Can anybody tell me what the little hole in the jap spec ecu's is for? It has a small label above it and the hole is covered by a clear film but after spending 3 hours on some google translate site i still cant figure out what it says!!! On stripping the ecu it looks like a very small variable resistor. I am only curious to know what it actually is rather than having any mad urge to go messing with it...lol. ecu is from 92 k11, very early model. We have a few of them lying around and its bugging us now to find out!
Jap ecu query
- Thread starter Lord Lucan
- Start date
OP
OP
Funny that because we have a box of ten ecu's accumalated to be used as control ecus for the particular class i race in. Most are bosch examples and i opened a couple to compare with the JECS ones, the bosch examples did not have this little gadget fitted. Its really a case of not wanting to hand out an ecu that may have a certain feature in it that may give an advantage (not saying that it even does anything to begin with)
Frank mentioned about being able to read fault codes of an led on an ECU a while back maybe that's what it is?
OP
OP
Both bosch and jecs have the LED fitted, i did wonder that but without information being readily available its hard to know
OP
OP
The only words i could translate after 3 hours was CAUTION and TIME....they have a very complicated language indeed
OP
OP
Nah, mine has the LED
View attachment 26668
Bosch ECU, but most of the chips are JECS.... only actually 1 Bosch chip in there (and 2 Mitsubishi ones).
Could be to adjust the data sampling rate...
Maybe, the gadget im talking about is located between the black and the blue dudes on that board, has a tiny phillips head adjuster on the top of it
OP
OP
frank
Club Member
maybe a 5 position diagnostic mode switch ? http://www.troublecodes.net/Nissan/pre88nssn/
Enuo
Glorified Electrician
No, it even says variable resistor on the board where it should go... definately for a variable resistor and definately goes to a capacitor. Putting a resistor in front of a capacitor is to change charge and discharge times of the capacitor which usually means its for frequency control.
Must be the flux capacitor then 
That small piece on the PCB is called a Trim / pot, bit like a volume control you get but designed for PCB for fine tuning which ever value is needed to do what its there for..
I reckon if you adjust it the car may up the BHP more fuel????
Joke!!! I wouldn't touch it unless you know what its really meant for!! OR to be adventurous get a multimeter and touch the terminals and see what value its set at and write it down , then for some adventure turn it up alittle and see what it does, if nothing or running erradic then turn back down to the original setting!!!
Pain or knowing is over!!
J
I reckon if you adjust it the car may up the BHP more fuel????
Joke!!! I wouldn't touch it unless you know what its really meant for!! OR to be adventurous get a multimeter and touch the terminals and see what value its set at and write it down , then for some adventure turn it up alittle and see what it does, if nothing or running erradic then turn back down to the original setting!!!
Pain or knowing is over!!
J
Enuo
Glorified Electrician
The LED yeah, the potentiometer not so much
Enuo
Glorified Electrician
Nah, already established it's for controlling the frequency of something...possibly the ecu clock
Enuo
Glorified Electrician
Again, that's the LED. If it was a switch with a discrete number of positions then I could imagine that it might possibly switch between fault reader settings, but seeing as the object in question is an infinitely variable component, this is almost 100% not the case. As I pointed out before, where you have a varying resistance to a capacitor, you are altering the length of time that capacitor takes to charge. That is how you control the time before the voltage is high enough to activate logic circuits inside the chips etc, dictating things like operational frequency of the chip or signal output durations etc.
frank
Club Member
but turning it fully clockwise is basically shorting the 2 pins out tho innit ? http://www.ebay.co.uk/gds/How-to-read-clear-Pre-1994-Nissan-fault-codes-/10000000002347040/g.html
Enuo
Glorified Electrician
Why would they not use a simple 2 position switch then, cheaper than a POT.
frank
Club Member
softer/less spiky shortout maybe ?
Enuo
Glorified Electrician
I reckon something like early supply issues of the chips they wanted meant they had to make do with a different chip with a slower max operating frequency, so for the first few before supply issue was resolved they made it so they could manually drop the frequency, then after the supply issue was resolved they went to a fixed resistance.
OP
OP
I think your spot on there, i cannot find any other possible explaination other than what is in that thread.
