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  #1  
Old 11-11-2002, 08:14 PM
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Join Date: Mar 2001
Location: Southern California
Posts: 373
The Mel died again...

I posted on this awhile back....something drains the battery in the ML and it's dead when I go to start it. This time I left the car parked for 8days. So it's something that is not found when the car is driven often; i.e. charging system is working..... I caught the coolant recirc pump running longer than the 10mins it's supposed to run so we blamed it for running until the battery was dead. The pump, the switch and the battery were replaced.

Since I took it back in several times for the same problem, when it stopped happening, we thought the battery must have been sulfanated and weakened. (They just replaced the CLK battery for me under warranty, maybe there was a bad batch of batteries in 2000.... 24months is certainly premature wear in So. Cal! ) Well, the only thing that remains in the coolant pump circuit is the ECU. That's expensive but the only thing left that could be causing the coolant pump to run on... this problem is so weird and not obvious in it's cause...anyone else left their car for several days and found the battery dead?

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Ed "Don't Benz's just feel better..."

Current wives...
2000 ML430 Skyview "The Mel"
2000 CLK430 Cab "The Cab"
85 300D Turbo "The Diesel"

Past wives...
92 300E
85 190E

"One should as a rule respect public opinion in so far as is necessary to
avoid starvation and to keep out of prison, but anything that goes beyond
this is voluntary submission to an unnecessary tyranny, and is likely to
interfere with happiness in all kinds of ways."
Bertrand Russell
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Old 11-11-2002, 11:27 PM
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Join Date: Sep 2002
Location: Missouri
Posts: 80
I suggest measuring the current draw from the battery when the truck is not running and then start from there. I don’t think the 10 minutes run for the aux. coolant pump would do battery that bad (it is designed to run for around 30 minutes in residual heat mode). But frankly speaking, I don’t remember my aux. Coolant pump ever run more than maybe 5 minutes after I stopped the truck.

What is the sensor that controls that pump, anyone know?

ps.
I've left the truck along for more tahn 10 days several times, no problem starting waht so ever.
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  #3  
Old 11-12-2002, 12:40 AM
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Location: Evansville WI
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The control unit involved is the AAM (all-activity module).
I believe I have heard of this malfunctioning in this manner before.
The early ML's have no REST functon, it got this function in model year 2002 when the climate control was revised. In all MB's I am aware of, the REST function will operate until the voltage has been drawn down to 11 volts, or if the system is unable to provide cooling or heating as required to maintain the set temp, in other words the heater core has cooled off or the evaporator has warmed up too much.

Gilly
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Old 11-13-2002, 06:35 PM
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Join Date: Mar 2001
Location: Southern California
Posts: 373
Sorry about my earlier misstatement, it's the AAM that's left to change out, or so I was told....

There is a switch in the circuitry that helps with temp. sense that helps the AAM decide whether to turn on the aux. pump.

Gilly, the REST function sounds like what the factory designed to correct my problem. Can that be retrofited on my MY2000?
__________________
Ed "Don't Benz's just feel better..."

Current wives...
2000 ML430 Skyview "The Mel"
2000 CLK430 Cab "The Cab"
85 300D Turbo "The Diesel"

Past wives...
92 300E
85 190E

"One should as a rule respect public opinion in so far as is necessary to
avoid starvation and to keep out of prison, but anything that goes beyond
this is voluntary submission to an unnecessary tyranny, and is likely to
interfere with happiness in all kinds of ways."
Bertrand Russell
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  #5  
Old 11-13-2002, 11:43 PM
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Join Date: Mar 2001
Location: Evansville WI
Posts: 9,616
Mmmm, no it can't be retorfitted into yours, but it wouldn't really have anything to do with your problem. REST function is for like if you park the truck and are going to run in to a store for a short time. You can hit the REST button and it will run the climate control at a very slow fan speed to try to keep the interior cool or warm, as the weather dictates. It's really a comfort system, nothing to do with this aux motor running to prevent hot-spotting.
There is NOT a temp related function to help the truck decide to run the aux pump to prevent hot spotting. If you take a stone-cold engine, turn the key to ON (not even starting the engine) and turn the key off, the aux pump will run for the programmed amount of time, then shut off. I don't think it runs for over 5 minutes, not sure on the time factor, but it isn't temperature dependent. The small blower motor in the bottom of the control module box operates in conjunction with the aux coolant pump.
In short, the function is controlled by a timer in the AAM.

Gilly

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