While the monochromatic wiring can be daunting for mechanics that are accustomed to colour coded wiring assuming the numbered tags are still intact and the wiring harness was installed as per the schematic doing any electrical diagnosis should be no more difficult than doing so with colour coded wiring. Suspect some mechanics may use monochromatic wiring as an excuse to make things more difficult (charge more) than need be. I used to wire electrical panels for use in the machine tool industry and we only used different coloured wires to identify different voltages and whether they were AC or DC circuits. Will admit that if PO have changed the wiring, you don’t have a copy of the schematic and the idiosyncratic combining of two or more loads on the same fused circuit it can be a real rats nest to figure out a problem. One of the reasons why when I replaced the dash and gauges i cut out the original harness and made my own
David B Dixon
Port Perry ON CA
Sabine