Can you point me in right direction? Starting Issue
 

87 911 Carrera
Starting issue; battery is good (tested at local auto store), all lights come on the dash when starter key is turned but motor/crank does not even attempt to turn over when key is turned all the way to start. Starter is not activating......

Trying to diagnose with the basics first:
1) checked battery....it's all good
2) where do I go next to search of problem? ......starter relay maybe?

I'm thinking its something electrical between battery and starter but need direction on where to go next after battery check out fine......

TIA

I’d start here - https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/87-Starter_Troubleshoot/87-Starter_Troubleshoot.htm

Appreciate the link......
Will have to check the ground cable under the transmission and check the ignition switch.
Both are suspect b/c they are original/never been replaced.
I might just go throw an ignition switch at it since they are only $125 and who knows how many times that thing has been engaged/stressed since 1987!!!

would avoid throwing parts at this situation (especially something as complex as the ignition switch -- mine's got 190k on it and has never given me a problem) -- instead, work to isolate the source of the problem first -- should be straightforward to rule out (or confirm) starter switch by seeing if it passes current to the starter motor circuit when activated

When you turn key to starter position, do lights dim, or stay bright?

Most likely it is a bad ground. The yellow wire is the next thing to check.

Replacing the ignition switch is no fun, as you have to work with your head in the pedal box, in a very tight area.

I would put 12 Volts (fused) direct to the starter and see if it spins before replacing anything. If it spins, check the voltage of the yellow wire. After every ground from the battery to the transmission is cleaned and checked carefully.

When key is turned to starter position all dashboard lights are bright.......like normal....nothing dim, even the buzzer is loud

The more I thought about it, if ignition switch was bad wouldn't that mean I would not get any dashboard lights when attempting to start (giving the perception of a bad battery?).

Think I need to go back to ground at transmission......did a quick look and it is dirty from road dust, but I'm not able to get up underneath and check the connection yet .....if thats not the problem will follow GH85Carrera's suggestion

I just had a battery tested at the local autoparts store and they said it was good. I tested the car for a few days then turned my attention back to the battery. It would not keep a small light lit for more than 30 minutes. I took the battery to a store that specializes in batteries, and they told me it was junk. After a new battery, all is good.

The battery may not be your issue - my point is not to trust the simple auto parts store test.

as said above about the ground at the transmission...but it could be as simple as your yellow wire on the starter is disconnected....but in your case it should attached by a little bolt-unless someone already replaced it with a connector..
here
http://forums.pelicanparts.com/porsche-911-technical-forum/474216-image-starter-wiring-87-89-911-a.html

clean battery connections.

do you have a car alarm, aftermarket?
trash it if you do.

get a test light.
under the car at the starter,
ground it.
test it on the battery cable
check the yellow wire while someone starts it.
light should be as bright as the battery connection