8L you have to worry about. number one cause of 8L is wire broken at brake unit, where it twists. K2 replay pins burned....thats the key on positive power supply. Last is the pin at the VM. Thats the brake negative output power. It will smoke. JPC20-14 terminals burn. You dont have to replace the harness and VM. Open VM and add jumper wire to JPC20-14 and route to harness. Lots of power in this ckt. K2 relay takes a lot of heat.
PUT new relays if you didnt already. That relay card will cause all kinds of problems. It has to be 100%!!!! As long as you have corroded or burned terminals, nothing will work.Code 61 can be caused by a bad or mis-adjusted prop valve
I have brand new trucks from the factory giving codes from bad connections at the VM. So any moisture or corrosion will make things code out.
G-day!