Jeep xj Tdi alh swap how to get tach signal

Hello, Im swapping my 1998 jeep Cherokee's 4.0 for a 2003 ALH Tdi. Ive ran it and drove it and just have to finish a lot of little stuff. One problem I'm working on now is getting tach signal to the stock xj gauge. I know I need my jeep cps but have heard I also need a momentary 5v signal from my cam but can't find any specific info on how to do this. So any ideas on how to get that signal would be highly appreciated.

Have you contacted dakota to see if they make something to interface between the vw ecu and the jeep gauge? Their stuff tends to make a tach signal nearly plug and play in many applications.

If I had to figure it out myself:
Figure out what the Jeep tacho uses as signal.
Figure out what signal the ALH magnetic pickup (called G28) sends.

Then the hard part, find a (cheap) way to convert from one to the other.
Or, find out what the ALH ECU outputs to the VW tach, and convert/modify that signal.

I'm "almost" positive I use the standard DD tach box to take the Jeep CPS signal and feed it to the cam signal wire in the Jeep ECU.

Ok ill try that evguy and see what I can come up with. Thanks!

I found a old thread from a guy building a Tj Tdi and he was talking about just wiring the crank signal and the cam signal on the Jeep together but he never posted back and that was 4 years ago does anyone have any input on this idea. I guess y’all can tell I’m not a electrical genius. I just don’t want to fry my ECM.

Get a hold of Jeddadeezl. He got his tach working on his 01xj alh swap. He is going to document it really well soon. Also are you following his bleepinjeep build?

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The ALH ECU has a tachometer output. Pin 27. Standard 2 pulse per revolution 12V square wave.

Some tachometers need a 12V with a "spike" signal, that came from the ignition coil that used to drive them. Older Toyota / Volkswagen / Suzuki are all this way. But the 98 Jeep should be. If it was my $US40 "Hasenwerk Digital to Analog Tach Converter" would do the trick.

It is my understanding that 1998 and on Jeep, the instrument pod uses Chrysler's CCD protocol to run everything. Codi Built black box is needed - these are somewhere in the US$400 ballpark.

So Hasenwerk your saying that if I bought your analog signal converter I could connect to my tach signal wire that is on my stand alone wiring harness for my alh engine and then run to the cam signal wire on my jeep and should be all good or am I confused.

I have my cps installed on my stock jeep ax15 and can start up my jeep and turn my old 4.0L cam sensor for my jeep one full turn and thats all it takes for the tach to fire up. The ecu on the jeep is basically wanting cam signal just to verify that its running and just the one turn is all it takes

On a swap that I did a few years ago (crap, probably more like 20 years ago) I just used a NO relay connected to the starter wire. When you cranked the engine the relay closed across the cam sensor wires ( no actual sensor) and sent a pulse to the ECU. That was enough to wake up the ECU. When you stopped cranking the relay opened back up.
Worked for years and cheap.
Try just shorting the sensor wires while the engine is running and see if it works.
Let us know if it works or smokes something. ;>)