1993 300GE 463 - Locking Diffs

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Noblebenn
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Hi All.

Just wondering if someone could help save me some time by possible pointing me in the right direction.

Never used the locking diffs as never had any need to. Just for fun thought I would try them out but none of the buttons seem to be engaging and none of the lights are illuminating. 

First place to start looking ......?

Thanks

 

Pistonhead
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Re: 1993 300GE 463 - Locking Diffs

Hello Benn

​Assuming that is your name. For future reference please indicate your model .

Assuming you have the W460 chassis, this is the one with the diff. lock levers by the centre consol. 

The front pull up lever is to operates and engage or disengage the front locking diff. and it follows the rear one is for the rear locking diff.  To engage the locking diff, one simply pulls up the wanted lever and initially an amber light will illuminate on the dash panel showing two axle icons. This remains amber to indicate the lock has been selected. It should turn red once the lock diff physically engages. The two icons are one over the other whereby the top indicates front axle and the bottom is indicating rear diff operation.

Selection can be done at walking pace, if this does not allow then one must stop to make the procedure. 

Selection of the diff locks has a precedence although you can over ride this. The engagement is done by select as and when you require the rear diff lock first and then the fronts. DO not operate the fronts for prolonged turning as you will find out the steering becomes heavier and having a tendency to straighten up. Operate the diff locks only on loose surface or muddy situations. If not done so can create transmission wind up and in extreme situations serious damage could result. The vehicle seemingly seems to loose power; in such conditions back track your drive to unwind the built up stress.

BEFORE coming to use the diff locks you should have gone through engaging four wheel drive, using High gear and Low gear of the transfer box and if these do not help in traction then is the time to start using lock diffs. These are there merely to lock a slipping wheel to regain traction and get you out of trouble. 

To operate the four wheel drive; using the transfer box lever (extra gear lever in front of or by side of normal gear lever)  moving this lever forward engages four wheel drive mode in High ratio. To select Low ratio slide the gear to the right in the same plain and then move it backwards as though you would selecting 2nd gear. The first notch puts the vehicle in neutral (this is a function using power take offs, so even if the vehicle is in normal engaged gear mode you will have NO drive in this position) pull the gear lever further will select the gear lever in the next and final notch or position. This engages Low ratio in four wheel drive. 

If you have the  W463, this has electrically operating buttons to engage locking diff's. This model is constantly four wheel drive and the buttons are mounted centrally on the dash panel. There are three switches and is sequentially operated and are mounted one above each other. The top switch operate the front diff the bottom operates the rear diff and the centre one operates the centre diff lock. The sequence is to engage the centre switch firstly, then the bottom secondly and top finally. The sequence cannot be overridden. Once these are engaged they may be all canceled by switching off the centre diff. Again these may be selected at walking pace. The transmission wind up behaves the same as described above. 

In either case do not engage these on hard surfaces, only loose surface.  

JASONGDS
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Re: 1993 300GE 463 - Locking Diffs

Assuming you are pressing the middle switch first.? Still no lights? Check relays behind fuses, there is timer lag relay , and 3 others that control each differential lock. Hopefully someone will post a picture of the relays, then one can advise how to swap the relays, worst case scenario is the switch has failed,  as it' s expensive. 

Is this the 1st time you have tried them.. ?

Central diff lock essential in snow, or stuff that stops normal cars

Noblebenn
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Re: 1993 300GE 463 - Locking Diffs

Thank you for the replies. 

Model is a 1993, 300GE 463 as in the title. 

Yes I tried them in order but the lights aren’t switching on. I shall check the relays this weekend and hopefully all will be well.  

I’ve used the high and low gear box which works well but yeah, never the locking doffs  only ever used the car on road so far.

Thanks

 

 

 

 

JASONGDS
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Re: 1993 300GE 463 - Locking Diffs

Does your rev counter work? That shares the same fuse as the diff lock

Arnie
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Re: 1993 300GE 463 - Locking Diffs

Please check your PM for details on diff locks and wiring etc.

The diff locks rely on electric solenoid valves that operate a vacuum system that drives the hydraulic actuators through pressure amplifiers. The operating logic is controlled by a special relay. If you have a pneumatic or hydraulic failure you would still see the orange standby lights, if not the red engaged lights. If you have no lights at all, it's probably an electrical issue:. As soon as you press the centre diff-lock button, the ABS system should be disabled with a yellow warning light in the binnacle. If your diff buttons are completely dead, it points to an electrical problem.

Noblebenn
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Re: 1993 300GE 463 - Locking Diffs

Yes the rev counter works fine.

Arnie, thanks so much for the attachement, that will be a huge help. Looks like it could be an electrical gremlin.

Will update once sorted.

 

JASONGDS
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Re: 1993 300GE 463 - Locking Diffs

Does everything else work fine.? All the switches work on the central panel ?