anchovi

Hi, super noobie here.

My uncle recently bought a 1988 Porsche 928 S4.
It wasn't in the best conditions...definitely a good find though!

He has a couple years of experience in automotive mechanical work but lacks knowledge in uncommon cars.
I've helped him out a bit in replacing a couple parts here and there for this particular car which brings me to the ABS light.

The ABS light is on. My uncle suspects that it has to do with the disconnected wires under the hood.

Below is a a picture i took of the car's under-hood sytem. Labels "A" - "K" are disconnected wires which my uncle believes are part of the vehicle's ABS system. Except for labels "F" and "G".

The following labels are indentical on both sides (LEFT & RIGHT) of the under-hood sytem:
Labels "A" & "K" are a group of 5 wires. Labels "B" & "H" are dual wires wrapped in black plastic. Labels "C" & "I" are also dual wires wrapped in black plastic. Labels "E" & "J" seem to be ground wires.

(Ps. I know very little about automotive technology in general so i ask you guys to please bare with me.)



* Label "A" (closer look below): a group of 5 disconnected wires.



We think that two wires from label "A" are supposed to be connected to label "B" using some kind of connector bridge.
That leaves three wires left. Two of them possibly go connected to label "C."

Label "B" : Two disconnected wires wrapped in black plastic.
Label "C" : Also two disconnected wires wrapped in black plastic.



The last wire from label/group "A" possibly needs to be connected to label "E"

Label "E" (Below): Very certain that this wire is ground.
Label "D": Unknown Male Connector. (Please Help Identify)

* of course...this is a just basic idea. We don't know exactly what wires correspond to each other since they don't seem to be color cordinated
nor do we know if that would even be a solution. (What are your thoughts?)



Label "F" (Below): Unknown Female (?) Connector. (Please Help Identify)



Label "G" (Below): Unknown Wires.

My uncle says the two wires from Label "G" may be for some sensor that's missing since they lead back to the harness. (What are your thoughts?)




Labels "H, I, J & K" (Below): Identical Wires to the ones on the left side.

The basic solution i proposed for the left side, if correct, would apply to the following right-sided wires: (What are your thoughts?)




Input from anyone on this forum that has a bit of knowledge on this subject would be greatly appreciated!!

- Anchovi

outbackgeorgia

WoW, that's all I can say. You have big job on your hands. First, you have no air filter, so if this car is running, I would get an air filter first before the engine is damaged. Second, it does appear that some of the wires are for the ABS, but from your photos, that is the least of the issues with this car. You need a wiring diagram to sort out the wiring. The wires are color coded, but the connectors may have disintegrated (turned to white dust!) as did mine (87S4).
Where are you located, there are many on this forum who can help, but it is better to know your location, possibly some on-site help?
If the tape on th temp sensor wiring is an indication of wire spincing skills available, you may have a long road ahead.

Others will chime in on the forum. Have you read the FAQ's at the top of the forum? Please read first!

Dave

longleader

http://www.ligeti.com/928/
This may help

Hilton

Looks like someone used the harness as a donor for all the connectors to use on some other project.

Wow.. just wow.

Is there a MAF sensor (under the airboxand is it connected? (has a 7-pin Bosch connector on it)

I see you've connected up the Temp II sensor (the connection with electrical tape covering the wires), so the car presumably starts and idles/drives?

For the ABS - wires labelled A, C, I and J in your pictures are likely them - there should be a barrel connector which those plug into bolted to the aft side of each shock tower in the engine bay (the brown one on each side is ground and goes under the bolt head.

Its very likely some of those wires are the ones that should plug into connectors T15 and T14 at those points (in quadrant O-75). You can tell by the wire colors (e.g. should be two red wires on front-left side to the ABS sensor in the wheel well). See the attached bit of the 88 wiring diagram below.

You should probably also check the harnesses in the rear spare tire well (just by the battery box) as those are where the rear ABS harnesses connect.

These pages are probably useful: (labels for each numbered item are in the drop-downs)

http://members.rennlist.com/v1uhoh/underthe.htm

http://members.rennlist.com/v1uhoh/underww.htm

Get yourself PDF copies of the wiring diagrams (can be found via bittorrent, bought from 928 vendors, or on various web sites).. then you need to start cleaning and checking wire insulation colours/stripes.

Depending how much your uncle paid (or was paid?) to get the car.. it looks like your best (cheapest) bet is likely to just sell it and get another that is in much better shape.

Lizard928

Well, you are going to have fun with this one!

Label B (and as noted later H), are likely ABS sensor wires.
With label A being brake pad sensor wires, as well as sensor to the coolant reservoir, and other sensors in that area.

Label D is for the hood pin switch. Not required though good to have for the alarm. The switch would bolt to the piece with the long slotted hole to the right of the connector.
Label E does not look like it is a factory wire, nor should there be one there like that.
Label C Is likely for the overheating switch. This is a commonly deleted part (Thanks Porken!)

Label F is the Hall effect sensor, without it connected you will be -6 deg of ign retard at pretty much all points in the rev range.

Label G is the lead that SHOULD connect to Label F. You will need possibly lengthen this lead as it should run down the front of the engine then under the passenger belt cover coming up and connecting on to the Hall effect sensor.


Label J is a ground, bolt it to pretty much any good bolt until you can locate its proper grounding point.
Label H does appear to be a double shielded wire, this could be an ABS sensor.
Label K is likely for the brake pad warning,
Label I is likely to be the brake fluid reservoir sensor.

Your best bet on all of these is going to be to get the wiring diagrams on PDF (contact ROG100 or roger@928srus.com for this). Then to also have another 928 of the same year side by side to look at to see how things are supposed to be. I was just troubleshooting an ABS system today and found a seized ABS pump motor. You will be needing to fix B & H for ABS, and then your fun is going to begin!

Also K&A likely go to the brake pad sensors. Please jack up the front end and remove the front tires. You will then need to take a few pictures from behind the wheel looking forward to confirm what is there/missing.

Sorry if this post jumps around a little, I was having to go up and down to see things.

Lizard928

Also, please note where you and the car are located.
There is likely another member in the area that you may be able to have his car parked beside yours while you look at where his wires go.

Stromius

F is your Hall Sensor connector.

Leon Speed

As others have said: wow. Can't imagine what people think who do that.

Hopefully these pics help to figure this puzzle out.

Note on the passenger side the following connections:




- ABS and brake pad wear sensor. These come together in the round housing (hey look, Dirt!!, need to clean those). Two wires per connector. The insulation is solid and round. There's a third connector plugging into the round housing, also two wires (I think brown/black), the insulation is a looser sheathing. A think bunch of wires comes out of the other end of the housing. Ground wire (thick brown), also coming out of the other end of the housing and is bolted to the bracket under the round housing.
- coolant over pressure sensor, above the round ABS/brake pad housing, two wires, looks like green and brown.




- hood switch, two wires, brown and green/brown.


Front of the engine:




- hall sensor (your F and G)

Drivers side:


- same ABS/brake pad wear sensor wiring
- low brake fluid sensor, two wires, looks like blue and brown

Hilton

Its worth noting that Aryan's barrel connectors have three plugs in them because his car is equipped with tire pressure sensors (RDK).

88 didn't have that, so the third plug on those connectors is just empty. (and US 89 models didn't have it as standard either - only RoW got it as standard in 89).

anchovi

Thanks for the input guys!

Well, we've got an air filter on the car now. The reason there was tape on the temp sensor was just to test it out.. they are professionally spinced now

I'm going to take new pictures of the under-hood components soon to show you guys the new changes and additions very soon.

HILTON..."Looks like someone used the harness as a donor for all the connectors to use on some other project." What makes you say that?
It does not have an MAF sensor. I checked out the links you posted but none of them actually have a label for the components i'm looking for.

My location is Downey, California. Is there anyone on here that wouldn't mind letting me check out your 87' Porsche 928 S4 in person? I'd like to compare my car to yours side by side to get a greater idea as to what the components should look like under the hood.

I'm willing to drive 15-30 miles from my area guys, please let me know!

Mrmerlin

First welcome to 928 Forum.
Lots of good info here.
If you can ask questions while providing as much detail as possible it will result in more correct information being provided,
thanks for posting pictures of what your working on as it makes a proper diagnosis possible.

That said,
Hilton is spot on, the results of your pictures show that the car harness was cannibalized for another car.

NOTE if you dont have a Mass airflow sensor then the car wont run, so you should have a MAF
its the big round silver barrel about 8 inches tall and 7 inches round thats under the air cleaner and should have screens on either side of it.

That said when you have some time ,
make sure to check out the FAQ thread at the top of the page ,
its long but very informative and most of the issues you will be tackling are addressed and answers are provided,
goodluck with your project,

Keep Em Flying!

S4ordie

You came to the right place for help. Some of us possess extraordinary skills, knowledge and experience, relative to these wonderful and obscure cars. I am not one of them. All I got is... you are missing a passenger side fender bolt.

You're welcome and it gets easier from here on out.

Bill Ball

Egad! You've gotten brilliant responses already. I'm 100% with Colin's suggestion that having another similar model year (anything 87-89 or perhaps 90) car to examine and compare would make the repairs much easier to understand. There are many 928 owners in the LA basin who hang out here and should be able to help. You may have to come up with some alternative connectors, but seeing how it is supposed to be in the flesh would help.

anchovi

Merlin can you please elaborate? You agree with Hilton about the harness being cannibalized for another car. But in this case, what does that mean exactly?

Please excuse my ignorance

Hilton

I meant it appears someone cut all the connectors off the electrical harness to use on a different car, or for some other purpose.

I can't see any other reason that someone would have just cut them all off