W124: Is this the onset of Wiring Harness Failure

[rngadng]

Friends:
I fear that this might be the onset of the W124 Wiring Harness Failure. Please advise if you think it might be something else (i.e. less expensive!):
--1995 E420 (W124, 8cyl, 117,000 miles). No damage history.
--Check engine light keeps coming on (I clear it, then 5-10 starts later, it comes on again)
--Error Code 26, which I understand to be the Electronic Control Module (also called the Elec Control Unit), the "brain" of the engine.
--However, if it is the brain, I am NOT experiencing any performance problems of note!
--But for the check engine light, I would not have cause to think that I have a problem.
--If it is the wiring harness, I understand the part number requires careful attention. Any guidance there is also appreciated.
Thoughts?
Thanks in advance.
RNGADNG