Hi all, l have a problem with one of the diff locks. l pressed the buttons in for both diff locks and only one seems to be working and displaying 1 of the diff icons on the screen. you can hear the air getting to both when the buttons go in though. l thought l would swap the buttons incase it was faulty but no joy. lt does seem to be an electrical fault… Anyone have any suggestions please?
I assume double drive? pop under the chassis nearside inner chassis rail over the first drive axle you will see two small valves called mag valves 3 maybe 4 pipes and two plugs, swap the plugs over and if the dead switch now makes the other mag valve work you have a dead valve, if it doesnt you have a wiring fault.
One mag does the cross lock in the front axle case and the other mag does both diff locks in both axles at the same time.
If you have to change one of the mags dont lose the o-ring that sits between them, easily done and its a square shape jobby so your universal kit of o-rings wont work.
Have you jacked it up to check before you go searching for electrical faults ?
Trickydick:
I assume double drive? pop under the chassis nearside inner chassis rail over the first drive axle you will see two small valves called mag valves 3 maybe 4 pipes and two plugs, swap the plugs over and if the dead switch now makes the other mag valve work you have a dead valve, if it doesnt you have a wiring fault.
One mag does the cross lock in the front axle case and the other mag does both diff locks in both axles at the same time.
If you have to change one of the mags dont lose the o-ring that sits between them, easily done and its a square shape jobby so your universal kit of o-rings wont work.
Thx Trickydick, l will give it ago tmrw. Yes your right its double drive.
Punchy Dan:
Have you jacked it up to check before you go searching for electrical faults ?
Hi Punchy Dan, no l havent. l took it to get the tacho recalibrated and the guy had it on the rolling ramp. But because it wouldnt go into diff he couldnt do the recalibration. Anyway he got underneath and tried afew things and said it seems to be an electrical problem and said to fix it then bring it back. The air seems to be there as you can hear it when you put the button in…
Firstly I would do as Dan says and jack it up to see what axle is at fault ,and wether it is the diff locks or the cross lock that may / may not be faulty …Secondly if my mind serves me right DAF only have the 1 warning light on the CF 75 ,So possibly nothing is wrong and the tacho lad was expecting more lights… Been working on them for over 20 years and strangely the amount of warning lights eludes me ,I’m sure it’s only 1 …If you even have your handbook it will tell you in there how many there are …If you give me your chassis number I can try and find out
norb:
Firstly I would do as Dan says and jack it up to see what axle is at fault ,and wether it is the diff locks or the cross lock that may / may not be faulty …Secondly if my mind serves me right DAF only have the 1 warning light on the CF 75 ,So possibly nothing is wrong and the tacho lad was expecting more lights… Been working on them for over 20 years and strangely the amount of warning lights eludes me ,I’m sure it’s only 1 …If you even have your handbook it will tell you in there how many there are …If you give me your chassis number I can try and find out
Thx norb, l sent you a pm
norb:
Firstly I would do as Dan says and jack it up to see what axle is at fault ,and wether it is the diff locks or the cross lock that may / may not be faulty …Secondly if my mind serves me right DAF only have the 1 warning light on the CF 75 ,So possibly nothing is wrong and the tacho lad was expecting more lights… Been working on them for over 20 years and strangely the amount of warning lights eludes me ,I’m sure it’s only 1 …If you even have your handbook it will tell you in there how many there are …If you give me your chassis number I can try and find out
norb if it turns out to only have 1 icon on the dash for the diff, then no matter which diff button l push in 1st should the diff icon show up or does it only show up on 1 of the buttons…?
Thx again
To be honest you would always engage the diff locks first ,then the cross lock ,but I think both will activate the light …To be honest it’s not something I have paid much attention to 
its an age thing
The inter axle diff lock, (also sometimes known as the third diff lock)has to be working in order for the tacho to be calibrated. The cross locks are not important for this.
The easiest way to check if it is engaging is to jack up any one of the four rear wheels. Then,engage the lock and with the engine running and the brakes off engage a gear, release the clutch gently and if the lock is in the vehicle will drive off the jack.
If it is not engaging, the wheel which is off the ground will just rotate freely.
You say you can hear the air going in, if you press the buttons one at a time to release the locks, can you hear two sounds of the air being exhausted?
All fixed thx to you guys and your advice… Thank you all.
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