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Old 08-18-2013, 11:20 PM   #1
Scooby Specialist
Member#: 337170
Join Date: Nov 2012
Location: hesperia, California
2003 wrx

Default DIY FIX: ECUflash " programming voltage too low"

So, i have been flashing for quite a few months now. Recently i started getting this code "programming voltage too low" and it would not go away. i tried everything like reinstalling ecuflash and all definitions, converting files from 160k to 192k, saving the file extension as .bin and .hex, resetting the ECU, and searched every single post on google about it. Every single answer i got from any source was either incorrect or very very vague and hard to grasp. So i am here to make things simple for you garage tuners.

a little background on the problem: for some reason, where your reflash connector on the "flash block" goes, can drop to around 4v or so out of nowhere for an unknown reason and cause this to happen. wether or not your car battery is fully charged will have no impact on this. you can find some solutions on the web but like i said earlier, they are NOT easy to understand and are not explained at all.

how to fix it: well, all you really need to do is find the wire thats putting out the 4v of power and make it put out 12v. now wait, i know you're probably asking how the heck you do that? well if you are using a 2003 wrx then i've already done it for you! if you are using a different platform than all you need is a multimeter and touch each pin in the flash block to find which one is putting out 4v. here is a picture illustrating the 2003 one (its the only red/white wire on the cars harness) but this is the picture of the reflash connector, you get the idea.

now, the easiest way i found to get a switched 12v to that wire would be from the cruise control plug. this would be the green/black wire as shown in the picture. to get it out, you will remove the ask tray deal so you can see the fuse panel. shove your hand up in the hole (say what? ) and then push on the cruise control plug and it will pop right out.

you're going to jump the green/black wire from the cruise control plug to the reflash connector. i just soldered mine but you can do whatever you feel like doing depending on your skill and resources. i simply ran the wire behind the panel which was as simple as could be, and plugged the reflash connector back in.

that was easy, right? well you're not done. just as ecuflash can display a voltage too low problem, it can also display voltage too high and you're right back to where you were and unable to reflash. now, if you have done the ground mod like i have, that connector is getting a whopping 13-14 volts. that needs to be toned down to 12v obviously so turn on the headlights and a/c fan to drop that voltage to the working threshold that ecuflash wants. if you do not have the ground mod, you probably dont need to do this. you are now done! happy reflashing
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Old 10-03-2013, 05:45 PM   #2
NASIOC Supporter
Member#: 236475
Join Date: Jan 2010
Chapter/Region: BAIC
Location: San Francisco
2002 WRX


I applaud your effort, but this is a really bad idea. The voltage that is coming out of the OpenPort is a regulated 12 volt signal which the ECU is using (and requires) for reprogramming. You do not want to be using an alternate unregulated voltage source to put 13 to 14 volts on your ECU. This is not a light bulb that doesn't mind a little extra voltage.

If I was to make a guess, it could be the connection in the reflash block has come loose and the 12 volt signal coming from the OpenPort isn't making it through to the ECU. Take a look at the following diagram and you can see that the wiring is pretty simple from the data link connector (OBD2 port), through that reflash connection (which I highlighted in yello), straight to the ECU. If you're not seeing the voltage you expect there, you should trace the circuit, not insert unregulated voltage in to the mix. It could also be that your OpenPort is no longer putting out 12 volts, but that would be pretty unusual.

If you test your connection and you find that it's the reflash adapter, I'm happy to ship you another. If your OpenPort isn't putting out the correct voltage, send it in and we'll take a look. In any case, you should remove that unregulated voltage going to your ECU.
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Old 10-03-2013, 08:59 PM   #3
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Member#: 267815
Join Date: Dec 2010
Chapter/Region: South East
Location: LSx allll done..need headers
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Worse case scenario would be a faulty ecu. (Although I highly doubt the ecu has a scetchy output driver because reference voltage supplied from the ecu is either 5v or 0v. Ive never seen anything other...It IS HIGHLY possible that your 5v supply wire may have became corroded over time, could even be several small strands of wire inside the insulation broken. So........run a new wire from the ecu to the block. We have wires with unwanted resistance all the time at the shop...a dealer mind you.....we use whatever size terminals and wire specified and make it new again. Standard operating procedure. Use the schematic above and a DMM to find the area of unwanted resistance then correct it ......(repair the connection or replace the wire....hell id do both once I found it lol
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