BMW conversion 1JZ - Fault Code 42

[Dispatcher]

Hello all, I recently converted my BMW E34 with a Manual 1JZ from a JZZ30.
The conversion was engine bay stuff only. The Dash / Instrument is all BMW.
I now keep getting FAULT CODE 42 Speed Sensor something ..
Can I just Ignore it ? or DO I need to fix this problem. IF so need some advise on how to please.

Thank you.
Dispatcher

[CrUZida]

You don't NEED it, but it may help with idle, and it may help with economy.

[Dispatcher]

Thanks Cruz, what do I need to fix it ? did I miss a socket to plug in ?
OR is it something more difficult to fix ? I want good fuel economy and idle.

Cheers
Dispatcher

[CrUZida]

The signal is from the dash to the ecu.

Its a 4pulse/rev output.
ie, pulses 4 times to earth per rotation of the speedo cable.
Even cars without speedo cables have it, but its electronically generated at the correct frequency.
It normally goes to things like cruise control, power steering ecu, auto ecu, etc.

You'd have to find out what the BMW uses for its speed inputs.

I can't really help any more than that.

[Dispatcher]

Thanks, I think you've given me the gist of the idea.
I can now track this down.

Appreciate the info.

Cheers
Dispatcher