fault they aded a light, by the way, thanks for accepting.

Customer: replied 9 years ago.
thanks ill try that because your the only one that could tell me what epc was i wish i could find a progam for lap top like at work to read my car