Hello Guest, welcome to the initial stages of our new platform!
You can find some additional information about where we are in the process of migrating the board and setting up our new software here
Thank you for being a part of our community!
I know the Volvo Wiring Diagrams site is kaput..... but can you find the 89 harness schematic somewhere? With luck, you might not have to customize too much to get power to the LH2.4 harness. Having gutted a 94 9 series once, you will likely need to pull it all the way to the ECUs to get proper LH2.4 function.
Option 1 - build a MS2 harness, use Tuner Studio and with some help on base tuning, you could have less hours (and more fun/learning/tuning gains). Data logs, lots of +++ features of Megasquirt that LH2.4 can only dream about.
Good luck.
When I converted my 89 740 to LH 2.4 I used a 240 lh 2.4 harness. It is basically a stand alone harness. No ripping the dash apart to change everything..
I know the Volvo Wiring Diagrams site is kaput.....