I didn't earth under the plastic bolt shroud - i earthed to the top of it and since clearing the codes i've had no return of them and no other problems.
Given these possible problems with the unit (before I install mine) would there be any benefit in installing it somewhere else i.e. further away from this ABS module and ideally any other modules/looms.
Are people having the problem from just providing bad earths?
Yes - it came back this morning. However unlike Mat and Skahigh i won't be removing the box simply because of the price involved in replacing the fans. The ECU can report all kinds of hokey errors and this is just one more on top of a whole host of other things that can appear without rhyme or reason.
I am also thinking of cutting the low speed fan wire, if the resistor has indeed blown then I wonder if something is 'bleeding' back down the wire and causing a resistance change elsewhere on the loom which the ECU is misreporting as a glowplug fault.
Either way the box fixes a problem for 85 quid that would cost 400+ from a dealer and which WILL break again - if the cost of that is an occasional fault code scan / reset using vagcom ( which i already have) then i'm prepared to live with it. It's replaced the occasional EGR warning that used to appear which has now mysteriously gone.
I can see your point Fester, my problem however is that with the nime box fitted my abs actually wasnt working, my mechanic brake tested it at relatively low speed and got the wheels locking up with lots of smoke.
I havn't tested the abs thoroughly since I removed the box because I am still bedding in my brake pads but I did some lighter tests and the abs did appear to be working.
From a personal point of view at this point I would rather have a known problem that I know how to fix and how much it will cost than have an accident because my abs doesnt work. Besides, the fans cost less to replace than the abs control module does.
The additional errors I was getting to do with the engine control module were also more than a little worrying.
I know I've posted this before, most recently in skahigh's other thread, but maybe not in this thread.
The Nime Box looked at in isolation, is an elegant motor speed control solution, consumes less power (so doesn't get hot) and is tested and proven to work outside the car.
Once you put it under the bonnet, it has to coexist with all the other electronics in the car.
The way the Nime box works is to reduce the power (for the low-speed setting) by switching the power on and off twenty thousand times a second. It feeds this pulsed power to the fans through the power wiring, which is expecting to see a 12Volt DC level, not 20KHz 12V square waves of 6 Amps. When the full speed relay closes, this pulsed signal is applied to the 12V lines all over the car, although there will be almost no current drawn so the size of the signal is very small.
The 12V power wiring is not screened in any way, expecting to see a constant 12 Volts. Applying any signal to it, even a small one, gets that all over the car.
It seems to work well in Mk.IV Golfs, the designer says there are quite a few running about and no big problems have been reported.
The original MkIV forum thread on fan failure first inspired the resistor mod, replacing the resistors that have burned out in the fans with external resistors on a heatsink.
Resistors are passive components. and you will just be fixing the broken bit rather than replacing the whole unit with a little broken bit stuck inside it.
MkIV forum thread
Fan autopsy
Resistor replacement (Golf, but process is similar for all MkIV derived cars)
I think VW have produced an electronic control solution, similar to the Nime box, on newer cars, however they have the resources to engineer a complete solution and test it in the car to ensure there are no side issues with other systems. My guess would be that the controller is close to the fans, and delivers its pulse-width modulated power over short wires paired with earth returns.