onionpatchkid

This is probably just a general question about cars but this weekend I was driving and the red "!" light came one and started flashing. I noticed the volt meter indicator in the dash pod was bouncing from 10-12 volts. I changed the battery when I got home and that didn't fix the problem. Is this just an indication that the alternator isn't working properly? Or something else?

FredR

The voltage indication signal is taken from the alternator via the engine harness to the 14 pin connector in the engine bay and then via the central electrics to the display panel. If you have the original wires in that harness chances are they are completely shot. I have not checked the wiring diagram for your model year but I suspect the core in question is the one passing through terminal 1 of the plug.

onionpatchkid

I'm pretty sure the wires are original. Are new harnesses available or am I in trouble? Is this going to be an expensive repair to pay someone to do it?

jpitman2

I have had odd bounces on Volts and temp in my car, which were mostly fixed by cleaning the connectors onto the pod contacts. The blades in the connector hoods are easily bent if probed with a meter, and then need retensioning to improve contact/ Also cleaning (eraser on pod circuit, Deoxit on blades will help. I had temp increases when turning on lights.
jp 83 Euro S AT 57k

onionpatchkid

So you guys don't think it needs a new alternator? It's a wiring issue or connection issue at some point between the alternator and the pod?

Mrmerlin

You would do well to remove the voltage regulator and inspect the brushes. and the slip rings,
also give the alt a spin make sure its smooth and free.
Check/ clean the wire connections at the battery, the starter , and the alternator and 14 pin connector and the hot post stud ( 11mm) ,
make sure all are clean and tight

onionpatchkid

So in the picture above, there's a wire connector to the left of the air intake hose on the left. It's about 12" back from the radiator and has some red tape on the harness. Is this the area I should check and clean? The rubber cover on these wires does look browned.

The Forgotten On

That is the 14 pin harness connection and where you should do some cleaning.

The pins likely have some corrosion on them as the cover plate is missing. Undo the connector carefully and clean the pins with some deoxit and reassemble.

You will most likely need to replace that harness ( a few people on here make them) as most of the wires are probably shot as stated above.

jpitman2

Yes - there is a hex bolt sticking out - that has +12V on it ALL THE TIME! There is a 14 pin connector above the bolt that controls several things. Disconnect the battery, separate the plug from the socket, check that all the pins and sockets are clean and free of corrosion. There should be a plastic cover over this connector - I think 92861287102 - clips onto the edge of the fender - shields the connector from water running off the fender or hood. Also a cap is available for the hex bolt to prevent accidental shorts - dont know this number. Also check and clean all your grounds. Nice engine bay
jp 83 Euro S AT 57k

Petza914

Aside from all the other superb advice here, I'm assuming the needle wasn't jumping when the turn signal was on or if you were pressing on and releasing the brakes, or maybe the air conditioner compressor cycling. My needle jumps up and down with each flash of the turn signals, or when I press the brakes (drops when pressed, pops back up when released).

onionpatchkid

No. The red exclamation light blinks non-stop with no other actions. Even while just idling. It was weird. I drove 10 miles with no problems. Parked, came back 45 minutes later, fired it up, and it started blinking. Went to another place, parked, and when I started it again it didn't blink but I drove a few miles down the road and it started blinking again and blinks every time now. Pod voltage meter bounces with the blinking so I thought maybe the battery needed to be changed. I bought the car in August and it looks like the battery was from 2012. I do keep a trickle charger on the car quite a bit at home because I don't drive the car much. Could the trickle charger have damaged something? I will check the 12 pin junction box this weekend. I do see a bare wire coming out of the box which looks like at 1 time had insulation on it. Sounds like the problem is in that box. I have a mechanic testing the alternator tomorrow to make sure it's good. I'll post the info of what I find on this so everyone knows. Rennlist and you guys are an amazing resource. That's the best $18 I every spent. Probably saved me $500 when my headlights weren't working right and I was able to get advice and fix it myself.

Thanks guys!

Doug Onion

Petza914

By trickle charger, I'm assuming you mean a Battery Maintainer like Battery Tender or C-Tek brand that monitors the state of charge and automatically switches between low amperage charging mode and float / maintenance mode, and not an old-school trickle charger that constantly supplies amperage. Even if you were using the old style, I think it would only damage the battery itself, and not the rest of the charging system, but could be wrong about that and maybe it could damage the voltage regulator or some other component. I'm also not sure specifically about the 928 but most Bosch alternators on European cars have a trigger wire that needs to sense a certain voltage before they'll actually start charging. If the bare wire you mention is this trigger wire, your alternator may not ever be going to charging mode.

FredR

The thick brown cable is in fact supposed to be a red cable carrying power via the hot post to the central electrics- the degradation is typical- try flexing it and see if the insulation cracks and falls off- assuming it is there to start with. Take a look at the cables entering the 14 plug from the engine side [top section of the connector]. You may find bare cable- most probably you will see insulation of an indeterminate colour- most looking the same sorry mess. If so that may well explain your issue. That being said the other issues mentioned are also likely waiting for you given that if the engine harness is in such state then the rest of the potential issues will be no better.

onionpatchkid

I just got it back from the mechanic. Love those guys. I live in the Portland Oregon metro area and I can't find anyone that will work on the 928 but there's Canby Import Auto that is 7 blocks from my work and they specialize in European and Japanese cars but mainly Volkswagen and Audi. After I bought it I took it to them and asked them to completely go through the car and fix anything wrong with it. He had only worked on a 928 a few times (he's 30 or so) but he was willing to work on it. Did a fabulous job and he only charges $90/hour which I think is cheap.
Anyways, it was 2 different problems. Yes there was corrosion in the 12 pin box and that's why the voltage meter was surging. The alternator was working perfectly. The red warning "!" was because the car was almost out of brake fluid! I had no idea it was low. They found a loose fitting in the brake line. Total bill $100.00

Thanks guys for all your advice. I'm going to keep an eye on the wiring harness and 12 pin box and find something to shield it better from when I wash the car. I wash it all the time because it's black.

onionpatchkid

Here's a better picture of the cluster.