As promised, I've written up what I know so far about replacing the relay board with something more reliable. Note that some of the details are from the Haynes Manual, in which I've already caught 2-3 small errors. I've not yet done this, but I intend to this summer.

See the blog for more.

QUOTE (lapuwali @ Jun 21 2005, 11:39 AM)

I've not yet done this, but I intend to this summer.

i'm sure you know that the main connectors and harness came in different configurations for different years ...

for example, not all main harnesses have the optional sport-o-matic wire.
also, the engine harnesses for different years have different wire configurations on the connector to the relay board.

oh, and if you look closely at the PIN numbers for the relays you'll notice a change between the years as well ...

Andy

Hey James....I have your transmission parts in the back of my truck, I'm headed over to redwood city right now....exit Seaport, are you close by??

if so, call me on my cell.....



now to your mods...

shouldn't the blue (G) wire connect to the VR??

Actually, at least up to '73, the 12 and 14 pin connections appear to be the same, at least from the (admittedly not all that accurate) Haynes manual. I expect L-Jet to be different (as I state). As for exact relay pin connections, that's not really relevant, since they're being completely replaced.

In any case, still a work in progress...Any specific differences I'd certainly like to hear about. I only have access to a '71 right now, so I can't verify anything in the manual other than that year.

QUOTE (Mueller @ Jun 21 2005, 11:00 AM)

now to your mods... shouldn't the blue (G) wire connect to the VR??

Yes, it says: blue to D+ on VR.

QUOTE (lapuwali @ Jun 21 2005, 11:02 AM)

Any specific differences I'd certainly like to hear about. I only have access to a '71 right now, so I can't verify anything in the manual other than that year.

The L-jet wiring is not really different from the D-jet wiring of the same year--unless you're talking about the engine wiring harness and the FI wiring harness, of course!

Different years handled the heater blower wiring differently, and possibly the fuel pump wiring as well. The 72s passed the oil temp sender's signal through the relay board, IIRC.

There are more differences as well but those are the ones that immediately come to mind.

--DD

Sounds like the only real way to figure out the actual differences would be to look at actual boards from different years. The Haynes manual shows the oil temp wire going through the relay board ONLY for '70-'71, and not for '72-'73. The '74 and later cars all have the current flow diagrams, which are much less useful.

I'd bet Jeff Bowlsby either knows all of this already, or he has relay boards from various years.

Of course, I could be wrong on the 72... And I wasn't aware that 70-71 cars had an option of an oil temp gauge in the first place!

--DD

James keep digging I'd love to get rid of the board thanks for doing this.

James

I don't know if you are considering making new boards but if you are maybe you could design a generic board that would include all of the routing possibilities and then people could use jumpers to select the features they need.

Dave

QUOTE (DNHunt @ Jun 21 2005, 04:46 PM)

I don't know if you are considering making new boards

what's wrong with the factory boards?

yes, some have failed (after 30 years!) but you can still buy the relay board brand spanking new from porsche ...

i did. and if it's going to last another 30 years, it was money well spend ...
Andy

I wasn't considering manufacturing anything, just providing directions for others. In your case, being an MS guy, the MS relay board kit should be very easy to adapt to the 914 in place of the stock relay board. It already has relays and fuses on it. If you're using the stock AAR, you don't need the IAC relay on the MS board, so you could use it for the blower motor, if you still have one. The board is $15, and the Digi-Key parts kit was roughly $40, as I recall.

Yep got it already.

Dave

QUOTE (SirAndy @ Jun 21 2005, 03:50 PM)

QUOTE (DNHunt @ Jun 21 2005, 04:46 PM) I don't know if you are considering making new boards what's wrong with the factory boards? yes, some have failed (after 30 years!) but you can still buy the relay board brand spanking new from porsche ... i did. and if it's going to last another 30 years, it was money well spend ... Andy

My primary motivation is to convert to aftermarket EFI, which will require some rewiring, enough that the relay board would be superfluous. I needed to understand all of the stock wiring to do this, as well.

But now that you ask:

The stock round relays are not locally stocked by most places, and they're like $20 a throw. A new replacement relay board is $350 from the Bird. The stock board uses those pointy-ended fuses I've had lots of trouble with on many cars for 20 years now. They don't have to be 30 years old to be bad, 5 years is enough.

30A 4-terminal relays are about $7 from Radio Shack, and can be picked up locally pretty much everywhere in the US. I can build a complete replacement board with all the parts on it (including ATO fuses, which I know from experience don't get flaky after only 2-3 years) in a waterproof case for under $100. This board would likely last 60 years of daily use in London weather, not just 30 in NoCal weather, and costs 1/3rd as much.

Automotive electrical technology has come a long way in 30 years.

QUOTE (lapuwali @ Jun 21 2005, 05:07 PM)

Automotive electrical technology has come a long way in 30 years.

well then, enough talk!

do us a favor and make them available and do yourself a favor and make some money on the side!
Andy