Resetting EZ210K

Robou · Post by **Robou** » Wed Aug 20, 2008 6:55 pm

Actually it isn't resetting we do, it is emptying the Random Access Memory in which the ECU stores bits that make it remember occurrences. Some of this memory we want to get rid of, when it makes the ECU act in an undesirable way.

Common practice is to correct some settings, disconnect the battery ground for about half an hour, and try again. Impatient people then have to go through the whole procedure again, because they reconnected too early. Some people say switching the ignition key on in the meantime helps, other claim benefits from connecting the battery clamps. Mind, at disconnected battery!

When the ignition is switched off, power supply to the ECU is switched off. How come this memory is conserved?

The IC's in the EZ210K are marked by Siemens with numbers that can't be traced by ordinary people like us. The microcontroller is clearly based on an Intel chip, because their name appears on it. The 8051 from Intel jumps into mind and checking for something like it with Siemens leads to 80515, of which the pin layout is very much like used in the ECU.

The first designs of the chip, from before 1995, indicate pin 4 as VPD, probably Voltage Power Down, from which the on-board RAM will draw power, about 1 mA, when the main power supply voltage has a lower value. It now happens that this pin 4 in the ECU is connected to a 10 microFarad tantalum electrolytic capacitor, marked C505, and this leads to the conclusion that it's charge is used to keep the RAM alive.

Discharging the capacitor indeed emptied the RAM. Bingo!

A 1 mA current discharges the capacitor as well, at a slow rate. So how come the RAM keeps it's values forever when the power supply is shut off by the ignition switch? I don't know, didn't get into it. Probably by some leaky circuits taken into account by the designers. But I was not interested enough to find that out.

Discharging the capacitor of course can be done by just shortening it, but I think it is advisable to use a 1KOhm resistor in series. If one forgets to switch the ignition off the current drawn will not harm anything, I suspect.

Good practice is to solder a lead to one side of the capacitor, a 1KOhm resistor to the other side, a lead to the resistor, extend the wires outside the ECU and, ignition off, connect the wires by means of a push-button switch.

Don't blame me. Yknot asked for it.

Ettore Bugatti · Post by **Ettore Bugatti** » Wed Aug 20, 2008 7:09 pm

Thanks! That's very intresting

I assume that this could cure the boost problems some people had with the R207 mod?

Robou · Post by **Robou** » Thu Aug 21, 2008 6:43 pm

It doesn't cure anything, it is just a quick and easy way to "reset" the ECU, which in turn doesn't cure anything either, it just frees the ECU temporarily of erratic behaviour triggered by its build-in safety margins.

Instead of random changing and/or cleaning parts in case of trouble or even before changing anything with the engine I advise cleaning up the RAM and be aware at what triggers the undesired situation again. It helps to pinpoint the real cause, which sometimes seems to have nothing to do with the symptoms.