Was advised to post over here about a problem I'm having with my 993. Here's the original thread link:
https://rennlist.com/forums/911-foru...l#post13712275

"Need some help diagnosing my 97 993. Here is what I can tell you:

Pulled the car out of the garage last week. Had the boot/doors open for a bit, nothing crazy long. Went to start it to take it out for the night and nothing. Lights come on, radio comes on, alarm arms/disarms but it doesn't crank, nada. We pushed it back in the garage and I did the following:

-Tried the other set of keys/fob. nope.
-replaced the DME relay. nope.
-pulled the battery and put it on the tender for a couple days. nope.

The only thing I can think of, based on some texting with the previous owner and my local guru, is that the ECU/M is not reading the immobilizer correctly and it's keeping the car "locked down". Can anyone help shed some light on what might be going on? I really REALLY don't want to spend north of $500 having the box flashed if I don't have to.

Thanks,
Joe"

 

very near the DME relay is a "start relay"
If you do not have start voltage present at the starter motor, try replacing the "start relay".

It is the same as 3 or 4 others in the tray, so you can just swap them around.

good luck.

 

Thank you!! I will try that as soon as I get home as I now have a "good" DME sitting around since the one I pulled is still functional.

 

more details better
what is the history of works on car? did it have immobilizer problems?
what other problems and what was fixed,
how many miles and what type of 993 is it?
did you lock it with immobilizer after no start?
are you sure the battery is good?
thanks

 

There's a decent service history on the car but nothing electrical related. The one thing that I would have to do when starting the car is arm then disarm the car before it would start.

128k on the clock, standard N/A 97 993
The fob will still arm/disarm the car even though it won't start. Battery is still reading above 12V, so that's decent.

 

do you hear anything with key on position 3 ? clicking in engine, fuel pump whine ?
do the dash lights fade a tad when you turn key to start position number 3 ?
what i mean by pos. 3 is :
position 1, key in
position 2 , dash lights
position 3 , cranks

 

Does your car have a clutch interlock switch? My '96 doesn't but I think they might have added that starting in with the '97 models (at least it is in the wiring diagrams for the '97-98 models). That might be faulty and preventing the starter relay from energizing.

GC

 

I would start with the basics....how old is the battery. What is the voltage?

You need over 12.4 to start it. Do you have a multi-meter? Does your battery have water or AGM. If water did you check to see if the cells are low on water?

You can pick up a cheap battery tester load for just over $20 bucks and good to have around.

 

Yes, 97 should have a clutch switch. When I faced starting issues, I did some research that I summarized in some trouble shooting tips here:

https://rennlist.com/forums/993-foru...metimes-2.html

You should get some electrical drawings for your model to help the process.

 

The VERY first thing to do here is check the no-load battery voltage and make sure its 12.66 VDC. Anything less is below 100% charge and an old battery may be sufficiently sulfated so that it won't start the engine. I've seen this far too many times to recount.

Check the date code on that battery to make sure its less than 5 years old. Anything beyond that is on borrowed time and may not work, even if charged.

If all that checks out OK, clean the battery terminals, clamps and ALL grounds so they are bright, shiny & clean.

 

I concur with GC96. Suggest you by-pass the clutch safety microswitch at the base of the clutch pedal assembly. If, after you do by-pass it and the car starts, there's your culprit.

 

As above. I had 98 with failed clutch relay with same symptoms. Easy to jump this to check. Good luck.

 

Jumping the start relay (R61) pins 87 & 30 eliminates the clutch switch,
the start relay and the immobilizer. This should allow the engine to crank.
The next step would be the typical troubleshooting of a no-start situation
described here under "No-Start";
http://www.systemsc.com/diagnostic.htm

 

I have/had a similar symptom—it was/is my ignition switch. Every once in a while something doesn't connect. I try 15 -20 times, taking the key in an out every two or three times and jiggle it a bit then, boom it starts, then it doesn't happen for another 6–8 months. Then it will happen 2 times in 3 days then nothing for a year. It has been like this for 4 years, I really should get it replaced, but it is so infrequent I haven bothered.

It drove my mechanic crazy though because it happened when he was trying to program a couple of remotes for me.

 

Can you elaborate on this? I might have time tomorrow night to dig into the car and this is the first thing I'm going to do. Being a small business owner is an 8 day a week job, lol, but I think I've carved out a little time tomorrow after work.