Tach signal

[evguy1]

Lets pretend I'm installing a 2006 BEW TDI into a 1998 Beetle with a gas engine.
What is the difference in tack signals?
The wire is the same coming out of the ECU, it all looks like the same setup but is the actual pulse / signal the same?
The truth is that this 06 Beetle is getting an electric drive system and I'm having trouble getting the tach to fire up.
I did a 1998 gas Beetle a few years ago and it was easy to get the tach to work. http://www.canev.com/beettleConversion.php
I don't think its CAN since it's a single wire for the tach.

 

[Hasenwerk]

The BEW engine doesn't have a tach wire that communicates to the instrument pod. This happens over CAN bus. Earlier MK4s with the EDC 15 did have a dedicated wire.

If you want a Analog tachometer 2CAN box for your instrument cluster, let me know.

 

[jimbote]

only the 80 pin mkiv tdi ecm's have a dedicted tach wire to the cluster....2000-2003 edc15 121pin do not have a dedicated tach wire to the cluster but rely on CAN to trasmit this data, ... however they do have a vestigial tach wire that transmits tach signal... in these cars the wire dead ends in the plenum chamber rainbow connector group ...can't recall what wire from the edc16 BEW emulates this but it may not be active as i have not tested it, but have built edc16 harnesses identifying the wire with "tach" followed by a big fat "?"

 

[Zeitgeist]

Ever so slight hijack...

How have folks configured the tach signal on mTDI swaps? In my case, I'm working with a stock Vanagon tach and an ALH.

Bonus hijack...

Would there be a way to trick the stock Mk4 cluster to work without having the ECU in the loop?

 

[Hasenwerk]

Ever so slight hijack...
How have folks configured the tach signal on mTDI swaps? In my case, I'm working with a stock Vanagon tach and an ALH.
Bonus hijack...
Would there be a way to trick the stock Mk4 cluster to work without having the ECU in the loop?

With no ECU to generate a tach signal, you would need a hall sensor that would monitor the crank. All TDIs have a crank position sensor, so with no ECU reading it, it would be free for you to use, you would need to calibrate that signal. My "VSS Korrekt" is an economical way of doing that. Cost for VSS Korrekt is $50

Now for the bonus to the bonus highjack, because you have a Vanagon, a straight Hall Sensor signal [12V square wave] won't work as your tachometer is expecting a signal from an ignition coil trigger. You will need one of these to format to something your unmodified tachometer can digest. These are $40.

There are two type of MK4 clusters. Early have more dedicated wires than late. Late get most of the information from CAN bus, like the tachometer signal. Fuel level, speed, coolant are all didicated wires. Fuel level is going to be backwards on your Vanagon as the senders are backwards. I am working with a fellow here in town with his Vanagon who is installing a MK4 pod and we will have the fuel level and speed calibration happening shortly.

All of these products can be seen here: http://fastforward.ca/signalprocessors/

 

[Zeitgeist]

Excellent response. We'll be in touch when I'm ready to tackle that molehill.

Luckily I saved the Mk4 fuel level sender, so I can probably graft that into place. My donor vehicle (and cluster source) was an '02 Jetta, which I assume is an early version.

 

[Hasenwerk]

Excellent response. We'll be in touch when I'm ready to tackle that molehill.

Luckily I saved the Mk4 fuel level sender, so I can probably graft that into place. My donor vehicle (and cluster source) was an '02 Jetta, which I assume is an early version.

One of the things I will do with this MK4 > T3 (and MK1/MK2) instrument pod adapter is make it so the fuel gauge reads correct with both Syncro and 2WD tanks as opposed to just inverting the signal. It will have a table of the resistances vs actual volume of fuel. When the gauge shows 50% you really do have half a tank. Fuel light comes on - you really do have only 10L of fuel remaining.

Early with a dedicated tach signal is normally the 1997 to 1999 MK4 stuff with the 80 pin ECUs. My experience with 1999.5 and later with the 121 and 154 pin ECUs that is that most instrument pod stuff is CAN. Some of these can be coded to make the tachometer work on a dedicated wire, some can not. Usually when people install these in their Vanagons they use the ALH / BEW computer so it all "just works" with the exception of the fuel gauge.

 

[Dorkage]

Tacho signal is on Orange T10 pin 9. green / brown.

No need for a converter. This signal is normally used for the climatronic, but if the car doesn't have climatronic the wire just ends in the cowling.

 

[evguy1]

It looks like my electric motor controller will put out CAN.
I need the[FONT=&quot] CAN ID and byte structure in order to program this.
Since the TDI is already out of the car I cant "sniff" the system to get this info.
Does anyone have this info?
I did find the green/brown wire and sent a signal down it with a signal generator but no wiggle on the tach so CAN is looking like the only way to go like David said.
This is a 2006 BEW and not the older ALH.
[/FONT]

 

[Dorkage]

Oh I misunderstood, I thought you were looking for a tach signal from a BEW ECM.

 

[evguy1]

My motor controller supplier was able to program the info into the controller and I now have an operational tach!!
So now that it has a tach signal I get an oil warning light. I assume its not a CAN signal and I can just fool the dash with a resistor across the old oil pressure sender wire.
I'll play with that tomorrow and then its on to the traction control system which has a warning light ON.

 

[xerootg]

CAN ID and byte structure

McNeil and I got a bunch of the CAN IDs reverse engineered and partially confirmed with a funkschramen. Check out the thread.

I'm using these with the CCD addresses I've figured out for my swap, if your ecu guy's deal falls through you might have luck with what we found.

 

[evguy1]

Thanks Xerootg.
The car is running, dash is working and should get deliverd to the customer the end of the week.
I should have started this thread a week earlier and saved myself more gray hairs.