Another way to tell if your wiring harness has turned crispy. This is on a 92 400E with 133Kmi and no evidence of replacing the harness (VMI or the records from the last few years)

I was concerned that the harness may be the cause of problems since I was getting the ASR going into limp home mode, also the ground wire that comes off the harness under that air cleaner looked cracked. I pulled all the codes and figured I'd see what showed up when I start to drive it. (I'll post codes later when the car is on the road if anything reappears with the harness replaced)

But, on going through some other items in the car I figured I'd see if the insulation was craking on some of the wiring. Lets check one of the temp sensors twards the front of the engine (figured I'd slit the overwrap to see the individual wires). Give a light tug on the body of the connector and it split in two! Pressed on the release tabs on the sides of the connector and they both snapped off!!!!

So looks like I need to replace tha harness. Hopefully that will cure the flakey codes.

Now I'll fix that as well as small rust spots on the doors. I should have it on the road in a couple weeks

Paul