Aaaagh, non start, no brake lights

[mrnice]

Hi folks, started this in a new thread to attract more expert attention hopefully.

So yesterday I collected new amm from Audi, on drive home brake light warning came on dash. Noted to deal with later.

On returning home I disconnected battery and changed amm for new one, connected battery again then left car til this morning.

Now, engine turns over and nearly catches but not quite, battery voltage is at 11.7 with ignition off and I have no brake lights. No fault codes in vcds.
Vcds shows brake light going on and off as I press the pedal in grp 002 in abs/brakes.

Does the brake switch send a signal to ecu too?, maybe stopping me from starting car with no brake lights?

Any help appreciated!, damn car is across the pavement at bottom of our ridiculously steep driveway and unmovable!

[mrnice]

Ps battery now reading 11.87, I don't fully trust my multimeter though. The brake lights being fully dead seems too much of a coincidence to be unrelated though.
Perhaps me disconnecting battery while swapping amm is related though...
My main concern is I can't move the car until it's started.
Dead battery and or brake light switch are my suspicions.

Pulled nearly all fuses, all check out ok

[mrnice]

http://i1296.photobucket.com/albums/ag15/misternice23/Mobile%20Uploads/image_zpsohd4lumk.jpeg (http://s1296.photobucket.com/user/misternice23/media/Mobile%20Uploads/image_zpsohd4lumk.jpeg.html)
Here's the switch, it seems very loose and wiggly. Will replace this afternoon.

Here's the switch removed.
Confused as to any special installation instructions. Most say to insert & turn 45 degrees. This one was removed by turning it round and round anti-clockwise until free.

http://i1296.photobucket.com/albums/ag15/misternice23/Mobile%20Uploads/image_zpsfeni8fki.jpeg (http://s1296.photobucket.com/user/misternice23/media/Mobile%20Uploads/image_zpsfeni8fki.jpeg.html)

So it's an old style switch that needs turning in then adjusting to something like .5mm - 1.2mm between the plunger and body of switch. Got new switch & battery (old one 5 yrs old). Hoping for luck to happen.
Today is a bit sh1te so far.

[mrnice]

New battery and brake switch fitted and adjusted, same story. Was worth a shot I guess.
Now when I turn ignition on I'm getting the large red warning in dis and 3 beeps.
Nothing showing up in vcds in either engine or abs/brakes.
I've looked around the Internet and most folk have cured similar faults with new brake switch.

Engine catches for a moment with a squirt of brake cleaner. Might be time to book it into a good independent garage, any thoughts appreciated, could a fault in ecu or abs module cause this?

[ametlib]

You are not getting too much help here ? :) Check the cluster for fault codes .

[mrnice]

You are not getting too much help here ? :) Check the cluster for fault codes .
Thanks man, I'll double check but I don't think anything came up.
Tearing my hair out as I feel like it must be something simple..

[ametlib]

Just to sum up, you have the AWX wich is the PD engine ? So far you,ve changed the MAF sensor, only to discover your car then turned into a non starter ? Then you decided to throw away some money on the brake pedal switch and a new battery ? Right ?
Why did you decide to change the MAF in the first place ?

[bluezie]

If it's cranking and nearly catching, you most likely have air in the fuel, probably caused by an air leak in the fuel lines and made worse by the car being parked on a steep slope.
You could try rigging up a direct gravity fuel feed from a can to try and get it stared, but if it still doesn't it could be the tamdem pump has failed, or the injector O rings have failed. Have a look at the oil level is even possible on a slope, and look for excess level, and sniff through the oil filler for a smell of diesel.
Brake lights and MAF sensors will not cause a car to not start. BTW the brake light switch has 2 independent switches, the one you see in VCDS is the engine ECU switch, and the other operates the brake lights.

[mrnice]

Just to clarify, I replaced the maf sensor as a possible cure for some rough running- an intermittent misfire/hesitation.

But I had a brake light warning come on before I parked up and changed maf so logic would say it's not necessarily related. I had the battery disconnected while changing the maf.

I changed the brake switch as it's cheap and I changed the battery as it was giving low voltage readings, think that was fairly logical to start with.

Since I'd not touched the maf before the brake light warning came on while driving I don't suppose it's necessarily related.

Bluezie, that was my thoughts on the maf as it should start without it even connected.

All other electrics are working fine, it's not immobiliser as the light goes out and engine would catch first. In the cluster I get the big exclamation mark symbol and abs a esp yellow symbols on turning the key, then a further brake light warning when pressing brake pedal.

Thanks for the suggestions and advice, I'll have a good few things to check tomorrow when I have time. No time to look at car today so just theorising.

[mrnice]

Another wee thing-
Dis says fault in abs braking system when pressing check button.
Vcds finds no fault.

Am I right in thinking the abs module takes a signal of some sort from maf?

[ceilidhalfie]

For what it is worth - few years back I replaced brake light switch on my 2002 Allroad. Failed switch was old one - inserted it and turned 45° installed AND primed the switch. Replacement inserted and turned 45° to install - THEN TURNED A FURTHER 45° TO PRIME.
Having said that, car would start even with faulty switch.
(From memory - donot try to remove new switch as they are one time install!)

[mrnice]

I was reading up on that before replacing the switch, I did one a bit like that on my old Bmw, turns out mine had the old type switch that you have to adjust

[Col]

You do not have much luck!

I've had one and a half faulty brake light switches over the last twelve years of driving PD engined VW's. First one was a 2001 Golf, all that happened was the brake lights stopped working unknown to me at the time and the glowplug light started flashing on the cluster. It was only after getting it scanned I found out about the brake lights. The other half time was about three years ago on my current Passat, also an AWX engine. On the Passat it brought on the ABS and ESP lights on the cluster. Bought a new switch but by then the all was back to normal so I've never fitted it.

Both times it never effected the starting and running of the car. Maybe the VW's are wired slightly differently although they share the same engines.


As for the current problem of it not starting no idea really. If it was fuelling related you'd not expect to hear the beeps and have the warnings as the fuel system is almost purely mechanical with nothing feeding back to the ECU except for fuel temp. I would speculate that the in tank lift pump only receives an on/off supply from the ECU but isn't feed any data back to the ECU, it is afterall hust a pump.

And as there are no fault codes it makes it rather tricky. I assume VCDS can log into and communicate with all the systems? i.e. Engine, Instruments, ABS etc?

To be clear as well, the non start, is it happening with the old MAF, the new MAF or both?

[mrnice]

Hi Col, many thanks for the suggestions, yes vcds communicates fine with engine and abs and reports no faults (even though the car itself is screaming at me that there's an abs fault), need to double check on the whether it can interrogate instruments, coil light isn't staying on, just abs and esp.
That's right non-start with old and new maf so I've ruled out that as cause although I can't Say the same for maf wiring which looked slightly iffy, but then again car should start without maf anyhow...
On vag-cat diagrams there's no in-tank pump on my car but that's another thing on the long list for me to check tomorrow (I'll be busy!).

I may be looking at multiple issues here but it's odd they should all spring up at once.

[Col]

My random guess for the day is...

Dodgy relay, the one that powers the ECU and probably the ABS...

A complete guess though!

[ametlib]

Sounds like you need to take a look on the fuel supply/ tandem pump . . .

[mrnice]

Thanks folks, noted for tomorrow.

[mrnice]

So I had 2 dead brake light bulbs and an extremely corroded rear fog light bulb holder. Plus the high level brake light wasn't working. And 4.5 ish volts at the brake light bulb contacts, plus glow plug symbol flashing after about 30 sec of ignition on.
And a 'brake light switch implausible signal fault' in engine module in vcds.
Isolated the wires to fog light housing til I can get a new holder, put 2 new bulbs in and readjusted the new brake light switch until it no longer threw the code. Now all brake lights working.

Re the non-start-
As per a few suggestions-
No fault codes for cluster in vcds.
Checked oil for diesel and diesel for oil, fuel filter was full and fuel clean, oil level normal and no diesel smell.
Lift pump gargling as normal, checked it squirted a bit from feed line to filter (60ml or so) when turning key.
Fuel return line from tandem pump squirted a good amount on cranking too (60ml in about 8secs of cranking).
Still not even so much as a cough when cranking.
219 relay in ecu box seemed fine too, in that it clicked on and off with ignition and its innards looked fine with no burnt contacts. No water ingress either. I'd already sealed the base of the box to the plenum chamber.
Every fuse I could find under dash & bonnet intact.
Then I had a root around earth points in the engine bay, found one adjacent to abs pump & coolant tank that looked slightly furry and corroded. Gave it a good clean with emery and tightened up, car fired up immediately.

Earth point-

http://i1296.photobucket.com/albums/ag15/misternice23/Mobile%20Uploads/image_zpsnm3aoc1j.jpeg (http://s1296.photobucket.com/user/misternice23/media/Mobile%20Uploads/image_zpsnm3aoc1j.jpeg.html)

The two earth wires seem to serve ecu and abs module but I'm not sure what else.
It seems a little implausible that this wouldn't throw a fault code, but I checked and with the nut loose, car would turn over but not start.

Thanks for all the helpful suggestions, very much appreciated

[Col]

Tell you what...

Next time, i'll just keep quiet!

Who'd have thought that, makes perfect sense and is also good old fashion lateral thinking. I'll be keeping an eye on that earth point on my Passat which shares exactly the same mechanicals.


[edit] for many, those faults would have seen the car off to be sold as 'spares or repairs' or to the scrapper. A couple of, in hindsight, very easy repairs but many would not have the nounce to even think of them. Top top work.

[mrnice]

Thanks Col, not a very scientific diagnosis but it goes. Nothing more useless than a car that won't start..

[ametlib]

Veery good !!! I can't say this better than Col so "for many, those faults would have seen the car off to be sold as 'spares or repairs' or to the scrapper. A couple of, in hindsight, very easy repairs but many would not have the nounce to even think of them. Top top work."

If you have towed this car to an Audi garage I wouldn't be too surprized if they had replaced the following stuff,in this order- Battery, ECU, Injector loom, crank sensor and starter motor. Then they would advice you too scrap it !! :):)0)

[bluezie]

Are you using a genuine VCDS cable and software? I'm VERY surprised no codes have been logged in any modules, as this sort of fault normally triggers hundreds of codes in all sorts of modules.
If an ECU triggers warnings in the dash, especially red ones, there should be codes logged.
3rd party cables have a nasty habit of not extracting all the codes form ECU's.

[mrnice]

Nope, using vcds lite, 3rd party cable, it can connect to all controllers fine (after setting up port latency in Windows), there were a multitude of ecu & abs fault codes during my pulling fuses and relays etc but of course I cleared them in turn after each test. I had an intermittent code relating to abs signal from ecu at one point but can't remember exactly what it was. With the Earth cables disconnected of course vcds wouldn't connect to ecu or abs and a few relays went all spasmodic and the cluster went mental, With them connected but a bit loose (as it was before discovering it), all seemed normal but non start.
Someone with more experience and skill might know precisely what was happening here and what else, if anything uses this earth point and how a bad/intermittent earth would affect it.
I'm not beyond being suspicious that the earth cable was just coincidental, with something else eg in the fuel system going on that 'fixed itself' at the same time. At present I'm content with a car that starts and goes, though maybe I'll experiment with parking face-up the very steep drive and leave for a couple of days, or maybe life's too short..., good points though