I am trying to find the RPM signal for an external controller. I have purchased and installed a CANBUS interface with no luck. I also have t-tapped the crank position sensor wires, also with nothing registering on the controller display. My only other option is to tap into the common ground of the coil-on-plug unit for cylinder #1. I will try that today. Are there any other options that I have not tried yet?


***UPDATE....tried the common ground coil plug. Nothing. So I am officially out of options. I plan to purchase a external tachometer and try to get it to register an RPM signal. That will at least tell me if the problem is with my car or with the controller.

If you chose wisely the CAN bus thing can give you RPM.

A coil will be useless.

Here's an idea: https://www.msdperformance.com/produ...ies/parts/8509

Not sure which sensor that you're reading from on your car but this will generate a 12V square wave pulse each time the sensor triggers.

I have a black-box I have designed that converts various external signals into CAN bus and vice-versa. It's originally designed for cars that are lacking in OBD2 but I can tweak it for just about anything. I'm in Dallas and would be glad at looking at your application. PM if interested.

Can you expand on the lack of luck you've had with the CANBUS module? Which one is it, and how is it connected? I would've thought that way would be the easiest.

Yeah...I really wanted that to work out!! I even got the same one you sent me the link to! I know that I am getting the relevant data from the OBDII port because I am using a OBDII bluetooth adapter to feed the DashCommand app and I get tons of data from that. The signal is there!

PM sent. I really hope you can help me with this. What I need is a smooth analog signal for a controller. That is what the CANBUS interface was supposed to do. I dont think the MSD module can help with this application, but I am probably wrong.

well...ordered an external tachometer and hooked it up to the possible RPM signal sources (CANBUS interface, #1 cylinder coil-on plug common ground wire, and crank position sensor). I got nothing from any of the three. This leads me to believe that the XF uses a combination of sources going into the ECU to derive RPM and sends that signal to the in dash tachometer and the OBDII port. But I now know that the OBDII port will not yield an analog signal even with the CANBUS interface, leaving the only possible source to be the in dash tach wire....which makes this job a hell of a lot harder than initially planned. Hopefully, we can figure this out on Saturday.

I don;t even want to think of the nightmare I will have to go through when I start plug chopping!!!!

There's very unlikely to be an "in dash tach wire" - the instrument panel will display it based on the CANBUS RPM signal.

Some OBDII ports can block the CANBUS messages of a lot of internal signals like RPM. I'd be looking at tapping the canbus interface at a different connection, like the In Car Entertainment console. I'll see if I have the wiring diagram for it. There's some really good resources out there on this, I spent a while trying to make sense of it all at the DEF CON car hacking village this year

geez man....I about butchered all the wiring in this car trying to get a tach signal! I mean...has no one ever put an external tach. on an XF before???!!!

Surely I can't be the only person to look for an RPM signal !!!....lol...any help is greatly appreciated

How did you wire the CANBUS interface to the OBDII port? Which wires went to which pins? Just wanna check against the diagrams I have to make sure it's right...

As it's available anyway (except it seems to you via the things you've done), probably not. Everyone will just use the CAN/dash info I expect.

I don't understand how you can be having so much trouble.

There is probably no ANALOG signal for rpm. It's unwanted (except maybe by you). About the nearest might be what the ABS module sees.

yes. thanks for your input. however, the controller i am trying to use requires an analog signal that provides tach info. Just out of curiositity, in England, do people really only drive manual transmission vehicles? If so, then why the hell don't you send us some manual Jaguars...lol...then I wouldnt need to find the tach signal because I could go off of shift points!

Also, have you ever heard of company by the name of Tom Lenthall, LTD.?

ground to pin 4 (tried pin 5 also)
power to pin 16
Can Hi to pin 6
Can Lo to pin 14

Since the XF is running the CANBUS spec, the slots for ISO9141 and J1850 dont even have wires going into them.

I was thinking of getting the Auto Meter 9117 Tach Adapter. It looks like it may work, but I would need to find a common power wire to all of the coils. Just tired of splicing into all the wires ....lol