Differential lock issue.

[Chris Brett]

Hi guys I own a 2018 T6 Highline 4 motion T32 204 DSG Kombi.
Just developed a problem unfortunately in the last 2 weeks.
The differential lock comes on for 3 minutes when ignition is switched on. Won’t switch off with button during the 3 minutes but after that & the light goes out I can switch it on & off without an issue with the dash switch.
After it’s recent full service & cam belt water pump etc, gearbox fluid service at VW Cowfold Sussex (southern motor group). No fault codes showing.
VW master tech has just checked it all out and found nothing. He’s saying that the last thing to check/ replace is the relay on the differential.
Unfortunately this involves exhaust removal & rear axle lowering. Costly.
Any advice would be greatly appreciated.
Thanks guys.

 

[mmi]

The differential lock comes on for 3 minutes when ignition is switched on.

Please clarify - it's only the light on dash only ignition switched on = engine not running??

after that & the light goes out I can switch it on & off without an issue with the dash switch.

Does the lock actually engage then?

 

[manfrotto]

This may give you a clue?

G

Thread 'Rear Diff Lock keeps switching on'

24 Dec 2025

My rear diff lock has started switching on without the button being pressed. Sometimes I cant even get it to disengage. I have done a battery reset but that made no difference. It can happen after cold or hot start.
Any advice please on what the cause it and how to rectify it

• gembleto
• Replies: 1
• Forum: Engine, Gearbox, Exhaust, Drivetrain

 

[Chris Brett]

Please clarify - it's only the light on dash only ignition switched on = engine not running??


Does the lock actually engage then?

Cheers for getting back to me, I switch the ignition on & start the engine the dash light comes on (on its own accord) & the diff lock engages for the 3 minutes then dash light goes out. All on its own.!!
Interestingly (MAYBE) whilst driving the van & the stop-start kicks in at juntions etc. the problem doesn't occur.??!! I guess this is because the ignition isn't swith off & a current is still present.

 

[manfrotto]

Always 3 minutes exactly each time?

 

[Chris Brett]

Yep

 

[mmi]

Cheers for getting back to me, I switch the ignition on & start the engine the dash light comes on (on its own accord) & the diff lock engages for the 3 minutes then dash light goes out. All on its own.!!

Fascinating

Anything different (with dash/button lights) if you remove fuse SC14 (diff lock control unit power).

What about having SC33 removed (but SC14 in place)?

 

[Chris Brett]

I give the fuse removal a go but can anyone confirm how many relays there are on the system ? I believe there one in the cab area & one on the diff itself.

 

[mmi]

how many relays there are on the system ? I believe there one in the cab area & one on the diff itself.

Relays... I would say only one aka "J187-Differential lock control unit"- under left seat - has label "509" on it. It's a bit more than just a relay.

On the diff-lock there is a "Control element" which contains the "sensors" (reed contacts) to monitor diff-lock status but not exactly relays.

7 - Control element

❑ On rear final drive​

❑ with:​

♦ Reed contact switch 1 for differential lock -F360-​

♦ Reed contact switch 2 for differential lock -F361-​

♦ Reed contact switch 3 for differential lock -F362-​

♦ Vacuum switch for rear differential lock -F363-​

Volkswagen Throttle Control Element 02W525641A - LLLParts

Volkswagen Throttle Control Element 02W525641A

www.lllparts.co.uk

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