Codes 279D, 279B, 27b8, Wiring harness? Please Help

Hello all,
I am trying to help my friend with this car he bought recently, 02 E65. Check engine light has returned. First time had smae codes, We started by replacing the thermostat and the cleard the codes and after about a week the CEL came back, same codes

279D - Output stage, Electric fan
279B - Thermostat Jammed, (coolant below regulating temp)
27B8 - Differential Pressure sensor intake manifold, Plausability

So we have done t-stat already with genuine parts, and I found a bullitin online about replacing the engine wiring harness if the same code comes back.

Has anyone replaced the wiring harness to resolve this issue?

BTW, Fan is getting power, Signal- not sure O-scope crapped out...

Hoping that someone else has seen/repaired this before, Really don't want to tell him to go buy a harness if it's not needed.

Thanks for your time and help.

I would try using an ohmmeter before you start replacing harnesses. Those things are expensive and this isn't the kind of car you can just throw parts at in hopes of fixing it. I can't imagine a wiring harness would go bad that often.

I haven't experienced any of that but good luck.

Originally Posted by wilson009

I would try using an ohmmeter before you start replacing harnesses. Those things are expensive and this isn't the kind of car you can just throw parts at in hopes of fixing it. I can't imagine a wiring harness would go bad that often.

I haven't experienced any of that but good luck.

Check your alternator first, make sure you have a good alternator, had horrible experience spent money replaced parts according to the CEL error codes on my 745 and 325 but ended up all due to weak/faulty alternator, or alternator voltage regulator. Good luck.