Ok, I feel like an idiot asking this because I am obviously missing something. How do you know what the wiring is for the A-Z 8 pin connectors? I have a 1984 Porsche 928S and right now the only way I can see doing this is to do a continuity test on all of the fuses and relays. I feel like I am missing something simple to know what these are. Thank you for your help.

 

For that you need to read the Wiring Diagrams for your year in the Factory Workshop Manuals - you can get these in an electronic format from Roger (ROG100) at a reasonable price - the actual factory workshop manuals are many hundreds of dollars.

Alan

 

Would anyone mind walking me through this quick? Let's say I wanted to find out what wire was in connector Q, pin 4. On the left side of the connector it shows XVIII, so I would assume that is showing it draws power from that relay, so it controls the additional fan. On the right side it says J4, G26. I assume these are the items that it is providing power to. So then looking a few pages down at section J4 it shows Auxiliary air valve and cold start valve. Then more pages down is G26 and it shows it going into a wire harness that I think would power the coolant thermo switch and refrigerant regulator. Is that correct the way I am reading this?

At the end of the day, I am really trying to figure out where the tachometer wire is going.

Thank you so much for any input.

 

Try reading the Wiring Diagram Primer

928-electrics.com/wiring%20diagram%20primers.htm

If you can wait a few days I’ll give you more details - I’m away from home without a computer at the moment.

Alan

 

Thank you Alan. I printed it out and will be reviewing it this weekend.

 

You have the right idea. My diagrams for 84 show the inside (within Central Electric) connection to XVIII 85 and the outside (wire on the plug) going to Grid G26 (only).

XVIII 85 means pin 85 (the relay coil ground) for Relay XVIII (Additional Fan Relay). This relay gets its coil positive (86) from Fuse #7 output (top connection). the relay's switch (30) connects to Fuse #16 output (top connection) and the switch output (87) connects to CE pin Q3 and on to Grid K26 for the Additional Fan.
The connections @ Grid G26 (that is labelled Q4) goes to the common terminal of both the Coolant Thermo Switch and the Refrigerant Temp Regulator. Both of these connect to ground on their other terminal so either one connecting turns the fan relay on. So the fan comes on when to coolant is too hot OR if the refrigerant is too hot.

The Tachometer has many connections starting on CE: G7, O7, X6 Relays: IX 31b (kick down), XVII 31b (fuel pump [tachymetric]) Grids: C5 (speed sensor*), F9 (tacho instrument)

*there is no proper tagged reference here - a shortcoming of the diagrams for this model year)

If you continue to have issues with this create a separate thread on this topic and tag me @Alan or PM me about it.

Alan

 

Alan,

I am embarrassed. I found in this thread that I'd volunteered to verify the '94 GTS panel, then never did it. Unfortunately, the '94 GTS left about 7 years ago, so please take my name off that 'responsibility'.

I will try to make it up to you et al by doing a check of the '95 GTS if no one has volunteered for it (or done it) yet. The downside on completing the '95, however is it might be into October before I get it done. I'm now away from home for about a month - a few time zones west of you - and when I return, it's unlikely I can get it done for about 2-3 weeks. I WILL do it, however if you still need it.

Cheers mate,

Gary Knox
West Chester, PA

 

Gary - not problem - I have a '94 GTS so that was not a priority for me - I don't think '95 is different - but - YES Please do it anyway - more eyes are better!

Alan