wiring harness rot 95 e300d

[jhunt253]

i opened the wiring harness trey in the engine compartment today and found that the insulation on the wiring was cracked and separated on every wire in there. it amazing to me that anything works on the car.

does this "rot" go behind the firewall or is it safe to assume that splicing at the firewall would be an ok fix? also is there wiring diagrams available for this car?

thanks, hunt