I'll try that now, it's only a tenner at the shop down the road, so, on me bike again. This dead car thing is getting me fit at least!
Not really, don't know where to start to be honest. I checked the wiring to the coil and it was getting 12V but the AA guy reckoned the wiring to the hall sender was faulty- do you know which pins these go to on the ecu connector? Or better yet have a relevant diagram?
Not really! Earth faults on those make the ECU give problems, which don't show up as fault codes. These faults also can't be detected from the information in Haynes, etc. This is about the only VW substitution solution for the man in the street. Unless you know how to find earth faults.....
indeed, theyu can also fail intermittantly so test out ok but make the car a pain to start. i had an issue on my digi where it would never fire the 1st turn o the key, sensor tested ok and was fine once running, but issue was solved with a new sensor.
This is probably a daft question, but would the engine normally start if the temp sensor was unplugged? I did a bit more VAGCOM stuff with measuring blocks and it came back with this: ENGINE injection time 99.96 battery 11.78V air intake sensor 18C coolant sensor -7C ajust cond 00000001 throttle angle 5.5 throttle regl 50.8% all- engine sender 61.0 immobiliser auth start 1 ecu answers 1 key cond 1 no matched keys N/A So the immobiliser is definately working fine. Would the battery (bloody new one too) reading 11.78V be a problem?
I checked the 3 wires form the hall sensor to ecu connector, all have continuity to there, but the earth one doesn't have continuity to the engine block. Could that be the thing? Someone said earlier that it should have continuity to eath.
mk2 digi 8v is a real pain to start with the sender unplugged, need to give it lots of revs and even then its a struggle. The brown/white wire (pin 1) should be earthed to the block yeah, are there any loose brown wires near the side of the head/front of block near altternator?
Couldn't see any, There are 2 earth points left of the knock sensor on the front of the block. I cleaned them up really well and tightened them up already. I'll try checking where they go and testing them too next. Hopefully one of them is supposed to connect to the hall sender earth. Would it be a bad idea to connect the hall sender earth to the block with an extra wire? I presume all it needs is to be earthed?
lookin at some of my diagrams some cars have it earthed to the block, on others its earthed to the ECU instead!
It is connected to the ECU on mine, should it not still have continuity to the block? I didn't check if it changed with the ignition switched on, I'm a bit out o me depth here mind!
I think on my mates ABF this wire was only running to the ECU, I recall when it wouldn't start due to the immobilisor checking earth continuity and thinking it was a damaged wire, then realising that it was actually earthed to the ECU instead. I left the wire and it firted right up once the keys were recoded!
Just been looking at the diagram for mine, it's connected to the "sender earth" and point 35 on the ecu connector. Any ideas where the sender earth might be? I noticed there is a splitter on the earth wire between the hall sender and the 28 pin connector on the engine. The one going to the ECU is fine, maybe it's the other one?
i think this refers to the earth wire on the ecu temp sensor? I'm sure this wire on my mates abf ran to pretty much all the sensor earths on the engine loom and then to ecu plug.
You are right- had a closer look. progress! Well sort of. I put an extra earth strap from the battery negative to the block (same route as the original one) and it fired once or twice. I noticed that there was a voltage drop from measuring the battery voltage and then the coil input wires (over 1/2 a volt) before trying this. Would I be better off replacing the old one altogether or would adding one have the same effect?
looks liek you're close to makeing a breakthru! I'd have all the battery/alt/starter cables off and give em a damn good clean. the battery earth also runs to the battery tray so chekc that hasnt gone all rusty while you're there.Also if you take out the driver & passenger dash undertrays off I think there should be an earth point ot the chassis just below the dash either side, checkthese out too. I'd also run a fresh earth wire from here to the big round metal earth 'claw' next to/above the glove box, and check round the back of the fusebox for any loose chunky live/earth wires.
The battery is nearly flat now, guess I'll have to shell out for a charger. So, across the battery terminals it reads 12.1V at the coil 11.94V and in VAGCOM 11.78V. I'll have to charge it before trying again. Cleaned up all the main leads and terminals under the bonnet. Do I have to take the dash off to find this "claw" thing? 5 spanners in haynes! Scary.
Had a closer look at one of the main earth lead battery ends and started scraping away the coroded stuff- when I was finished there was practically nothing left of the wire! I think the term is "school boy error!" Off to the scrappy now.
I found a VW caddy at the scrappy and replaced the 2 main earth wires from the battery. Put a new temp sensor in (reading 16C which seems bang on) and it still won't start! Not even a hint. Thinking of going back to the scrappy and seeing what he wants for the caddy- probably easier to fix!!!!!
