I have a 1994 E320 that's been through a lot. I swapped the engine in it about 4 weeks ago and after that it had what I thought was an antitheft or neutral switch issue and it would sometimes not crank in park and I would have to put it in neutral to start it. It ran fine like this for some time though.

Then I parked it in a bad spot and it "flooded" up to the door sills. (In my defense it had never flooded on my street before) The carpet did get soggy but after airing it out it worked fine aside from a clicking noise from the passenger foot well that eventually went away. Obviously not good but I figured that since it went away and still ran it must be something that controls the HVAC and I can deal with it later.

I then let it sit for about 2 weeks and now it does not have spark and it does not crank in park ever. It also does not always crank in neutral. Unhooking the battery to reset things sometimes lets it crank in neutral. The blower also comes on at random.

I'm guessing the electronics in the foot well are fried and some sort of anti theft system is stopping it from starting. That said it was having the intermittent cranking issue before it got wet. These may be two unrelated issues but I am hoping someone with more experience with these can point me in the right direction or what component is responsible for these systems. I'd like to make a junkyard run this weekend and grab whatever controller, relay, or switches that could be causing these issues.

Update:

Its not a ground, battery, or anti-theft system for sure. I've disabled the antitheft, changed the battery, cleaned the contacts, and checked the grounds.

I'm thinking that only leaves the ECU and neutral safety.

Update2:

Tested the OVP and checked the fuse. That is fine as well. I cleaned the contacts on the neutral switch and it now cranks consistently in park but still no spark.

I'm going to grab a ECU from the junkyard and give that a shot.

Update3:

I replaced the OPV, relay next to the computers under the hood, and the security/alarm module in the cabin with junkyard parts and the starting issues is solved. It still has climate control issues and I will be looking for a computer for that.

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Current fleet:
1995 C36
1989 190E 2.6 5 speed
1974 450SLC
1988 5.0 swapped Supra