cek wrote: Apr 02, 2021 10:54 PM
I have BR/GN tied together on pin 85 of both relays (i made a mistake when extending the harness).
On Saturday, after sleeping on the above statement, I dove into the various ETMs (and the two extra M1.3 harnesses I have). I turns out 1990 and before M1.3 systems had the O2 Sensor Heater (triggered by PIN 23 BR/GN on ECU), but after that, BMW realized that was stupid and just fed the O2 Sensor Heater off the Fuel Pump Relay (triggered by PIN 3, also BR/GN on ECU).
1990 E34 ETM:
1993 E34 ETM:
For refreshers: Motronic 1.3 ECU plug:
I discovered that PIN 23 of the two E34 M1.3 harnesses I have DO NOT HAVE wires connected.
Thus, a new pro-tip: A 1990 and before M1.3 harness will have a visible plug connector at PIN 23. A post-1990 Motronic 1.3 harness will NOT have a connector at PIN 23, but it will STILL have two BR/GN wires, both coming out of PIN 3.
Adding to the confusion is the fact that the Oil Pressure Sender has a BR/GN wire (to cluster via PIN 14 of the C101)!
DO NOT BLINDLY JUST THINK BR/GN is unique to fuel pump/O2 sensor heater when adapting an M1.3 harness to the E28.
Recall the issues I was seeing:
1) Fuel pump always ran (when ignition was in ON).
2) Fuel pump relay buzzed.
3) Pulling the main relay would NOT stop the car.
As i was messing around with the wiring harness, with the main relay pulled, THE ENGINE (and buzzing) STOPPED. I took a video of this:
https://www.flickr.com/photos/ckindel/5 ... ed-public/
Uh, this means that I had a failure inside my harness. I was already considering that I'd have to pull the harness and redo the fact I'd screwed up the O2 Sensor Heater Relay wiring (and remove the relay all together). Now I knew it was coming out.
So I pulled back the insulation (F4 Tape, which, by the way I remain a massive fan of; it is by far the best thing I've found to wrap wires in a hostile environment like an engine bay).
Ugh. Another lesson learned (which I already knew, but ignored when I built this harness): when adding splices to a harness, do not let the splices be lined up with each other, OR ensure the splice points can't wear against each other. Also, apparently, the heat shrink tubing I used was of poor quality:
Like many things in this life, I'm extremely grateful that THE WORSE THING THAT HAPPENED with all this was my main relay was stuck on. I could have been stranded in Utah without the tools to fix this!
I then set about removing the harness from the car. The hardest part of this was getting to the wires on the starter.
I got to use my glow in the dark 10mm sockets (Thank you @karlgrau!):
This is embarrassing; I never really dressed all of this. Now, I'll do it right. Note blob of F4 tape on left? That's the Seattle Circuits econometer adjustment circuit that ensures my fuel economy reads correctly with bigger injectors.
Free!
Inspecting everything on the bench, revealed this (oil pressure sender):
So, I would have needed to pull this harness (or do a hack fix) sometime soon anyway (always make lemonade!).
I had used E28-style relay holders when I did this originally, instead of the M1.3 style that were on the donor harness. Don't recall why. In looking at this harness and my two spare M1.3 harnesses (one Super Eta and one E34) I realized the wiring was more robust. Since I needed to re-splice and I needed new lengths (to ensure the splices were offset from each other), I hacked the E34 harness (sorry!) and used those relay holders.
A bi-product of doing this (which is probably why I didn't do it originally) is that GR/YL wire on the E28 holder is fed by the OBC Immobilizer. By using the late-style main relay holder, and wiring the immobilizer will no longer immobilize. Which is probably a good thing.
I spent most of Saturday afternoon and all day Sunday carefully cleaning, inspecting, re-splicing, testing, and then re-wrapping the harness. I removed a bunch of extraneous wires that are not needed for a swap (weight loss!) as well.
The F4 tape I prefer does not have a blue indicator stripe on it. The stripe is there to ensure you overlap 50%. But once you use the stuff you don't need that and the blue stripe is often visible and looks ug. So I prefer this stuff:
https://www.amazon.com/X-Treme-Tape-TPE ... =ceklog-20
I got her back together with little drama (the damn wires to the starter were the hardest part, again). I found one of the ground wires to the hood hinge was failing, so I re-did all that along the way. Note I didn't clean around the fuse box, because a "Galahad E28 Fuse Box Blade Style Kit Prototype V3" should be here today and I'll clean there once the fuse box is loose.
He stared right up with no issues related to the harness (*).
Then took a long drive to a nice Easter dinner with my daughter, her FIANCE (!!!), and his family.
What a car.
