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Pete
Pete, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 26255
Experience:  Over 15 years experience as a Mercedes dealer technician
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Ml430 in limp mode - but the low range light is on. only

Customer Question

ml430 in limp mode - but the low range light is on. only thing I did was fooling with fuses to attempt to fix the radio.
JA: Have you located the fuse box? Do you know the fuse number?
Customer: On the fuse number I just put them all back where they came from - I'd have to recheck . . .so it jumps into gear and revs up to 30k rpm
JA: What year is your ML430?
Customer: 2000
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: couldn't do anything yesterday. thought I'd look at it today - so I went on line hoping to avoid the costs at the German motors . . .
JA: Anything else you think the mechanic should know?
Customer: No . . . I have to do a little homework and testing - have some time today
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Mercedes Mechanic about your situation and then connect you two.
Submitted: 8 months ago.
Category: Mercedes
Expert:  Pete replied 8 months ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

In allot of cases this is either the transfer case low range shift actuator at fault or the transfer case shift computer located under the center console at fault.I have had to replace both for this fault here before.

Try this,start the engine and shift to neutral then try shifting in and out of low range with the low range button a few times and see if this resolves the fault.In some cases all it takes is cycling this button a few times to reset the system.

If this does not work then you will need to have the transfer case fault codes read out/checked with a scan tool that will plug into your model and reads your transfer case computer.Once this is done at least one code will be set that will help diagnose and locate the fault here.In most of the cases I have seen I have had to replace the transfer case shift motor on the transfer case itself for this issue.

If this only occurred after swapping fuses around you may just need to have the fault codes cleared out with a scan tool compatible with your model to reset the system.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 8 months ago.
I have tried the reset in neutral. The button/switch for low range came off a few years age. The button doesn't move or light up. I used the aux switch cover ... No luck. It won't downshift in drive either.
Expert:  Pete replied 8 months ago.

O.k.,these are all characteristics of the low range shift actuator on the transfer case itself at fault.I have had to replace this actuator before for this fault here several times on this model.It is held in place with 3 bolts and a wiring connection and usually takes less then a half hour to replace.The motor itself is usually $250 or less.

You will want to have the fault codes checked with a fully compatible scan tool to make sure that the motor/actuator is the cause needing replaced as in some cases the transfer case computer under the center console will need replaced.

Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.

Thanks Pete

Customer: replied 8 months ago.
This is no any more helpful than the free forums online .. I have to take it to someone that can look at the codes. I'm not in a position to work on this car.
Expert:  Pete replied 8 months ago.

Unfortunately without checking codes this can be difficult to diagnose due to the computerized controlled transfer case.If you have a test light or multi meter I can see if I can locate the info on testing the actuator signals as well as power and ground signals at the control unit/ecu if you would like just let me know.

Thanks Pete