If it was me I would go through the tests in the manual (link below) before ordering parts- looks like they are plug and play (not like a Transit one) but may be wrong. Compared to the cost of the chipper or even a Vanguard engine I don't expect the special tools shown in the repair manual are that dear. https://www.mudbuddy.com/manuals/vanguard/vanguard-37-efi-repair-manual.pdf