kuwona

Hi Crew -

My voltage gage was starting to get a bit flickery a while back. While driving it would sometimes start vibrating within the 11-12 volt range but would then go back to a normal steady position at around 13. I figured it was probably gage related.

Then yesterday my radio was cutting out and coming back. I looked down at the dash to see the needle at about the 10.5 position. My alternator warning light works, but has not come on.

Voltage at the terminals and at the jump post is 11.85 with the car off (using a Fluke multi-meter), but goes down to 11.45 when the car is running.

I guess I should clean some connectors, and looking at the previous posts it sounds like there is a good list of connections to clean from Wally, but I haven't found that list.

How do I get at the 12-pin connector I keep reading about? Does that connect to the actual alternator? Do I need special tools to get at the alternator? Is it a half-hour or half a day? Who's got an alternator for sale?

Thanks,
GW

rixter

14 pin connector is located adjacent to the jump post
BE CAREFUL when removing the top to avoid the problem in pic# 2

the flyin' scotsman

There was a recent thread re. charging which I responded to and to satisfy the exact readings on my car I peformed voltage tests the next day.

At the jumper post (under the hood, passenger side, blue cover) the voltage recorded was 12.9v with the engine off and 13.8v with the engine running. YMMV.

Given your results I would suspect your alternator is fried and requires replacement. You could try the main grounds for corrosion but the fact your readings decrease with the engine running signifies zero output from the alternator.

Garth S

Reading 11.85v is a good indicator of a discharged battery or one with a dying cell: confirm this by measuring directly on (cleaned) battery terminals. If this confirms the jump post reading, stick your charger on the battery to bring it back to a min. of 12.3v. If this does not occur, it is highly possible that the battery is dragging down an otherwise good alternator( via an internal short). A CCA load test on the battery will confirm its state of health - a freeby by most parts stores..
The alternator should output the 13.8 - 14v noted - but needs to dance with a good battery.

John Struthers

GW,
Keep eyeballing the Rog post.
Rixter,
Your pics reminded me of a bad day under the dash -pass side- the wrong part of the lamp control unit came off and the wires fanned out like convicts after a prison break.
The horror... the horror...

kuwona

Okay gang. The plot is thickening - or maybe thinning - Or maybe there is no plot... I've read the alternator threads from Rog and from Ozz. I've had the battery down to Autozone where it was charged and tested and passed. (I put it in a minivan and drove with it all week - it's definitely good). I took the alternator down to Boston Auto Electric where they were impressed with its performance and checked the brushes, and other innards and gave it two thumbs up. I checked the 14 pin connector (visually) and it looks good. Tonight I did the volt-meter check again with the battery freshly swaped back from a week in the minivan...

off = 12.8
idle = 12.4
increasing revs decreases voltage

I punched myself in the face 4 times. It didn't help.

I did notice this time that my gage lights (including the alternator light) come on only for a moment when I turn the ignition on and before I start the engine.

Any idea what that might mean?

In a post from Wally, I found a great list of places to check...

The power to excite the alternator has an elaborate route on your '82. You may need to check and make sure that the excitation current is getting to the alternator.
1) Battery to ignition switch.
2) Ignition switch to bus 15 (general switched power bus).
3) Bus 15 to terminal H7 on the central power panel. (Connectors are A-Z, left to right on the bottom of the panel).
4) H7 on a black wire to terminal 3R on the instrument pod.
5) Terminal 3R to the Generator light, and to a resistor mounted in parallel to the light. If the light is burned out, the alternator won't receive enough power to generate. Bad connection or bulb in the pod is a likely problem if the light never comes on.
6) From the light/resistor to terminal 11R in the pod.
7) Terminal 11R on a blue wire to terminal H8 on the central power panel. There are three blue wires here - power goes to the central warning computer, and to the mileage counter under the cover on the passenger door sill.
8)Terminal H8 to terminal Z6.
9) Terminal Z6 outside on a black wire to terminal Z1.
10) Terminal Z10 inside to terminal O8.
11) Terminal O8 on a blue wire to the alternator.

Am I looking for 12 volts at each of these spots with the engine running? Is the power panel what I usually call the fuse box? How do I identify a bus or a terminal? If I start with step 11, and it's good, can I skip the other steps? I guess I'm hoping to do the easiest stuff first incase I can avoid pulling the pod etc.

WallyP

One possibility is that the electrical portion of the ignition switch is not making good contact. There are numerous contacts in the switch, and wear can cause some odd problems.

The charge warning light should come on when you turn the ignition on, and should stay on until you crank the engine.

If you check for 12 vdc at the alternator excitation terminal (small blue wire) while the ignition switch is on, you can skip the other checks along the circuit - with the warning that it is possible for a bad connection to let 12 vdc pass, but not enough power (amperage) to actually energize the field. Visualize one of the wires in the circuit being broke except for one strand - you would get 12 vdc on a meter, but not enogh power to excite the alternator.

A bus is just a circuit - for example, the 30 bus is just unfused battery power, the 31 bus is just a ground circuit, etc.

The Central Electric Panel is where the fuses and harness connections live.

porsche928freak

Well , Thanks to wally for keep answering my questions, but now that i think , i am trying to fix my alternator light, but since i got the 928 any of the lights are turning on when the ignition is on, example: fuel gauge, oil, battery, so i wonder if still is the same problem or is it related to another problem?

Garth S

Please clarify: are you meaning that when you turn the ignition switch from 'off' to position #1 ( run) that the dash does not light up?
When turning to position #1, all the dash red lights should come on - never counted, but there must be 12-16. When the key is turned to start, all but the 'brake' light will go out - including the alternator light. If this is not happening, you are correct in thinking that there is an additional problem.

porsche928freak

in position 1 i don't see any lights on except for the stop light, i really don't know what can be the problem, the only thing is that i remember one day driving and suddenly all the lights on the panel went on, brakes, brake pads, battery, oil , all of them, i really don''t know what's going on
thanks again

Garth S

This is sounding more like kuwonas problem .... and if the dash does not light up like a red Xmas tree at position #1, it is likely the removable back half of your ignition switch is cooked! see the above analysis and then possibilities in post #7 as well.
There are two small bolts to release the electrical switch - and the Big 3 ( now maybe 5 ) can supply one for ~ $30.
This may not be all of your problem - but the dash must light up, and stay lit until the key is turned to engage the starter. This would be a good start ( no pun intended) .

porsche928freak

I'll check that right now, and can also be the central warning brain fried?, thanks!!!

ozz

porsche928freak

i just checked my 14 pin connector and it looks terrible , 3 or 4 cables and completely corroded and 1 i think is loose, so i will replace those wires, and i will also check the ignition switch, i'm still thinking if can also be the warning light brain

RDS928S

Here's another charging dilema:

my 86S charges fine (well above 12 volts) during normal driving with no accessories on ecept radio.
As soon as the front fan and or rear fan (AC) are switched on setting 3 or higher the voltage drops below 12 volts. Add the headlights and it drops further even when the engine is reving above 2000 rpm.
Also when the turn signal is used the volt gauge bounces up and down in sync with the turn signal.

Rich

WallyP

Don't depend upon the dash voltage gauge for accurate readings - there are about a dozen connections between the gauge and the battery. The sum of the corrosion and looseness in these connections is usually the cause for low gauge readings.

Always - the first thing to do is to check the voltage readings at the battery and the jump start terminal with a good voltmeter.