Porsche 964 DME relay problem

[mikedsilva]

The relay in my car is about 1 year old and today decided to stop starting.
I made some jumpers out of spade terminals, and sure enough, is starts perfectly, so I assume it is a bad relay. I order a new one.
The new one does not allow the car to start either.

Car is 1990, no airbags, and totally stock apart from cup bypass, and steve wong chip.

Any ideas where to look next?

[mikedsilva]

Well, I found this article on the 993 here on Pelican, and it shows a couple of checks.. pin 30 is supposed to get 12V with the key off, and I have that.
Then with the key on, pin 86 is also supposed to show voltage (the photo shows 12V) but I am only getting 1.3, sometimes 3V.. so I am thinking this is my problem.

Web searching leads me to think either alarm problem or ignition switch.

Alarm - I think it only has the factory alarm, but I don't know where the module is.. I removed both seats and under one seat is just the DME, and the other seat has either cruise control or spoiler etc (I cannot remember but I looked up the part numbers at the time)

Ignition switch - replacement does not look too hard, but a switch will cost me $200 here, so I am hoping that's the fix...

[mikedsilva]

Well, ignition switch has been swapped but still won't start.
Now I am getting 11V at terminal 86....The fact that has changed suggests I was on the right track but why the strange voltage readings??

[Flflyboy]

Suffering from same symptoms, final outcome?

[porsche964guy]

Originally Posted by mikedsilva

The relay in my car is about 1 year old and today decided to stop starting.
I made some jumpers out of spade terminals, and sure enough, is starts perfectly, so I assume it is a bad relay. I order a new one.
The new one does not allow the car to start either.

Car is 1990, no airbags, and totally stock apart from cup bypass, and steve wong chip.

Any ideas where to look next?

Genuine or Aftermarket. Don't rely on an aftermarket relay. They are notoriously bad new. So are aftermarket ignition switches. With the ignition on check and see if there's power to the fuel pump.

[porsche964guy]

Didn't hear if this issue was resolved.

This issue come up now and then so I thought I'd repost the bypass method.

you can bypass the relay with a couple of pieces of wire. In a real emergency you can get away with a couple of paperclips, but ideally you need a pair of jumper leads incorporating an eight-amp, in-line fuse. In the case of a flat-pin relay you need to place them across holes 3, 7 and 5 of the socket (corresponding to terminals 30, 87, and 87b of the relay itself), or from 86 to 87 and 87b if you have a round-pin relay. If the relay was faulty the engine should now start.

[BLACK3.2]

Get a solid state relay.

[mikedsilva]

Originally Posted by porsche964guy

Didn't hear if this issue was resolved.

.

For some reason, I don't get emails for this forum when a reply has been posted.
Yes, a new relay (again) fixed my issue..

[porsche964guy]

Originally Posted by mikedsilva

For some reason, I don't get emails for this forum when a reply has been posted.
Yes, a new relay (again) fixed my issue..

If you buy aftermarket keep a tested spare in the glove box.