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1998 ML320, 2000 ML320
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213 Posts
Discussion Starter #1 (Edited)
2000 ml 320, 130,000 miles, has been running perfect without any problems. I recently noticed the battery seemed weak and the starter seemed a little slower than normal. I checked each battery cell and added appropriate amount of distilled water and trickle charged the battery. My black and decker charger said battery was good. Everything seemed ok for a few days.

I then get a call from my wife and the car will turn over for several seconds but wont start. Called MB mechanic friend and he said check the fuel pump fuse. It was ok but I put in a new one and jiggled the fuel pump relay. Then it started. I turned it off and gave my wife my ML and she left. When I went to start her ML again it had the same problem of turning over but no start. I looked at the relays in the fuse box and several looked the same so I asked my MB friend if I could swap one for another to try and get the car going. He said if they look the same you can swap them. I swapped the fuel pump relay for the horn relay and the car started and worked fine for a few days. Then one morning I went out and the battery was basically dead and car would not even turn over. I figured the battery was shot since it was the original and 8 yrs. old. I get a new battery and install it and car is back to normal for a week and a half or so. Then my wife was in a parking lot at idle and the car just quits. Then it turns over but wont start again. When I get there I put the horn relay back in the horn slot and the fuel pump relay back in the fuel pump slot and car fires up fine and I drove it home and restarted it a few more times and it seems to be working fine. The problem is it has never done this before and I don't feel I can trust it to be reliable for my wife right now. Any ideas and thanks.
 

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2014 RX 350 F Sport, 2007 Scion tC, 2000 ML 430 Money Pit Finally Gone! Oh Happy Day!
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1,284 Posts
2000 ml 320, 130,000 miles, has been running perfect without any problems. I recently noticed the battery seemed weak and the starter seemed a little slower than normal. I checked each battery cell and added appropriate amount of distilled water and trickle charged the battery. My black and decker charger said battery was good. Everything seemed ok for a few days.

I then get a call from my wife and the car will turn over for several seconds but wont start. Called MB mechanic friend and he said check the fuel pump fuse. It was ok but I put in a new one and jiggled the fuel pump relay. Then it started. I turned it off and gave my wife my ML and she left. When I went to start her ML again it had the same problem of turning over but no start. I looked at the relays in the fuse box and several looked the same so I asked my MB friend if I could swap one for another to try and get the car going. He said if they look the same you can swap them. I swapped the fuel pump relay for the horn relay and the car started and worked fine for a few days. Then one morning I went out and the battery was basically dead and car would not even turn over. I figured the battery was shot since it was the original and 8 yrs. old. I get a new battery and install it and car is back to normal for a week and a half or so. Then my wife was in a parking lot at idle and the car just quits. Then it turns over but wont start again. When I get there I put the horn relay back in the horn slot and the fuel pump relay back in the fuel pump slot and car fires up fine and I drove it home and restarted it a few more times and it seems to be working fine. The problem is it has never done this before and I don't feel I can trust it to be reliable for my wife right now. Any ideas and thanks.
Sounds like a failing CPS (crank position sensor). Common problem that leaves a code, but no light on dash. My 2 cents. :thumbsup:
 

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'07 C280 4matic, '06 530i, '98 ML320
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1,562 Posts
it's interesting that every time fuel pump replay is swapped (or tweaked around), the truck starts.

To validate the diagnosis the CPS is bad, next time when the truck doesn't start, look at the tachometer (while trying to start). If the tachometer doesn't show any reading, then the CPS is bad.
 

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02 ML320 06 ML500
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17,037 Posts
Sounds like a failing CPS (crank position sensor). Common problem that leaves not code. My 2 cents. :thumbsup:
Azinn, there is a fallacy of the CPS not storing a code. It will. The only function of the check engine light is to alert the driver of a problem with the emissions system which might impact the environment. Members on this forum have been wrongly conditioned to believe that if the CEL does not illuminate, there are no codes stored. This is not true in the least, and because of this belief people do not use a scanner or code reader to help direct them to the right area. There are many driveability codes (including MAF sensor ones) that will be stored, but I guess someone on this forum way back when, stated that the CPS will not throw a code and it has carried down from there.
 

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1998 ML320, 2000 ML320
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213 Posts
Discussion Starter #5
Drove the truck to work today and it died while driving. I was able to coast into a parking lot. I tried to restart it and it turned over but would not start. While looking at the tach needle on the starting attempts I noticed it did not budge. I swapped relays around again and it restarted. It made it the rest of the way to work okay. I sent wife to buy CPS today and plan to install it tommorrow night. The truck drove home today without incident. Once I install the CPS I will post results. Thanks for your help.
 

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My '98 ml320 vibrates and engine goes off while in motion. After several attempts, it would start and go off after driving a short distance. It happens frequently, infact, sometimes it would refuse starting, but if tried after some hours have elapsed, the engine would start again. I also noticed sometimes, the rev-meter needle drops to the lowest point and rises again while the SUV is in motion. Please what may be the problem?
 

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It was fun while it lasted
2002 ML320, 2005 S430 4MATIC RIP, 2010 F150 Crew Cab
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11,146 Posts
I'm a little confused here. It has been said numerous times that the tachometer needle is supposed to move when the vehicle is trying to start. But, the needle doesn't budge on either of my ML's until it starts. I'm having no starting issues with either. :confused:
 

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02 ML320 06 ML500
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17,037 Posts
I'm a little confused here. It has been said numerous times that the tachometer needle is supposed to move when the vehicle is trying to start. But, the needle doesn't budge on either of my ML's until it starts. I'm having no starting issues with either. :confused:
Mitch, this only relates to CRANK-NO START. On a sustained crank it will register slightly to approx 200 RPM's.
 

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99 ML430 - 13 328i
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1,112 Posts
My car would not start sometimes, it was cause of the CPS. all guages worked good, batt good, starter good. you could crank the crap out of it and it wouldn't start till a few hrs later or something.
 

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1998 ML320, 2000 ML320
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213 Posts
Discussion Starter #10
Put in the CPS today and will be driving to see if reliability is back. The location of the CPS is nothing short of ridiculous. I did however come up with a help tip that I don't remember reading in the DIY section. I popped my gas struts loose from the hood connection and reconnected them to the two ball joints that allow the hood to be held open much higher. Makes job easier but still a completely stupid procedure. I might guess that the biggest help would be to move the throttle unit out of the way if possible. It looks like it has two nuts holding it up top but not sure how its lower mount functions. Thanks again to all that have responded on this and I will let you know how things go from here.
 

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1998 ML320, 2000 ML320
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213 Posts
Discussion Starter #12
Been driving the truck for almost a week now without any starting or dying problems after installing CPS. It seems to have done the trick
 
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