Brakes losing power under 4x4 Low Gear.

[pjpvi]

For what it's worth, before a trip to the Maze District last year I replaced my vacuum pump and had brake system flushed. While I wouldn't call the brakes fantastic now, it did make a good improvement. Difference in hand spinning old vacuum pump to new was night and day. Old one was clearly worn. I had signs of reduced vacuum, so it was a pre-emptive maintenance move before it failed in the middle of nowhere.

Phil

[chetubi]

Originally Posted by chetubi

I have (partly) the Same problem. So I am bringing this thread to new life.

2008 e350 V8 gas. Quadvan 4x4.

When i switch to low gear and push the pedal ... Nothing happens. Does not rev up. Van just starts driving at about 1 mph. Just when I push the "TCS" button it drives normally. Strange enough. (Any thoughts about that?)

No problems there in 4x4 high!

But often when i am driving in low gear (Tcs button pushed) and need to brake I have symptoms like in this thread. Pedal low. Just hesitatingly braking. Feeling somehow like ABS.

Any ideas??

Here in germany not to much knowledge about e350 is acumulated.

Philipp

Someone else? Everything might help.

Tried again today. Braking is normal until the very end. To bring it to a full stop. Then it will act like ABS is working.

[BajaSportsmobile]

I am having difficulty understanding your statements/questions. Perhaps you are addressing two different issues - that maybe related.

Is the first issue that, when you push the accelerator pedal, when in 4WD Low Range, that the engine will not increase RPM's? Then, when you turn off the TCS system, engine RPM's increase and van accelerates normally in 4WD Low Range? Additionally, there are no issues when in 2WD or 4WD High Range?

The second issue is that the brakes, when in 4WD Low Range only, seem to actuate the ABS system and cause a low brake pedal.

Am I understanding you correctly?

A couple of questions:

When in 4WD Low Range and experiencing these issues, is it with the front hubs locked or unlocked?

When in 4WD Low Range, does the speedometer read the correct ground speed or does it read a much higher speed?

Originally Posted by chetubi

I have (partly) the Same problem. So I am bringing this thread to new life.

2008 e350 V8 gas. Quadvan 4x4.

When i switch to low gear and push the pedal (Accelerator?) ... Nothing happens. Does not rev up. Van just starts driving at about 1 mph. Just when I push the "TCS" button it drives normally. Strange enough. (Any thoughts about that?)

No problems there in 4x4 high!

But often when i am driving in low gear (Tcs button pushed) and need to brake I have symptoms like in this thread. Pedal low. Just hesitatingly braking. Feeling somehow like ABS.

Any ideas??

Here in germany not to much knowledge about e350 is acumulated.

Philipp

[chetubi]

I understanding you correctly?

A couple of questions:

When in 4WD Low Range and experiencing these issues, is it with the front hubs locked or unlocked?

When in 4WD Low Range, does the speedometer read the correct ground speed or does it read a much higher speed?



Quote:

Hello,

sorry for Not being so clear. Might be a language problem too.

But yes. You understood what I mean! And yes I meant the accelerator.

There are the two (!) problems which might be related.

Adressing your questions:

It is when the front hubs locked. But I am quite (Not 100%) sure it also happened when unlocked.

When in 4WD low range the speedometer shows a much higher speed. Not the normal speed.

Thanks for helping!!

Philipp

[BajaSportsmobile]

It sounds like the problem is with the RSC and or ABS system - perhaps getting the wrong speed signal in Low Range. One system thinks you are going 2.7 times faster than you are really going or vice versa.

Try disabling the ABS by pulling the large fuse under the hood, and see if this stops the systems.

[chetubi]

@Baja
Thank you!

Sounds convincing for me.

Do You know any easy fix if it is what you suppose? Anything I can tell a german mechanic not used to our vans?