I would like an opinion or two about the electrical problems I'm having before I start dissasembling anything.

It all started with an low engine oil alarm comming on and off. Oil sensor is now new (just to be sure).

The question is where to begin?

I think the instrument cluster is busted. Anyway the speedo works, rew counter works until the oil alarm comes than it drops to zerro.

The car runs but I would like to get it sorted.

If I have to change the instrument cluster is it an immo 2 or 3?

 

Any help would be greatly appreciated.

 

Thanks

 

Here is the VCDS scan

 

Chassis Type: 6N (6N - VW Polo (1995 > 2002))

-------------------------------------------------------------------------------
Address 01: Engine        Labels: 030-906-032-AUD.lbl
   Part No: 030 906 032 CG
   Component: ME7.5.10            3622 
   Coding: 00021
   Shop #: WSC 00788 
   VCID: 51AF05069B9E50964BD-5000

1 Fault Found:
18058 - Powertrain Data Bus
            P1650 - 35-00 - Missing Message from Instrument Cluster
Readiness: 0110 0101

-------------------------------------------------------------------------------

Address 17: Instruments        Labels: 6N0-920-xxx-17.lbl
   Part No: 6N0 920 804 E
   Component: KOMBIINSTRUMENT TRW V12 
   Coding: 00141
   Shop #: WSC 00006 
   VCID: 30696082F054399E243-5072

2 Faults Found:
01314 - Engine Control Module
            49-00 - No Communications
01321 - Control Module for Airbags (J234)
            49-00 - No Communications

-------------------------------------------------------------------------------
Address 19: CAN Gateway        Labels: 6N0-909-901-19.lbl
   Part No: 6N0 909 901
   Component: Gateway K<->CAN         
   Coding: 00020
   Shop #: WSC 00788 
   VCID: F0E92082B0D4F99EE43-5072

No fault code found.

-------------------------------------------------------------------------------
Address 25: Immobilizer        Labels: 6X0-953-257.lbl
   Part No: 6X0 953 257
   Component: IMMO                0008 
   Coding: 00001
   Shop #: WSC 00000 
   VCID: FDF709B6F78684F67F5-4A3A
   WVWZZZ6NZ1Y200945     VWZ1Z0Y1101492

No fault code found.

End   ---------------------------------------------------------------------

 

As you can see the VIN number in the Immob section 25 it's a immo 3 

 

To test the CAN bus from the speedo to the engine, remove the connector on the engine ECU and do a resistance check between pins 31 & 32 of the ECU it should be between 60 ~ 72 ohms, if it's outside this you need to replace the ECU if the resistance is within the limits, then I'd do a continuity check of the wiring from the speedo Green plug, Pin 20 should go to the ECU pin 32 & airbag controller pin 75, then Green plug pin 19 to ECU pin 31 & airbag pin 74

Thanks nige.

I'll check it as soon as I can. I'll report back then.

 

Does the CAN wiring go from the connector to the instrument cluster and from there to the engine and airbag controler? You don't have direct access to the airbag controller for example? Can a faulty ecu cause an error in the airbag controller?

thanks again

Edited 18 November, 20169 yr by cmat

The CANbus equipment, Engine, ABS, Airbag Climatronic, the two wires for each are all connected together and feed to the Speedo and the speedo outputs to the 16 pin diagnostic socket. It is possible and quite common for one or more of the units to fail and take down the data, so if those previous tests I suggested do not show a fault, reconnect one item at a time starting with the engine and see what happens

That's some useful info, thanks.

 

I'm a bit busy at the moment it's going to take a while to check what you said.

I'll report when it happens.

 

I'm a bit confused about the immo thing. If the CAN is down between ECU an instrument cluster and it's an immo 3 why it still works? It should loose connection with that too or not or it's just a disaster waiting to happen?;-)

I still haven't found the cause of the problems.

Here is what I have done:

Checked ECU - 67 ohm resistance on CAN pins (I can connect to it directly by choosing 'engine' in VCDS)

Instrument cluster - I can connect to it by choosing 'Instrument cluster' in VCDS

Airbag - cannot connect to it in any way.

 

Both instrument cluster and ecu show same error - no connection.... intermittent - with one anoter. This happens with no correlation to the airbag control module beeing connected or not.

Checked wiring from airbag unit to engine ecu on their CAN bus  pins seem to be ok. Measured only from airbag connector to ecu connector.

 

Could not open the dash (instrument cluster) to make measurements or check wiring there. Didn't want to break something so I left it for now.

 

Is there a guide or some  photos on how to take out the instrument cluster from a 6n2?? Very little info on the internet on a 6n2 cluster

 

Can I check the can bus on the airbag unit somehow?

 

Thanks for your time and help.

 

The resistance between pins 74 & 75 on the airbag should be between 2.35 & 2.85 K ohms

 

So you haven't done a continuity check on the canbus from the airbag to the instrument cluster ?

 

Here's a guide on how to remove the speedo cluster 6N2 Removing dash panel insert.doc

I did a check with a multimeter on both can wires from airbag connector to ecu connector. I didn't do it to the instrument cluster cause I culdn't get it removed. The instrument cluster 'roof' is a pain in the....

It's my girlfrend's car, If I break anything I Will be prosecuted.  

 

I measured the resistance on the airbag ecu is 2430 ohm.

 

I probably need to get behind the dash at this point, no other option.

What number are the 12V pins on the airbag ecu? At least I would like to see it on the VCDS.

Checked some earth leeds too, but no rust anywhere.

Edited 28 November, 20169 yr by cmat

The 12v supply is direct from the ignition switch to pin 26 and the ground is pin 51

Great thanks. I have only weekends to work on the car so will check as soon as I can.

If it has no power at least I have something to work on..

I was ill so culdn't work on the car and it was sent to a local garage.

Diagnosed as a bad instrument cluster, cluster repared and works ok atm.

 

Thanks for the help provided nige, anyway.

Edited 23 December, 20169 yr by cmat