danglerb

Yup, its a fuse tester.
Too dark to tell on wires, but typically solid brown mean ground.

6mil928

Congrats on the new baby.

Hilton excellent ground point reference.

Landseer

Get some more pictures and helping will be a little easier. I've got a stock 86 we can take some comparitive pictures of if needed.

They can be easier to sort out on the dining room table:

Landseer

Brown wire is possibly one that emerges from the fuse panel (CE panel) and is to be grounded to one of the firewall bolts above the fuse panel. You can figure that out by finding where bthe other end it is currently (no pun intended) connected.


Boot looks like part of the O2 sensor circuit, see picture below.

GlennD

Congrats on your new car. I also have a 86 with quite a few spares. I have a spare fuse panel fully populated so if you need pictures of the front or back, just drop me a line.

Glenn

eatiles

Great car, please post more pictures of the car. I got recently a 85 928S and I am doing all the work on my car, this is a great forum for any question. Good luck

utjmac

I'll try to get some more pictures later today. Yes, it sure looks like the O2 sensor circuit. Odd.

I was going to pull the whole panel, then remembered an old MB repair shop telling me horror stories of early 90 wiring harnesses whose insulation crumbled when you moved any of the wires. Cars coming in with simple repairs needed significant wiring replacements.

It's fine to just unplug all the harnesses from the bottom without too much risk?

Thanks all!

John

Landseer

Sure. Disconnect the negative from the battery first.

The insulation will be fine on those wires. Anyway, you really need to know the condition of the wires. If its brittle, you need to find it and fix it. More likely to find skinned wires (mice)or melted insulation back there. Spend some time poking around, you want to preempt problems especially in wiring.

Its the engine harness wires that can be bad, especially the part that leads across the front of the engine down to the alternator and oil sender. Also, in the valley, the crankcase postion sensor and various Bosch plugs for the TPS can be brittle and break up.

There is a sliding locking mechanism on the plugs that you need to scope-out so you don't break them.

O2 sensor has a heater inside it for earlier functionality during warm up. Do some searching, non-heater versions can be substituted. I'm not sure, but that may be the sensor heater wire and may not be needed if your O2 sensor was replaced. Search to be sure. I forget.

Congrats again on the new car.

Mike Frye

Confirmed: The O2 sensor is a 3 wire, the two in the black plug are heater wires and the green wire with the rubber boot is for the O2 sensor itself. (works to ground)

ddarnell

Congatulations

mcholdfast

Welcome neighbor. The satisfaction of fixing those issues yourself is just one of the many joys that your new toy will deliver. You're at the right place when you need help with the complicated stuff. You may want to start exercising those cheek muscles to be ready for the permagrin when you get it on the road full time.

ammonman

Congrats on the new ride. It looks very nice. I am a relatively new owner myself (March '09) and sorting out the issues is at least half the fun of ownership. +1 on what Mike said about the permagrin. Had her out last evening with my son and his buddy and all three of us had the permagrin going when we got home. If you don't already have Jim Morehouse's set of CD's with the WSM and all the other tech documentation I strongly recommend you get them. They have saved me much frustration.

Again, welcome to the shark tank.

MIke

linderpat

Congrats on your new acquisition. There are two projects that you need to do right away, and they cost next to nothing (I did them this past winter on my prior 86.5). First is a ce panel R&R, and second is the blower box R&R. The water getting on that panel, causing corrosion and sorts of electrical ailments, is coming from the blower box housing that sits right above the panel - where the fresh air comes in. It has a seal on it, and it is a 2 part affair - top comes out from the engine side - just behind the firewall on the passenger side in the wiper area, and the bottom drops out from the inside in the passenger footwell above the ce panel. There is a vacume actuator in there that's good to replace, and it is a good time to clean everything in there real well and get the blower really pumping.
As to the CE panel, all sorts of things may wake up after you pull and clean that. Try to get ahold of the wiring diagrams correct for your year to have for the job - clean up the stuff that should not be there. Some excellent starting point links are Sharkskin's write ups, especially on the ce panel r&r (even tho his car is an older version with the different style fuses, the same basics apply). Link: http://members.rennlist.com/sharkski...04-Bzzzzzt.htm. Here is a blower link: http://members.rennlist.com/sharkski...er-HoodPad.htm. Here's another blower link from Tony's page: http://members.rennlist.org/v1uhoh/air.htm. Also look at the DIY section of this board for more links and reference points, and search for more threads - tthere are a lot of sources here, and I read everything before I start a job, so that I am pretty familiar with what happens once I open her up!
Here are some pics of my work on these areas, and note how clean the panel is and how it should look, plus the wiring on the back side (don't pull any of those out!):

KLVA

Keep looking!!! I spent a year and a half looking for mine and ended up going all the way to Minneapolis for my 88 S4... I wanted the best condition body, paint and interior I could find and all the electrics and mechanicals allowed me to get to know the model and how to fix. Lots of time on the learning curve, as you might have guessed, pulling the trigger was easy after I had educated myself as much as possible. What are the things you like to do ?? Paint and body repair ?? Electricals ? Drivetrain and mechanicals ?? Find the one that has issues you will want to tackle...Mine was all mechanical: axles, oil pan, steering rack. brakes, intake, et al. The body was almost a 9 and the interior was a 9+++. Paint a strong 8.5+++ Price can always be negotiated for the right car Good Luck Irish !!

F451

Great advice.

Heinrich shared some advice a while ago and I really liked it. He said something along the lines of that there are three things to consider with any car purchase. Exterior, interior, mechanical. For 928's, he said if 2 or of three are not in good shape, consider passing on the car unless you are prepared for a substantial investment of time and money in order to bring the car up to snuff.

Seems simple when stated like that and I think its especially appropriate when considering a 928.