VS commodore stalled then won't start.... earth problem? No spark

[VS VS VS]

Hi, I have a 1995 VS Commodore sedan executive V6 Auto. Never had and real issues with the car since it was purchased in 1999. Crank angle sensor replaced 10 years ago(common fault-would not start when hot but would never stop while running). Couple of new radiators and a couple of new alternators.

The Issue.

I drove to work the other morning (heavy rain conditions)with no issues. After work, I got in the car and it started fine. Drove about 50 metres and the car stalled. It then turned over but would not start. Fuel gauge on 1/4 and you could hear the fuel pump. RACQ turned up and suspected low fuel. He put 10L in and then pulled one of the spark plug leads to test for spark. While testing for spark the car started. It was turned off, spark plug lead was replaced. The car started fine. RACQ suspected faulty fuel gauge so I drove about 2km to the petrol station, fuelled up but it only took 30L so there was plenty of fuel prior to the RACQ adding 10L. Drove another 500m and the car stalled and would not start. I had the car towed home.

I have the workshop manual (Ellery's- I don't like it much, Haynes was better until I lost it) so I tested spark. None on any plug. The next test was to ensure the pink wire on the DFI connector was connected to earth- It was not. All the manual follows up with is to check why the earth is faulty.

While looking for any earth points (ignition was on) i touched the oil pressure switch and relays in the engine bay started clicking on and off multiple times so I turned the ignition off. Could this just be because the battery was super low due to all the starting attempts(car would not turn over any more). I pulled all the coils off and tested primary and secondary resistance- All OK. Put ignition coils back together and tested the pink wire on the DFI again and the test light came on. There was no earth fault. Put the connector back on the DFI and the car started immediately and ran for 30 minutes without an issue.

Not only has the earth fault gone but the TACHO now works. It has not worked for 10 years and I never bothered to investigate why.

Questions??
Why would the TACO work after 10 years?
Where does the Pink wire go? I cant find it on the wiring diagram at all?
Any ideas on what could cause these symptoms?

Sorry for the long story but I thought the information might be relevant to the fault.

Thanks in advance..........

 

[greenacc]

Any error codes ?
I have a vs gregory's manual for sale if you need one.

 

[hako]

There is no pink wire to the DFI module in the wiring diagram as you quote. The relays clicking when you touched the oil pressure switch indicates either a bad connector or a bad switch - new ones are about $20 and I'd fit one as they do leak with age and also fail internally.