HELP.......No Connection to ABS module VAGCOM

[MarkWilliams]

So, I've got a 05 plate Gt TDI 130pd and my ABS light is on with the 3 beeps. I've connected a VAGCOM I got from work and there says there is no connection to ABS controller. I've replaced the controller 3 times and also replaced the module and pump but still nothing. All fuses have been checked. I've had all the brakes done front and back including a clean of the calipers and the hand brake sorted as it's been sat for a while. Can anyone help PLEASE.

Thanks Mark

[littlepolo]

Silly question but does VCDS work otherwise? I'm assuming you are using a proper cable.

When you say all fuses have been checked, have you done a continuity test/replaced any?

Have you checked the wiring?

[MarkWilliams]

Hi, yeah all fuses have been tested. The VAGCOM is working correctly as it's from the mechanics at work. The wiring was the next step but I'm conscious of how much of a pain it might be. I didnt know if anyone else has had the same problem that had an obscure remedy. Thanks

[alexperkins]

Done the fuses on the battery too I assume?

[MarkWilliams]

Yeah. There is power getting to the controller but just doesn't want to be found by the VAGCOM. Going to get the wiring diagram for the ECU to the ABS controller and check those tomoro. Just need to find the diagram lol

[MarkWilliams]

So, all wires seem fine, power is getting to the module. What am I doing wrong/ what else could it be?

[littlepolo]

When Polo's get to this age they can do strange things electrically. I've had odd things happen, particularly in humid conditions. Any other electrical gremlins at all?
Any other codes?
Has anything else changed at all (e.g. stereo)?

Have you tested the pump motor alone (comparison between old and new)?
Can you access other modules with VCDS?
You said you checked the wiring - including grounds (e.g under battery tray)?
Battery cables firmly secured?
Brake fluid level OK?
Defective wheel speed sensor?

[MarkWilliams]

I've removed the stereo as it was an after market one. Checked all fuses and earth points, I've tried 4 different abs modules and 2 different abs pumps. The front brakes were replaced as were the rears. The brake wear sensor keeps beeping which is odd as they are new. The brake fluid level is topped up but still no luck.

[littlepolo]

You've checked the wiring under the battery box?
Have you tried an ECU reset? (doubt that it will work but possibly worth a try)

Not sure if the brake wear sensor affects ABS but it could be an indication of gremlins. To give you an example of some I experienced, the rear fog lamp and warning lamp comes on when I turn on the sidelights (the rear n/a sidelight comes on, but the rear o/s does not). Front n/s window goes down when I push the Front o/s, etc. This tends to happen more with humidity on the air so I think is indicative of moisture getting into the wiring/electrics and causing problems.

[MarkWilliams]

So the lights are still there after a full wire check, the abs light, the brake wear sensor light, power steering light and the red flashing handbrake indicator light after 3 beeps. I'm at a loss of what to do next.

What did your gremlins stem from?

Thanks

You've checked the wiring under the battery box?
Have you tried an ECU reset? (doubt that it will work but possibly worth a try)

Not sure if the brake wear sensor affects ABS but it could be an indication of gremlins. To give you an example of some I experienced, the rear fog lamp and warning lamp comes on when I turn on the sidelights (the rear n/a sidelight comes on, but the rear o/s does not). Front n/s window goes down when I push the Front o/s, etc. This tends to happen more with humidity on the air so I think is indicative of moisture getting into the wiring/electrics and causing problems.

[littlepolo]

Never got to the bottom of the problem with gremlins. I'm putting it in for investigation once I get other more pressing problems sorted. I expect it will be explainable (damaged wire or something like that).

[MarkWilliams]

Never got to the bottom of the problem with gremlins. I'm putting it in for investigation once I get other more pressing problems sorted. I expect it will be explainable (damaged wire or something like that).

Did you get this all sorted in the end?

I've had to have time away from it and have just managed to get back to taking a look. Was hoping for some inspiration.
I do feel like i'll be fighting a losing battle

[littlepolo]

Not yet. I have some pressing work to do prior to the MOT next month. Once that is sorted I'll ask the garage to have a look at the gremlins. It's a time sink and I cannot spend any more time on it myself.

[MarkWilliams]

SUCCESS

Finally got the correct wiring diagram for the car and found the culprit of ALL the issues.

It was a single wire between the fuse box on top of the battery and the Cambus. 30p worth or wire and tape and ALL the faults disappeared.

The Polo is now officially back on the road after 5 years of being broken (only 1 year under my ownership) but now glad she can finally scare the crap out of me and my wife whist driving around the Cotswolds.

Thanks to all who have helped and I hope this will help others in the future.

Mark

[iichel]

Good to year you solved it. Congratulations, good job. Winner takes it all.