A question for the mad engine swappers

How do you make stuff like electronic instrument panels, electronically controlled transmissions, and speedometers (electronic or mechanical) work?

I'm thinking specifically of the LS1 & 4l60e into a BMW E34 touring swap job that Vasbmw is working on In this thread

I understand how to make the mechanical parts fit & the engine work, but how do you make all the other bits work together, so that when its completed its a fully functioning car that you can drive on the street?

I realize that the details will be different for every mixed brand swap, but I sure would like to know how to make the speed sensor in an american transmission drive a german speedometer in the electronic age. .

Chances are the speedo signal isn't far off - they're typically just pulses. You might have to alter the voltage a bit with a pull-up resistor. More importantly, you'll have to calibrate it. Dakota Digital makes a box that will do exactly that. They also make one that has a little motor inside that will spin a mechanical speedo cable at the appropriate speed to drive an old-school speedometer.

The transmission will likely be controlled by the same PCM that's running the engine, no worries there.

Newer cars (such as a 2009 Miata, to pick a random example) might have a CAN bus system. That can be a challenge. An E39 BMW might also be a bit tricky with the IBUS - but I don't know if that runs the instruments. E34 is probably old enough that you just have to feed it sensors in the right range. In many cases, that's a matter of mounting the car's sensors in the engine. We use an adapter on the LS engines that lets us mount the (small) Miata coolant temp sensor in the (big) hole in the LS block.

Take a look around Dakota Digital. They make all kinds of stuff that will accomplish most of it.

I read a lot. I occasionally ask questions. Then I try stuff. Sometimes it works. Sometimes I make smoke. Either way, I always learn something.

Bryce

Nashco wrote: I read a lot. I occasionally ask questions. Then I try stuff. Sometimes it works. Sometimes I make smoke. Either way, I always learn something. Bryce

This.

or put another way:

"Wisdom is gained from experience and experience is gained from a lack of wisdom"

On an E34, instruments are VDO and like all electric gauges, mostly just voltage meters that need the right sender to provide the range. The tach is a VDO tach so you just need a pulse like Kieth said.

Some of the newer stuff is more challenging for the home wrench where you have to interface analog data then serialize it to the CAN bus with the right address and data but it is just a different skillset, not really that much more difficult. There are tools to stream the "messages" out so you can trace what addresses go to what devices if you are working on something that hasn't already been reverse engineered.

To avoid this - I only swap new engines into old cars :)

Giant Purple Snorklewacker wrote: To avoid this - I only swap new engines into old cars :)

This has worked well for me so far.