Lorenfb

Remember, the alternator needs the alt. light to provide a starting current for its field winding.
Without that, the alt. will never begin to charge.

CRG

If you ground (there is a chassis ground between the ignition coils) pin 11 (the D+ blue wire from the alternator) with the ignition on and engine off does the battery light in the clock stay off or turn on?

Jason, thanks for taking the Tech Guru jab the right way
I did what you suggested and still no batt light in the clock?
Are you saying the D+ blue wire goes from the alt to the ignition switch at pin 11?

Lorenfb-

Remember, the alternator needs the alt. light to provide a starting current for its field winding.
Without that, the alt. will never begin to charge.

The blue wire supplies some minimal power to the alt to get it going, got it.
My disconnect is between the blue wire and the clock, I guess I just have to figure out how the blue wire gets to the clock?

BTW- I have the Porsche wiring diagram and the 1989 Mitchell Electrical Service & Repair Manual, so I have a small library... I just dont know what the hell I'm lookin at with this wiring stuff, It's like I'm reading hieroglyphics..

JasonAndreas

If the alternator warning light had come on when you grounded pin #11 (on the chassis side) of the 14-pin connector in the engine compartment fuse box then your problem would be located between that connector and the alternator (the original start of your problems). The light didn't come on so the problem is downstream towards the clock.
You mentioned that none of the lights in the clock illuminate with the ignition turned to start? There could be a short between Terminal 15 of the ignition switch and the clock (pin #15?) Or a problem with the clock itself (is that what Loren is hinting?). Do the lights in the other gauges illuminate? What model year do you have?

Indycam

What would happen if the wires were on wrong on the back of the alt ?

CRG

Indycam- you cant reverse the wires on the back of the alternator, three different size wires, three different size posts, three differnet size nuts

Jason- 1989 C4, lights work on other gauges just not clock

Tell me if I'm wrong but the D+ blue wire supplies some minimal current when the ignition is turned on (engine off) just as the B+ does direct from the battery, right?

So, if I turn the ignition on and put a meter on the D+ wire from the car I should get a reading? No matter what is going on with the alternator there should still be current supplied from the car (B+ and D+) to the alternator.

I need help in tracing the blue wires routing from the power source (battery) to where it supplies power (alternator). Backtracking it looks like it goes from the alternator to the ignition switch....??.. to the central informer..??.to the clock.??..to the battery? The problem cant be between the battery and the clock because the clock is keeping time, so it's getting power.

This is driving me to which by the way is a short drive

Indycam

"you cant reverse the wires on the back of the alternator,"
You can switch the two smaller ones . Bad design . The size of the post and or nut is dif , but the wires go on .
Have you checked the wires ?
Have you had it back out and looked ?

CRG

Indycam- I think it would be pretty hard to get the wires crossed, the B+ (pos, red) and D+(blue) are side by side and the ground (brown) is on the opposite side of the housing..I guess it could be done but I got that part right

Interesting enough, I have relooked at the Mitchell Electric manual for the car and it looks like the blue wire D+ does not bring power to the alternator, the pos (current) goes from the battery to the starter then to the alternator.

I'm taking the alternator off tomorrow and having it rechecked by another source, as it may very well be the VR.....if so, the thing was not rebuilt properly

What a pain...

Indycam

The little wires are easy to cross wire .

"I have relooked at the Mitchell Electric manual for the car and it looks like the blue wire D+ does not bring power to the alternator,"
So what do you think the D+ wire does ?

"the pos (current) goes from the battery to the starter then to the alternator. "
Nope . Boatowner's Mechanical and Electrical Manual by Nigel Calder
Good book for understanding alts .

JasonAndreas

The B+ wire (red) goes directly from the alternator to the starter (Term 30) and then straight to the battery. The D+ wire (blue) travels from the alternator out to pin #11 on the 14-pin connector in the engine fuse box and then to the alarm control unit (Term 61) and then from there it splits off to the ABS control unit and to the clock (pin #12) and from there to the central informer (pin #1).

If your alternator or the wiring between it and the fusebox was the problem your battery warning light on the clock should have illuminated when you grounded pin #11 in the engine fusebox! That's why I suggested to start there first and then work your way through the rest of the system. The fact that you have no warning lights when turning the ignition to start means there is problem with Term 15 from the ignition switch to the clock or with the clock itself? Which is what I think Loren was hinting at? Unfortunately (or rather fortunately for me) my alternator trouble-shooting experience is extremely limited.

Indycam

If the wires are switched so that the power is going to ground ?

CRG

[COLOR=DimGray]The little wires are easy to cross wire .

"I have relooked at the Mitchell Electric manual for the car and it looks like the blue wire D+ does not bring power to the alternator,"
So what do you think the D+ wire does ?

"the pos (current) goes from the battery to the starter then to the alternator. "
Nope . Boatowner's Mechanical and Electrical Manual by Nigel Calder
Good book for understanding alts .

Indycam-
According to the Mitchell manual,
The D+ runs from the alternator to the alarm control unit as a blue wire
From the Alarm Ctnl Unit it runs to the instrument cluster as a blue-red wire
From the instrument cluster to the Charge Indicator (in clock)
From the Charge Ind, along with the Oil Pres Ind, as a red-black to fuse #8 in FB 1

Also, it shows the red's coming from the battery and going to:
Radio, Fuse #1, Ignition Switch and Starter only
Then from the starter to alternator...

I'll have to check out the Boatowners book, this manual may be wrong?

either way, I really appreciate your and Jasons suggestions

Indycam

Its not a matter of the Mitchell book being right or wrong .

"I just dont know what the hell I'm lookin at with this wiring stuff, It's like I'm reading hieroglyphics.."

You need a Rosetta Stone so you can read the hieroglyphics
The boatowners has more info on how alts work , how to test them , why the wires are there , how to do tests to see whats wrong etc
If you find a copy of boatowners and read the alt section you will know the guts of alts .
I had a quick looksee , the book is in the Virginia Public Library system , not checked out .

"According to the Mitchell manual,
The D+ runs from the alternator to the alarm control unit as a blue wire
From the Alarm Ctnl Unit it runs to the instrument cluster as a blue-red wire
From the instrument cluster to the Charge Indicator (in clock)
From the Charge Ind, along with the Oil Pres Ind, as a red-black to fuse #8 in FB 1"

Ok , but what is its "job" and if you hooked up that wire to ground what would happen ?
Would the power straight to ground freak out the alarm control unit and cause it to shut down ?
Could that be the cause of no lights at all .

I've been a tech for over 20 years , part of my training was to go back to the thing you just did and double check it before looking elsewhere when problems pop up after a repair . Its proper teching .

Lorenfb

Like Jason said, the key is to ground pin 11 on the T30 block:

1. alt. light comes on - bad alt.
2. alt. light doesn't come on - no #15 power to the alt. light (clock inst.)

Indycam

Lorenfb
What happens if the wires are switched on the back of the alt ?
What happens if D+ is broken and of pinched to ground ?

Lorenfb

D+
1. broken - no alt. light & no charging
2. shorted to ground - light always on & no charging

D+ can't be switched with B+ as lugs are different.
If D+ switched/connected to ground, then #2 above.