924 refuses to start - HELP please

[GBee]

Afternoon all, frustratingly my sons 924 2.0ltr all of a sudden refuses to start and so I thought I would post here in the hope somebody else has had a similar issue and could provide some insights.
The car was running fine with no Gremlins save for the headlights switching off then back on again on 2 occassions the previous day to when the problem occured.
Now the car will not turn over at all (battery ok), all ignition lights come on and contactors/relays can be heard to operate but nothing else. This to my knowledge hasn't occured before and I'm not sure what to check next, heater fan, windscreen wipers (inc rear wiper), side lights, brake and indicators all operate as does main beam flash but headlights will not come on (possibly because the engine is not running?).
I've replaced the ignition switch unit, the old one was split and wouldn't operate properly at the starting position but didn't hinder starting the car when it was running previously.
I haven't tested yet at the starter motor solenoid position as the heat shield requires removal but again this was fine until this problem occured, could this be an issue?

Finally does anyone know of a good mobile technician in the East Midlands area who could carry out diagnostics as the car can't be moved?
Regards and a Merry Christmas to all, though not so merry here at the moment
Graham

 

[vincematthews]

The car was running fine with no Gremlins save for the headlights switching off then back on again on 2 occassions the previous day to when the problem occured.

Check the electrical connector to the headlights which is at the o/s end of the raising and lowering mechanism. I've had this on a 944 where you're suddenly plunged into darkness for the sake of a poor or loose connection.

Now the car will not turn over at all (battery ok), all ignition lights come on and contactors/relays can be heard to operate but nothing else. This to my knowledge hasn't occured before and I'm not sure what to check next, heater fan, windscreen wipers (inc rear wiper), side lights, brake and indicators all operate as does main beam flash but headlights will not come on (possibly because the engine is not running?).
I've replaced the ignition switch unit, the old one was split and wouldn't operate properly at the starting position but didn't hinder starting the car when it was running previously.
I haven't tested yet at the starter motor solenoid position as the heat shield requires removal but again this was fine until this problem occured, could this be an issue?
Graham

Try starting the car with the lighting on, does it dim a lot? This could be the starter motor or its associated wiring which Porsche thoughtfully put near the exhaust system. You need to get underneath to check - ideally []
I've had to replace all the heavy gauge wiring to the starter on my car.

If it's the starter, you may be able to free it up by putting the car in gear and rocking it back and forward - obviously take it out of gear before seeing if you have been successful. If you can get access to the starter, giving it a whack with a mallet can work.
You don't say what age your car is, but if you do have to replace the starter, you may find you have to modify the wiring to match the modern replacement.

The other favourite is earthing issues. It's worth periodically taking the several earth straps off, cleaning the mating surfaces and where they are attached (including at the battery), and refitting.

Hope you're back on the road soon.

 

[scm924s]

Put a multimeter across the battery, check voltage before and during trying starter, if it drops, then as stated above, probably a starer/wiring issue. If it doesn't drop, put a jump lead between battery earth and a good earth point on the engine, lifting bracket is good, and try again.

Headlights are not dependent on engine running but should operate with ignition on, could be headlight switch.

 

[russmw]

Morning,

Worth checking the cabling that goes from the 3 pin multi-plug to the right of the coilin front of the battery that then goes down the back of the engine to the starter then the alternator. Due to the close proximity of the exhaust the cables get a really hard life. You should to be able to see then end of the cable that attaches to the starter if you look under the exhaust manifold from the front then see where it links off to the alternator (they share one of the cables).

If the cable has finally fallen to bits it may explain why the starter isnt doing anything. Should the cable need replacing you can buy pre-made looms online of if you're handy with cables make your own (I did as the cable on mine was wrecked!!)

good luck

 

[GBee]

Thanks for all your replies so far guys.
Will work my way through these tomorrow and see how I get on and post to let you all know how it all works out, many thanks for the suggestions so far.
The car was running just fine and there were no tell tale faults materialising but it was the sudden non-start that got me thinking of component failure, as I mentioned the headlights were and probably are a red herring.
Just to confirm the battery was a bit down on charge but I'd got some seriously hefty jumper cables linked up to my BMW X3 running on the drive so it wasn't short on power and even with this there was no starter motor activity whatsoever.
I've now changed the ignition switch but still no change so onto your combined list of suggestions.
Russ, was that your car car at the Bicester Christmas event?

Regards
Graham

 

[russmw]

Russ, was that your car car at the Bicester Christmas event?

Regards
Graham

Yes it was - asked if I wanted to be in the red or white line up so went with white. The two tone made it stand out a bit though

Regarding your car it sounds is if the starter motor isn't getting fired and the cars don't have the most complicated of electrics so I'd guess either the +ve lead to the starter or the igniter cable has corroded and detached itself. Getting the heat shields off involves a 8mm and 10mm socket once you have the car off the ground and only one of them is a bit fiddly to get to.

Good luck!

 

[GBee]

Thanks Russ,
I thought so I had my white Cayman R on the display towards the top end near the 356 display car, it was a great turnout.
Typically my son is out and not back home today so I can see me looking at this problem on my own so I'll tackle the heat shield next and check out that wiring, it's quite enjoyable really as I cant really tinker with the Cayman!
Cheers for now.
Graham

 

[GBee]

Just a quick update, finally sorted the issues on my sons 924.
I worked my way through all suggestions provided - thanks guys but non were the cause of my troubles of non starting but all were valid points to go through. I changed the ignition switch, it was damaged but not the cause of the problem, I also uncovered a relay that was failing (had water in it????) and changed that too but to no avail, starter cable and starter checked out all ok.
As I worked my way around different reference points checking for a live supply I started to suspect that the immobiliser was playing up, toad 2, as none of the key functions fuel pump, ecu, starter circuit were getting any power and also found a post on a vw forum stating exactly the same circumstances ie everything was fine 1 day and then nothing .....at all. As it turned out it was the immobiliser and it's now been removed and everything works as it should.
The one distraction or red herring was that the headlight lift motor connector block had deteriorated inside and finally ended up putting a permanent short onto the lighting circuit but no fuses blew? Once isolated I could tick that off and get the rest sorted so that was the fix for the intermittent headlight fault.
Sincere thanks for all your suggestions, it took longer than I had hoped but fortunately my son still had his other car to run around in so was more frustrating than anything else (so easy to say that when it's done )

 

[russmw]

Good news and well done on finding the problem.

I'm guessing the after market alarmsimmobilisers on these cars will now be hitting 30 years old so not surprising to see them dying a death. Now just need some dry and salt free roads to get the car out and drive.

 

[GBee]

Thanks Russ,
Feeling a lot happier now, it was a chance spot about the VW issue but I sort of put it to the back of my mind until I'd gone through everything else but in the end it didn't make sense not to be. As you said at 30yrs old it's got to be a suspect, good thing is it got me going around the car so became more familiar with it. I prefer leisurely tinkering where I can decide when I want to tackle something and not being under pressure to find a solution quickly, all worked out well in the end tho' .
I hope this post helps others in the future you can't beat the knowledge out here on the web.
Thanks again to all who provided ideas/advice.