MyE28.com

Long time reader and user of search, first time asker, hopefully future contributor.

I have a collection of problems which seem to have the G103 ground in common. I am convinced that it is a wiring issue.I have searched online and on this site. Others who have had problems similar to mine, and have solved them mention this ground. I won't go into the problems "yet" because my story is long. Longer even than this.

Its an 88 528e 5/87 manufacture Motronic 1.1
I have the Bentley Manual
I have the pdf of the Electrical Troubleshooting Manual

I can't find the G103 in either of two places that have been suggested. a) Mounted to the intake just above the starter or b) under the diagnostic connector. I have followed the large bundle of wires that runs down the driver's side of the engine from the Motronic unit under the dash to the end of everything I can see.

From my searches apparently other owners have had the same problem finding it and no correct answer has been given. It was last mentioned on this site in 2007, the guy said he'd look later but didn't post back.

So I wonder... if he, or anyone else has successfully located the connector, or has information about it possibly being replaced with some other arrangement please let me know.

Thanks in advance everyone. I may post back with the problems I am having in case there are other suggestions but for now, I've convinced myself that I need to find this.

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...and in addition

This is theoretically where it is and what it's for:

G103, above starter motor on engine block
or intake manifold stud is ground for:

- Purge Valve
- Throttle Switch
- Main Relay
- Idle Speed Control Unit (533i ONLY)
- Idle Speed Control Unit (528e)
- Motronic Control Unit (7 ground wires)
- Flywheel Sensors cable shield
- Coolant Temperature Switch
- Coolant Temperature Sensor
- Filter Capacitor
- Oil Pressure Switch

Which one is under the steering column? Thats a major ground, but I dont know which one it is.

G200 is the one under the driver's side dashboard, in the vicinity north of the pedal bracket, towards the windshield. Rod Paine has a photo on his website of it IIRC.

G103 is an actual ground point, not a connector, BTW. Connections in the ETM are Cxxx while grounds are Gxxx. If you're expecting to find one or the other you could look right past it.

Other than the one under the steering column there is a ground point under the back seat and there should be one going to a stud on the intake manifold. I know the M20 has the ground connection to a stud on the underside of the intake manifold, but I've never had an M30 powered car so I dont know where to tell you to look in that case.

But it is an M20 ...

G103, acording to the ETM, should be located "above starter on engine block." I seem to recall that it is located on the intake manifold, towards the middle or front of the engine (possibly at the bracket for the diag connector.) Since it is a super-eta with M1.1, you should have a small bundle of grounds that go from the fusebox (C101) directly to G103. See if you can follow those.

Found a picture of my intake removed.

This is from an "i" intake (disregard the injector harness and bracket), but I believe the locations are the same. It should be either the stud on the far left along the seam, or the stud at the bottom of the #5 intake runner.

Dan is right. There is no "connector" per se. Just a ring that goes over the stud.

Your best bet will be to remove the airbox to get a good view under there. Easy job, 5-10 min max

Thats a very good picture of the stud it should be bolted to. Right on #5.

I wanted to post the final outcome...

Thank you all for the input.

OK, I never found the G103 on my car. There were two possible locations. It did not seem to be in either location.

(Here come some photos I took)





I have to deal with the very real possibility that my car has been... err... post production engineered.

Anyway... the problem I had... notice i said "had"... was a very bad stumbling problem after it warmed up. When cool it ran, ok, but not great. Sometimes it did run good. Good enough that I wanted to keep it. It was really frustrating. The temp needle would swing wildly, sometimes the "economy" meter too, then it would clear up and be ok. Horrible.

I replaced several things. Fortunately, things that needed it, mostly.

Man, I checked, tightened, replaced, wiggled etc. But I spent most of my time on the drivers side. The intake side.

Somebody, somewhere mentioned a ground on the passenger side, blah, blah, blah, but it was late and I was already settled in for the evening. I figured I'd check it later.

It referred to the ground on the passenger side motor mount.

Well, very much later, in desperation, I went looking for it. It was loose as hell. Big ground strap. Even as I was working on it, I did not expect it to do anything. There were other grounds to the engine. I pulled it off. Cleaned both ends. Tightened it down.



Holy moly. It runs better than ever. One ground. One. Dammit!

It's so smooth, and quiet. The temp needle goes where it should... and stays! It gets great mileage. Doesn't use oil. The air conditioning started working(bad ground to the compressor, I guess)! Pretty fine for a 22 year old car.

Thanks again to everyone. I'm still reading, but everyone here is so sharp that I haven't been able to help fix anyone's problem, but I sure am learning a lot! I've been working on cars for years, but I am still new to BMWs.

Mike

emteemac wrote:Snip... Holy moly. It runs better than ever. One ground. One. Dammit!

It's so smooth, and quiet. The temp needle goes where it should... and stays! It gets great mileage. Doesn't use oil. The air conditioning started working(bad ground to the compressor, I guess)! Pretty fine for a 22 year old car.
Thanks again to everyone.
Mike

Mike,
Well, that's one I've never seen, so glad you found it and posted a photo. On the 4 or 5 1988 528e models I've worked on, the grounds have been in different places and I have had to track them down, too. My friend waynet has an '88 and will be stopping by on his trip home from RI to FL. I'll take a look at his and take a few shots and post them on my web site to help others in the future. Keep your grounds, fuses and relay tab contacts clean and you'll have a very reliable 528e, as most of us have learned.
-Rod

jmc1590 wrote:But it is an M20 ...

G103, acording to the ETM, should be located "above starter on engine block." I seem to recall that it is located on the intake manifold, towards the middle or front of the engine (possibly at the bracket for the diag connector.) Since it is a super-eta with M1.1, you should have a small bundle of grounds that go from the fusebox (C101) directly to G103. See if you can follow those.

So I upgraded my 535 with the harness out of my wrecked '88 Super ETA 528e moto 1.3. And now I've experienced varying running conditions and different symptoms depending on the ECU I've tried (bucking, idle issues)

I have searched for a bundle of wires as described - but cannot locate anywhere. All I have are 2 wires wrapped together running to the battery - should one of these connect to the intake ground stud? They originate in the same place/bundle as C101... But that's all from the harness to the battery on ground side - does the battery only hook up to chassis ground?

In this pic - center connection - "Battery Neg (-) or G103"


Possibly? maybe? thoughts?

Bump for anyone who knows more info about grounds?

dhcg86 wrote:Bump for anyone who knows more info about grounds?

you already have a thread for a ground issue, why resurrect an old one? Search for the ETK, get a Bentley, and study...