Hi all Does anyone know what sort of signal a Mk4 tacho expects? I'm trying to get on to work with a DTA ECU. I've had a scope on it, and it appears to be a 5v square wave, but the "off" is at 8v, and the "on" is at 13v. Our standard 12v square wave doesn't work at all.
its the same signal as the mk3 golf rev counter signal if thats any help, plus digifiz, later corrado/passat etc. what pin number and what ecu are you trying to scope?
Hmmm, that's what I thought. We're scoping pin 6 on the Bosch 80 pin ECU as it's an AGU. It's the correct one, as we can see the pulse width changing with RPM, but when we connect our output to that pin, the tacho isn't responding. Just a thought. Does the pulse width change with constant frequency, or does the frequency change?
yep thats the one, just thought it was worth double checking so is this in a mk4 golf then? its possible the clocks are expecting a can-bus signal, I'm not 100% if the later clusters will read from both simultaneously or if they will ignore the tacho pin if coded to read the can-bus? This post suggests that without can immo3 clocks revo doesnt work: http://forums.tdiclub.com/showthread.php?t=415361 Anyway to check this out if you go into the clocks with vagcom look at the service interval/cylinder code. Possibly if you set 0, 1, 2 or 3 that puts them into 'canbus' mode and 4, 5 and 6 puts them into 'ecu pin' mode? From http://www.ross-tech.com/vag-com/cars/vwmkIV.html To change features/coding go into vag-com instruments, then click 07-recode Instrument Cluster Soft Coding xxx ? x - Service Interval/cylinders 0 = fixed Service Intervals (PR-QG0) without Oil Level/Temperature Sensor 1 = flexible Service Intervals with Oil Level/Temperature Sensor (PR-QG1) 2 = fixed Service Intervals with Oil Level/Temperature Sensor (PR-QG2) 3 = without Service Intervals (2002+ models) 4 = 4-cylinder (1999-2001 models) 5 = 5-cylinder? (1999-2001 models) 6 = 6-cylinder (1999-2001 models) or it might just be the rev counter wire to the clocks isnt even there in the later mk4 loom, can you check the clock plugs to see? blue plug pin 11. It will be there in the main car harness as its still needed for climatronic
I sold my VAG-COM cable years ago. I'll have to borrow one. I was working on the assumption this is IMMO2, as it's an early 2000 car.
Turns out there are two version of the dash. This one is CAN based. We've worked out the CAN packet IDs for the RPM. [video=youtube_share;pKWOZRaCiao]https://youtu.be/pKWOZRaCiao[/video] Now to write some custom firmware and put it back in the car to see if it all works. I suspect we're going to need to find some more CAN bits, as the oil pressure light is currently moaning at us as well. Then plug it all in to an older car, and see if that works too.
Nice! Did it have the oil level/temp sensor? I'm thinking maybe CAN clocks are down to that, rather than age...
There are 4 different types of ECUs from the MK4 1.8T. M3.2, M3.8.3 ME7.1 (ARZ) and the ME7.5 (AUM, AUQ etc). Early AGN/AGU cars had no CAN. Hardwired only. AGU M3.8.3 400/200BB flashable cars had CAN messages shared between cluster and ECU and this library became greater with the Egas vehicles. Oil switch is hardwired with the cluster even on later cars.
Thanks Eddie This is an M3.8 Golf, so has CAN. Dashboard is now working, so a base map will be created next week. This means we can finalise the design of the adapter now. Oil pressure warnings are tied to the CAN. That's fixed too. I also have the ME7.5 Passat which should work with the same CAN messages. That's the next test. I presume the difference between ME7.1 and ME7.5 is cam control, among other thing? ARZ doesn't have variable cams, but AUM/AUQ do.
Do you know how to put digifiz rev counter working properly in a MK2 GTD, since that the rpm signal comes from the alternator?
you'll need an alternator W terminal to low amp signal adaptor, this is the only one I know of https://www.dakotadigital.com/index..._id=1192/category_id=-1/mode=prod/prd1192.htm
