(ECT and VSS work!) Yet another s2000 cauge project [READY]

Orthello · Post by **Orthello** » Mon Jul 28, 2008 9:18 am

I already had the whish for a digital cauge assembly for a long time. First wanted to fully build my own cauge, but at the end desided to go for an S2000 MK1 cauge which I bought for not to much money. I was aware of al the shit going on with VSS and ECT signals, but experienced this as beeing a challange to go for. With some basic electronics knowledge Is started to investigate what the S2000 cluster was expecting wrt VSS signal. It turned out to be a 0~5V 50% square, but... at 36 times the rate of an EF VSS. So I started thinking how to do this. F/V -> V/F converter could be an option. PLL with a pulse divider could be a second option. I decided to go for a microcontroler solution because it was likely that the ECT signal should be changed too. And that could be done by the same microcontroler, which keeps the hardware simple, and also makes it possible to change things, without changing the hardware. So I started to learn myself how to deal with microcontrolers. Then at some point a gave a shot and tried to get some readings on the S2000 cluster. Damn... that worked! Way cool. But... this was just a fixed pulse rate without an input pulse. So.. I went further. Took an old VSS (which used to be mounted at the back of EF cluster) and connected that one on the input of the microcontroler. Changed the software a bit and.. YES.... readings which turned out to be pretty nice and lineair too. So... connected the breadboard and S2000 cluster in the car. Nothing. The microcontroler didn't even start. So back to the workbench. After some extra reading of the microcontrolers documentation it turned out to be three additional connections I had to make. MCLR shout be kept at 5V at all times. And also the secondairy +5v and ground should be connected. So I did and went back to the car. The microcontroler started and sustained. Now let's see if it is able to receive VSS signals. Oh yes it does!! SWEET... let's go for a spin... Damn... everything looked fine.... until I passed 30 km/h (19 MPH) then the readings on the S2000 cluster were bogus. But.... the trip readings were more or less fine after a 2 km (1.5 mile) test round. So... this was a start. Well time and testing went by. Yesterday I tested a changed version of my hardware (Added some capacitors to filter noise) and was able to measure up to 130 km/h (80 MPH) It's a pretty nice result and could be a final version as in holland we are not allowed to go faster then 120km/h (75 MPH) But.... we all know....

Ok.. the fact it is'nt able to go higher then 130 km/h (80 MPH) and I filtered the noise made me deside to have a scope measurment of the signal. And then it became quite clear wat was going on... still noise... but not normal noise. The noise was only there when the VSS was in 'make'. In that state it connects itself to the ground. Remember ground!! Ok... know a little side step. Because I want to be able to get the cluster in and out the car very easy I used the cigaret lighter to supply the power to the cluster and my converter. Also the ground of the lighter is used to do so. That is another ground. Ok... so I went thinking... VSS only suffers noise when connecting to ground. Ground for power is at another place. Damn.... that must be a ground-loop. I'm wasn't able to test it yesterday, but I'm going to test it tonight. I'm going to relocate the the power lines to the back of the EF cluster and use the same ground as the VSS is using. So.... to be continued. Man... I'm so keen to produce my own converter and save myself more then $100 !!! Ok... if the ground-loop IS the problem... and it solves the readings... then another challange is there.... ECT. Rumors say it's a PWM signal. But I don't have a single clue yet what frequency is used, nor do I know the Duty Cycle. So.... the thing should be connected to a function generator and have to undergo a lot of torture to atleast get A reading. Tips, tricks and hints are welcome! Ok... that's it for now.

CRX2 · Post by **CRX2** » Mon Jul 28, 2008 1:25 pm

The ECT and IAT sensor look just like normal resistor types. However...The ones I found in the ESM are for the ECU, not for the gauge.... The \"ECT meter\" signal is an output off the ECU. So it can be all kind off signals... I2C, Dutycycle, analog, etc... The easy way is to borrow a S2000 and put a scope or analyser on the ECU...

Orthello · Post by **Orthello** » Mon Jul 28, 2008 6:23 pm

Well... fixed the ground-loop.. but no result. Went for a spin. When display went bogus, turned the off the engine (key in I), but kept rolling. Readings were very accurate now. Turned the key into II without starting the engine. BOGUS!!! Looks like de ECU is causing trouble. Because without the engine running, there is no noise from the alternator or distributor/coil. ECU and test elektronics are more or less stacked on top of eachother when testing. Tomorrow morning I want to do a retest with the ECU and conversion elektronics as far away from each other as possible. If this does the job...Ihave to figure out how to get rid of this interference. Also did some ECT testing. Walked form 60 to 4000 Hz with 50% duty cycle. No result. Only an empty or full reading. Nothing inbetween. Als did a 0% to 100% duty cycle test at 60Hz. Again only an empty or full reading. Nothing inbetween. Figured out that the refresh rate of the ECT display is exactly 30 seconds. But that's it for now. To be continued.... @CRX2... where to find an S2000 to play with????

Would 'Borghstede' be so friendly?

JaredKaragen · Post by **JaredKaragen** » Mon Jul 28, 2008 11:18 pm

I thought those were a serial/TTL data connection for the gauges....

Orthello · Post by **Orthello** » Tue Jul 29, 2008 3:32 am

That would only be for the ECT then, because all the signals are as it used to be. Only VSS (which is around 36~39 times faster) and ECT (don't know yet what kind of signal) This morning took the car for a spin to test if EMI would be the problem. Still could be, but putting the ECU/Ostrich away from the conversion electronics didn't fix it. And I'm sure it is the ECU (or maybe coil) is causing this behaviour. Because.... I was driving 130. Turned the key to I, while keeping the engine running (because of the momentum of the car) This way I still have alternator noise, but no ECU or coil activity. Readings were fine. So the alternator isn't the problem. ECU (and maybe coil) are remaining as possible culprit. Tonight or tomorrow I will do some extra signal plotting with the scope. Hopefully this shows what happens. Also found that the VSS input is only triggered by a rising edge. This makes it possible for me to test different ways of frequency multiplication using a microcontroller.

JaredKaragen · Post by **JaredKaragen** » Tue Jul 29, 2008 3:40 am

Yeah, I think it's some sort of logic data going into it for it's reading; I remember the website form the guy that did it years ago and was offering to convert and zero out mile son clusters... can't find the link though. But yeah, ECT and tank are the 2 that did not read properly correct?

Orthello · Post by **Orthello** » Tue Jul 29, 2008 3:51 am

You're talking about Mark Lamond from Scotland/GB? I tried to get in contact with him about this conversion, but he isn't telling anything. No wonder... he's offering a conversion service and making money with that.

VSS (speed pulse) and ECT are different. Al the rest remains as is. Fuel is the same signal (0~100ohm resistor type sensor), but because of the different shape of the fueltank it can have a different curve. But apart from that it's the same signal.

CRX2 · Post by **CRX2** » Tue Jul 29, 2008 6:40 am

VSS is an old fashioned VSS-sensor. Not a ECU output like the ECT sensor... How do you put the VSS signal to the gauge? Direct? You could try with a Schmitt-trigger (HEF4093 I think...) and \"clean\" the signal from spikes and noise. And also check your supply voltage for spikes. And don't forget things like pull-up of pull-down resistors. The PIC?? processor has a very high input resistance.

Orthello · Post by **Orthello** » Tue Jul 29, 2008 8:27 am

I'm not sure yet where the problem exactly is. Can be input, can be output. Need to do more scope measurments to take any conclusions. The way the VSS is working (connect to ground) was also a point of my concern. Currently it's not setup the way it should. It should connect to ground, but currently I'm just providing a 0v or +5v signal to the cauge. On the bench it works and in the car it works too.... until the ECU becomes active. Alternator noise is no issue. Tested that already. S2000 VSS signal is a 'digital' signal. It is a 0~5V square ranging from 0 to 7kHz I used pull ups to have a nice 0-5V pulse from the traditional (reed type) VSS. Output of the PIC is directly connected to the cauge. No resistors, no capacitors, no nothing. Just a simple, single wire. And again... on the bench it works. In the car it works... as long as the ECU is 'dead'

Orthello · Post by **Orthello** » Tue Jul 29, 2008 2:32 pm

Spy movie!!!!!

Post by **nate** » Tue Jul 29, 2008 11:21 pm

Awesome!

ge0ne · Post by **ge0ne** » Thu Jul 31, 2008 4:14 pm

I am interrested in a converter like this for my car... I have an S2K cluster sitting im my garage with its harness...

JaredKaragen · Post by **JaredKaragen** » Thu Jul 31, 2008 10:28 pm

I have been wanting to do the conversion... but when I sent emails before to MArkLamond; I never got any responses from him about pricing and turnaround time so I gave up.

Orthello · Post by **Orthello** » Fri Aug 01, 2008 5:12 am

experienced the same with mark when asking vor technical details.

CRX2 · Post by **CRX2** » Fri Aug 01, 2008 8:32 pm

Did you look on pgmfi.org? A very long time ago he was asking things about S2000 clusters. Must be three years ago or even longer...