Caddy 2012 1.6tdi - Wonts Start (Dash, ignition, and some other things all dead)

[aliS]

Evening All,

I have a 2012 caddy that is dead to the world. With no prior warning and after sittign for 5 days I went to start it in the morning and after turning over the engine for 1/2-1second every thing went dead. I recycled the ignition and it started without issue. I then drove 12miles to work and the dash would flicker on and off ever so often for about 1 second with no apparant loss of power or headlights but the instrument cluster would go on and off (no fading just on and off). Driving back from work no issues until 7 miles when everything cut out at 70mph and on second or thrid attemot restarted (after about 10 seconds) - I think the engine was still running but I couldnt be sure. I then parked up at a friends house near buy and checked the fuses and relays for anything obvious. Attempting to recommence driving and then the dash would light up like an iginition sequence following 1-2 second loss of power whilst driving away so I turned round and parked the van up.

I suspected an ignition switch failure due to the lighting sequence and thought I'd just try changing that - two days later I've changed the ignition and nothing. The symptoms I have are as follows:
- no dash lights at all (no odo or background light)
- no reponse from any ignition switch - voltage at ignition switch 0.9v
- side lights will work as will internal but nothing else
- No hazard lights
- radio ok,
- electric windows wont work of switches, will come down on the key fob but will not go back up, key in the lock will put windows up and down
- battery + to body earth 12.45v
- each positive of fuse box in engine bay to body earth 12.45v
- relays 100 under bonnet switched out for known good relay with no effect
- relays 646 and 645's rotated round positions to no effect
- relay 644 changed out for known good relay with no effect

This is as far as I've got as the van is abandoned at a friends, I don't have a code reader and just now I have no money to get it into a garage for someone to have a look at (I've just started a new job after several months off work so am strapped for cash). My gut instinct is that whatever provides power to the above circuits that are dead to the world has failed/parted or shorted out - would anyone suggest where to look?

Does this sound familiar to anyone?

Thanks in advance,

Ali

[aliS]

Hi again,

I’ve managed to get a code reader onto the car but it will not communicate (possible as I can’t turn the ignition). I’ve checked the ECU & BCM for obvious damage and loose wires to no avail.

I’ve routed around with a multi meter but starting to loose the plot with this.

Any ideas how I can read the codes? Will a particular type of reader be able to interrogate and ecu that is not powered.

Circuit boards in cam bus and BCM look ok.

[VAG-Abound]

Code reader should work witb ignition in ACC position, so no need to start engine. Jump leads from other running vehicle?

[VAG-Abound]

Ah, I see the problem. I think I'd pull radio and bring 12V from battery to perm and switched lead via fuse carrier from *********, spade terminals to loose fuse, etc. Or a spare terminal on the supply side og the fuse rack. Hopefully that'll get juice to control units.

[aliS]

I had wanted to do that but was concerned I might fry something...

[VAG-Abound]

That's why I'd put a fuse in the feed from battery. To check in advance for obvious problem check resistance from wherever you want to connect 12V to ground. Should be noticeably non-zero.

[aliS]

That's why I'd put a fuse in the feed from battery. To check in advance for obvious problem check resistance from wherever you want to connect 12V to ground. Should be noticeably non-zero.

Piggy backed a fused power feed out of the cigarette lighter to the ignition, managed to get the OBD II scanner to interact but no stored or pending codes found. P026 came up when the ignition was on but I think that was more to do with only having half the system to life. Couldn't start the car of the piggy back when introducing the last cable of the ignition sequence to the power source.

I had 644 and one of the three 645 relays function hotwiring the ignition but no function from the other two 645 or the 464/646 relays beside the steering wheel column. Dash lights never came on and only the blower seems to come to life.

Would the ECU and BCM always throw a code up?

My gut instinct is still water having shorted out something but still cant see anything for the love of me.

the voltage supply to the ignition is <1.0v and the 3 switches off which the single supply functions
hat have low impedance.

Any ideas where to start next?

[aliS]

As a quick update after suspecting the instrument cluster could possibly be the culprit I checked the connector to the cluster which was completely dead with perm live reading only 0.1v and the other two switches supplies reading 0L.

So my problem is between the + batt to ignition. Will trace the cables back this weekend

[Crasher]

You need to find out if it is the code reader or the car, that will show you where to start.

[aliS]

Thanks Crasher, a friend who works for a local vag specialist tried to read the codes to no avail also. After 5-6 weeks having forgotten about the van due to work and family commitments I spent a bit of time today checking out the ecu and connections and also the fuse box under the bonnet for the obvious - all connections where live Barr the fuses supplied from 100 fuel pump relay.

Will keep digging tomorrow -

[aliS]

In my digging I’ve checked out all fuse boards to make sure they where all ok. With the battery removed I checked impedance accross each of the larger feeds out of the front of the fuse box in the bonnet with the 80amp power steering feed being a bit odd. Occasionally continuity but more typically 1.5ohms and up to out of limits all this happening without any input to the steering.

Could a short - live to earth be responsible for the total loss of power? If so why are no fuses blown and would any one know the resistance accross the power steering motor?

[Crasher]

You can’t check the power steering controller that way.

[VAG-Abound]

EDIT:Removed mistaken reference to starter motors.

[aliS]

You can’t check the power steering controller that way.

Was just looking for shorts that might be cause for no power to the vehicle, just found it strange the way the resistance ran. Surely with no power it would just give a consistent reading?

[VAG-Abound]

Without looking at wiring diagram to check I'm wondering if a failt in supply to / from X relay (100?) would kill tbe bits you see going off while keeping a few bits working. Not sure it woukd leave near zero V at ignition though... I suppose that could be fault in what it switches, or switching input drufting and killing output at wrong times.

[aliS]

Without looking at wiring diagram to check I'm wondering if a failt in supply to / from X relay (100?) would kill tbe bits you see going off while keeping a few bits working. Not sure it woukd leave near zero V at ignition though... I suppose that could be fault in what it switches, or switching input drufting and killing output at wrong times.

cranking The ignition functions that relay so no supply at the ignition is eliminates that from fault?! I don’t like wiring... a few more hours this week then it’s going on a trailer.

[VAG-Abound]

Not sure if cranking pozition on ignition is fed from permanent supply, while other positions are fed from X relay . If you replaced it you probably do know.

If it does have permanent and X supplies then relay remaining open intermittently and then more constantly due to mechanical or electrical fault could fit. Except it would still crank OK...

[VAG-Abound]

Looking at a same year Touran (it was all I could find...) the 12V supply for ignition switch is from J527 module under steering wheel on a violet wire, which in turn is fed by a red/yellow wire from SB6, via connectors in the main wiring harness.

Does that fit what you saw when refitting ignition switch? Not sure if Caddy's might have kept earlier Touran wiring for a bit longer.

EDIT: SB6 also feeds instrument cluster, which seems consistent with lack of activity you're seeing there. If you can unplug connector on it and 12V comes back to ignition it helps figure out which might have a fault to earth. And vice versa of course.

Then checking that with fuse removed output from SB6 has good connection to J527 and instrument cluster, but no connection to earth. There's a set of three a loom connectors that it travels uhrough under driver relays in the diagrams. Pin 13 on leftmost (C) was the one I think.

[VAG-Abound]

Just thinking about this a bit more. The small voltage you get at ignition suggests one of:

It's a floating current from somewhere else which I think would remain if you remove B6
It is the remaining voltage after a high resistsnce joint between B6 and ignition has dropped 90% or so of volts in which case voltage at ignotion would go to zero when B6 removed.

[arcadius82]

Hello Everyone.

I have VW Touran 2012 1.6TDi with excatlly the same issue like VW CADDY 1.6 above.

1. No ignition, No cranking, no starting.
2. DASH - no light up complete dead / but tested on bench working fine.
3. No communication with any modules / but on bench no problem example with ECU PCR1.6 or Dash
4. Nothing happened when ignition on or key in ignition. / only working remote
5. Working only radio
6. Tried new set ECU, BCM, Fuse box under bonnet, dash, Can module, ignition barrel, squib module / still no communication
7. download diagram from VW ERWIN / check all wiring im in point that i not getting ignition 12v via relay from BCM

Wants to go forward and get more diagrams to find issue. If i simulate ignition relay then im getting communication with ECU via OBD but Dash still death, I can simulate as well after starter relay but of course will not fire as no communication with other modules ECU - BCM - DASH - KEY

Did somebody solve this simillar issue.

Regards
Arek

[Crasher]

Sounds like the line 15 relay is faulty, I had this on a Golf 7 a couple of weeks ago.

[aliS]

Crashed/VAG bound thanks for your feedback input so far. Apologise I have not replied, with all that’s been going on I have been on an emergency roster at work and child care at home with the caddy stuck at her parents (venerable) preventing me spending time on it.

Thankfully though trailering it back home tomorrow so fingers crossed getting it at home will give me time to get to the bottom of this.

Cheers,

Alo

[aliS]

Hi Arek, I’ve just got my van home after 2-3 months of being abandoned at the in laws. Will let you know how I get on but you do sound like you have the same if not very similar issue.


Hello Everyone.

I have VW Touran 2012 1.6TDi with excatlly the same issue like VW CADDY 1.6 above.

1. No ignition, No cranking, no starting.
2. DASH - no light up complete dead / but tested on bench working fine.
3. No communication with any modules / but on bench no problem example with ECU PCR1.6 or Dash
4. Nothing happened when ignition on or key in ignition. / only working remote
5. Working only radio
6. Tried new set ECU, BCM, Fuse box under bonnet, dash, Can module, ignition barrel, squib module / still no communication
7. download diagram from VW ERWIN / check all wiring im in point that i not getting ignition 12v via relay from BCM

Wants to go forward and get more diagrams to find issue. If i simulate ignition relay then im getting communication with ECU via OBD but Dash still death, I can simulate as well after starter relay but of course will not fire as no communication with other modules ECU - BCM - DASH - KEY

Did somebody solve this simillar issue.

Regards
Arek

[aliS]

Hello Everyone.

I have VW Touran 2012 1.6TDi with excatlly the same issue like VW CADDY 1.6 above.

1. No ignition, No cranking, no starting.
2. DASH - no light up complete dead / but tested on bench working fine.
3. No communication with any modules / but on bench no problem example with ECU PCR1.6 or Dash
4. Nothing happened when ignition on or key in ignition. / only working remote
5. Working only radio
6. Tried new set ECU, BCM, Fuse box under bonnet, dash, Can module, ignition barrel, squib module / still no communication
7. download diagram from VW ERWIN / check all wiring im in point that i not getting ignition 12v via relay from BCM

Wants to go forward and get more diagrams to find issue. If i simulate ignition relay then im getting communication with ECU via OBD but Dash still death, I can simulate as well after starter relay but of course will not fire as no communication with other modules ECU - BCM - DASH - KEY

Did somebody solve this simillar issue.

Regards
Arek


Just thinking about this a bit more. The small voltage you get at ignition suggests one of:

It's a floating current from somewhere else which I think would remain if you remove B6
It is the remaining voltage after a high resistsnce joint between B6 and ignition has dropped 90% or so of volts in which case voltage at ignotion would go to zero when B6 removed.


Oddly whilst starting to run through the van I found 0.5v running on the red/yellow feeding into the steering module before the ignition switch. When I unplugged the instrument cluster this jumped to 5.8v. Bearing in mind the instrument cluster is completely dead I’m left scratching my head as if it was a fault to earth with the cluster surely I’d have 12v back at red/yellow when disconnected or nothing at all. Connector for cluster seems fine with no shorts there.

Update: I charged the battery as the van had been sitting for a few months now and the red/yellow voltage is 11.9 with cluster removed and 0.5 fitted. So I guess it’s a complete cluster failure.

[aliS]

Wasn’t the cluster after all - came back no fault found.

[aliS]

ISSUE RESOLVED:

After finally getting some annual leave I managed to get stuck into the van, the first time since the instrument cluster came back with no fault found.

Having recharged the battery I started looking again, with 12v remaining at red/yellow feed at steering module with out instrument cluster and dropping to 0v with instrument cluster plugged in.

Measured resistance from SB 6 supplying fuse in engine compartment to cluster/steering module with cluster removed read 0.5 M ohms. Removed dash and hunted for cable damage. Eventually cut the red/yellow where it passed through bulkhead and measured either side with high resistance between fuse box and bulk head. Unwilling to completely remove the loom at this point to investigate I ran a new 5a cable and soldered/heat shrunk in. Rebuilt dash and van started, initially rough with various lights clearing after a few minutes.

Thanks to all for feedback especially VAG bound who really hit the nail on the head where to look.

Thanks,

Ali