Diff Locks
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Joined: Aug 2017
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G270CDI
Diff Locks
Hi all,
My G is having some weird behavior while engaging diff locks. It is a diesel W463 270CDI from 2005.
The central diff lock engages within a second, the rear sometimes engages and others take a while to engage and the front one has the same behavior as the rear one.
I've already measured the vacuum and does not have any leaks.
I've tested the diff locks with the G on a lift.
I've also measured the signal to the solenoids and it is sometimes intermitent to the rear and front diff locks. Sometimes the signal is stable but others is switching on and off very fast.
What other tests can I do to it?
How can I get the electrical wiring drawing for the diff locks? Can this be a relay issue on the comand sent to the solenoids?
What components usually fail on the diff locks either electrical or mechanical?
Where is the control module located?
Thanks in advance.
Rodrigo
My G is having some weird behavior while engaging diff locks. It is a diesel W463 270CDI from 2005.
The central diff lock engages within a second, the rear sometimes engages and others take a while to engage and the front one has the same behavior as the rear one.
I've already measured the vacuum and does not have any leaks.
I've tested the diff locks with the G on a lift.
I've also measured the signal to the solenoids and it is sometimes intermitent to the rear and front diff locks. Sometimes the signal is stable but others is switching on and off very fast.
What other tests can I do to it?
How can I get the electrical wiring drawing for the diff locks? Can this be a relay issue on the comand sent to the solenoids?
What components usually fail on the diff locks either electrical or mechanical?
Where is the control module located?
Thanks in advance.
Rodrigo
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Newbie
Joined: Aug 2017
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G270CDI
Hi Dutch,
I am not sure when it was bleeded. I believe it should be bleeded every 3 years right?
The issue i believe it is not the hydraulic part but the electric part.
The tests i have made, with the G lifted, the diff locks actually lock when the button is pressed.
The central lock almost imediately, the rear and front lock sometimes lock almos imediately and others dont. With a voltmeter i have measured the signal to the solenoids that control the vacuum and for the central diff lock, the signal is "steady", for the rear and front diffs the signal is most of the times "ON" and "OFF" and when the signal is "ON" the diff actually locks and the red light on the dashboard is also on.
I hope that i have explained it clear.
Thanks in advance,
Rodrigo Catarino
I am not sure when it was bleeded. I believe it should be bleeded every 3 years right?
The issue i believe it is not the hydraulic part but the electric part.
The tests i have made, with the G lifted, the diff locks actually lock when the button is pressed.
The central lock almost imediately, the rear and front lock sometimes lock almos imediately and others dont. With a voltmeter i have measured the signal to the solenoids that control the vacuum and for the central diff lock, the signal is "steady", for the rear and front diffs the signal is most of the times "ON" and "OFF" and when the signal is "ON" the diff actually locks and the red light on the dashboard is also on.
I hope that i have explained it clear.
Thanks in advance,
Rodrigo Catarino
MBWorld Fanatic!
Joined: Aug 2002
Posts: 1,308
Likes: 35
From: Atlanta, GA USA
2000 MB G500 NMLE, 2015 Audi Q7 3.0 TDI Prestige
If you don't know when the diff locks were last bled, I would start there. The center is purely vacuum operated, so there's no bleed procedure there. Do bleed the rear and front with DOT 4 Brake Fluid.
Then recheck the operation. The fronts and rears are very rarely an immediate lock. The gears have to rotate to get lined up before the lock can slide into place.
Then recheck the operation. The fronts and rears are very rarely an immediate lock. The gears have to rotate to get lined up before the lock can slide into place.
Thread Starter
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G270CDI
If you don't know when the diff locks were last bled, I would start there. The center is purely vacuum operated, so there's no bleed procedure there. Do bleed the rear and front with DOT 4 Brake Fluid.
Then recheck the operation. The fronts and rears are very rarely an immediate lock. The gears have to rotate to get lined up before the lock can slide into place.
Then recheck the operation. The fronts and rears are very rarely an immediate lock. The gears have to rotate to get lined up before the lock can slide into place.
I understand your point, and i will bleed the rear and front diff locks. Do you know how many liters of brake fluid is needed?
Where can i find the procedure to bleed the diff locks?
I know that they dont lock immediately, when i had the G on the lift i had to put some resistance on one wheel in order to be able to lock.
But my point is that the electrical signal that goes in to the solenoid, it is not permanent when i push the button on the dash.
When i push the button the signal should be permanent 12v on the solenoids and on the rear and front it is not. When the signal is stable the diff actually locks.
Do you know where can i find the electrical schematics of the diff locks command and components?
I believe that there is a sensor that sees if the diff is actually lock, right? Could this sensor be faulty?
Do you think that if i disassemble the actuator on the diff that i will be able to see if it moves?
Thanks again for your help.
Kind regards,
Rodrigo Catarino
MBWorld Fanatic!
Joined: Aug 2002
Posts: 1,308
Likes: 35
From: Atlanta, GA USA
2000 MB G500 NMLE, 2015 Audi Q7 3.0 TDI Prestige
Hi Dutch,
I believe that there is a sensor that sees if the diff is actually lock, right? Could this sensor be faulty?
Do you think that if i disassemble the actuator on the diff that i will be able to see if it moves?
Thanks again for your help.
Kind regards,
Rodrigo Catarino
I believe that there is a sensor that sees if the diff is actually lock, right? Could this sensor be faulty?
Do you think that if i disassemble the actuator on the diff that i will be able to see if it moves?
Thanks again for your help.
Kind regards,
Rodrigo Catarino
Do NOT disassemble the solenoid, or you might have trouble getting it properly reinstalled.
BLEED THE DIFF LOCKS before doing anything else!!
As a trouble shooter, there is an old adage that fits perfectly here. "When you hear the sound of hoof beats, look for horses - NOT zebras!"
Last edited by DUTCH; Aug 31, 2017 at 08:57 AM.
Thread Starter
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G270CDI
There is a sensor in the solenoid on the axle, The reason I want you to bleed your diff locks first is that air in the lines will prevent the sensor for showing that the diff is locked; and this could be the root cause of your problems.
Do NOT disassemble the solenoid, or you might have trouble getting it properly reinstalled.
BLEED THE DIFF LOCKS before doing anything else!!
As a trouble shooter, there is an old adage that fits perfectly here. "When you hear the sound of hoof beats, look for horses - NOT zebras!"
Do NOT disassemble the solenoid, or you might have trouble getting it properly reinstalled.
BLEED THE DIFF LOCKS before doing anything else!!
As a trouble shooter, there is an old adage that fits perfectly here. "When you hear the sound of hoof beats, look for horses - NOT zebras!"
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Member
Joined: Dec 2010
Posts: 138
Likes: 30
From: Houston, TX
Lifted G500, GT-S, track Cooper S
FWIW, my diffs had not been used much by the previous owner (Doctor) and so when I got it, were not easy to get to lock up even with axle slippage trying to engage them.
I had the fluid replaced and a good bleed job, and got a marked improvement. They still need exercising every so often but it definitely helped.
I had the fluid replaced and a good bleed job, and got a marked improvement. They still need exercising every so often but it definitely helped.
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G55
Not sure if this is the correct thread to ask this, but I recently purchased a 2005 G55 and while driving the Red light came on by itself and got the message Differential Locked. I did not touch the switches any suggestions on how to diagnosis the issue? Hate to go to the dealer and pay a minimum 180 fee regardless of the repair cost. Thank you
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