Glow plug light flashing

Also worth giving your battery a good charge as a preventative measure. The 2 codes are connected. The ABS needs to see the brake switch to know if ABS is needed due to you braking or if it is traction control due to wheel slip.
 
Bad news, it is not the brake switch.

Clear the codes, turn on, apply the brakes, glow plug symbol starts flashing. Scan and the very same fault codes show on VCDS (see post Saturday at 11.20 AM).

I'm starting to think there is a wiring issue, with both old and new switches only the LED strip illuminates if I apply the brakes. The main brake lights do not illuminate.

With the brake pedal at rest the 6 LEDs to the left of the strip of LEDs glow but do not fully illuminate:
49255


Would anybody have a brake light wiring diagram so I can trace the fault or have any other suggestion?

Thank you
 
Finished with it for today, thought I'd do a few basic checks first:

Brake lights not coming on - check fuse - fuse is fine

Check rear N/S 6 LEDs not glowing with ignition switched on but brake light fuse removed, brake pedal at rest - still glow

Remove brake switch from circuit, ignition on, no brake light fuse - LEDs still glow

I'm calling it a day ?
 
Faulty earth wires often give strange symptoms - well they did on our Fiat Panda 4 x 4 (long gone)

Wiring diagms attached - think I've got all the brake light circuits covered

Cheers Spike

PS Just spotted one of the pics was duplicated. Now corrected
 

Attachments

  • A2brakelight2.JPG
    A2brakelight2.JPG
    82.2 KB · Views: 203
  • A2brakelight3.JPG
    A2brakelight3.JPG
    94.7 KB · Views: 205
  • A2brakelight1.JPG
    A2brakelight1.JPG
    75.6 KB · Views: 220
Last edited:
I was going to strip the back of the car down in frustration. Instead I will be taking a look at wiring diagrams and making notes of wire colours etc. Thanks @spike you have probably saved me from unnecessary work and expense.

I wonder if this could be the culprit? I the past it has stopped the fog lights from working.

49326
 
Phil,
Are the tow bar electrics factory fit/ done with bypass relay or just piggybacked?

Piggybacking or a dodgy earth as Spike says could explain the funnies.

Johm

Sent from my SM-G950F using Tapatalk
 
Another theory. Since the high level brake lights are LEDs, what would happen if the 'diode' bit on one of the LEDs fails and allows reverse current flow
 
Phil,
Are the tow bar electrics factory fit/ done with bypass relay or just piggybacked?

Piggybacking or a dodgy earth as Spike says could explain the funnies.

Johm

Sent from my SM-G950F using Tapatalk
The tow bar is factory, it has once before caused problems with the fog lights. Had to do some work down there, crushed wires and water ingress etc.
 
Last edited:
Another theory. Since the high level brake lights are LEDs, what would happen if the 'diode' bit on one of the LEDs fails and allows reverse current flow
Thinking about this one, in isolation yes, perhaps, however why have the main brake lights gone? Tricky one.
 
All I've done, besides wash and polish a dysfunctional A2, is study the wiring diagrams @spike posted thank you.

It's a surprisingly simple circuit with one feed to both the LED strip and the rear light clusters. The LED strip works but the light clusters don't. The only thing this could be is a break in the circuit after the LED strip (checked for two blown bulbs and earth issues). With the ignition turned on and the brake pedal at rest the LED strip is receiving a low voltage +ve feed from somewhere.

Could this feed find its way back to terminal 30 of the ABS controller and cause the implausible signal?

I also have my suspicions regarding where the implausible signal could originate from, look at pin 9:

.
Thoughts?
 
Just picked up on the fact you have a factory fit towbar so have added the extra wiring diagms

As part of the troubleshooting have you checked each live and earth at the brake light sockets

Cheers Spike
 

Attachments

  • A2tow1.JPG
    A2tow1.JPG
    129.1 KB · Views: 187
  • A2tow2.JPG
    A2tow2.JPG
    103.7 KB · Views: 193
  • A2tow3.JPG
    A2tow3.JPG
    125.1 KB · Views: 191
Back
Top