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Mercedes ML320 Intermittance power issues

9K views 55 replies 10 participants last post by  vvrjrlaw 
#1 ·
Please help. About 2 weeks back we started to experienced issues with our ML320 mercedes. We will drive and the radio as well as dashboard instruments will shut down (all indicators will move back to "zero" position) No lights will flash or come on. The car does not loose any power on the engin and we continue to drive. As sudden as this happens, it will immediately correct itself and radio will starts playing again and all dashboard instruments will display as it should. Then on other times, the above will happen but now all lights on the dash will come on and the car will loose power totally on the engin. If your foot is on the petrol, this will rectify itself within 2-3 seconds and the engin will kick in exactly where it "stopped" previously with all dash instruments displaying correct info. If your foot however is not on the petrol, the car has stalled 2x now and we can only start within about 2 minutes thereafter. The above will not happen if we pull out the car in the morning and drive to work. This will only starts happening after the 2nd or 3rd drive around town (same day). Since the symptoms started we have replaced the crank shaft sensor (bought new one) and we also replaced it again (to see if initial new one was not faulty). No change in symptoms. We took it to a garage twice for them to put the diagnostics tools on but no error is picked up. We dont know what more can cause this type of problems but at this stage the car can switch off anytime anywhere which is a risk. If anyone has advice please share.
 
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#4 ·
The only commonality the Radio and Instrument Cluster share are two GROUND points, W16/4 and W29/2.

Remove the nut that affixes the GROUND cables, clean the ends and reinstall them with the same configuration as before.

Warning: before removal, make sure you have your radio code.
 

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#5 ·
Mercedes ML320 Intermittance power issues Reply to Thread

What usually happens in the 2 minutes (lights on dash came on - all of them, engin looses power and then finally stalls - so lights go off as well). I will put the gear in park(automatic gearbox) and retry to switch the car on - lights on dash will liught up as normal. The starter does crank the engin but even if you place your foot on the engin, the engin will run for a few seconds and then stalls again. I repeated this action about 2 times and then left it - waited for about 2 minutes, restarted the car and then the engin kept running and I could drive off. Hope this info helps.
 
#6 ·
What usually happens in the 2 minutes (lights on dash came on - all of them, engin looses power and then finally stalls - so lights go off as well). I will put the gear in park(automatic gearbox) and retry to switch the car on - lights on dash will liught up as normal. The starter does crank the engin but even if you place your foot on the engin, the engin will run for a few seconds and then stalls again. I repeated this action about 2 times and then left it - waited for about 2 minutes, restarted the car and then the engin kept running and I could drive off. Hope this info helps.
Scanner needs to be connected and entire vehicle scanned (all modules) after that unsuccessful start attempt. Take it to the shop, leave it and let them reproduce the problem. At this point vehicle cannot be trusted for more then flower pot or outdoor storage space.:frown

Or equip yourself with accurate volt meter, test light and basic OBDII scanner and tackle the problem.
 
#10 · (Edited by Moderator)
Last week while I was out of town my wife came out from a one hour dental appointment to find her 1999 ML320 (77,000 miles) would not start. She got a ride home and got a rental car, being afraid to drive my old SL500. [Cranked well twice, no engine run]

She picked me up at the airport and I suggested we spend 5 minutes looking at the ML320 on the way home. I got in and after 1-2 seconds it started fine and I drove it home. Today we were to meet at Enterprise to return the rental. I made a parking lot turn which put the car pretty nose down. It died and would not start so I decided to call a tow truck. Five minutes later it started and I met her at Enterprise. We checked in the rental and I stopped in front for her to get in, again on a slight down slope. NO START. I was able to coast down to a somewhat level spot but no start. The car was towed home and put in front of the garage.

After she went in I STARTED THE CAR AND PUT IT IN THE GARAGE. Then, again great cranking but no run! I used a simple scanner and will have to report the codes tomorrow, now on a paper in the garage, now forbidden to me for the night. NO CEL at any time. The car has been idling slightly rough for a while but drives fine when it runs.

I would guess that if I were allowed in the garage I suspect it would start.

Cranks just fine but behaves as if no ignition or no fuel. So sorry I can't report the codes which . . . strangely, will not clear with my scanner which always cleared codes on the '99 ML320 and my '98 SL500.

The ML was to go into the dealer soon to resolve a slightly rough idle but that's not going to happen soon.

I sort of think maybe a loose fuse or some such thing.

I'll post the codes tomorrow, I think a fuel unbalance (sort of standard with that car) and a transmission request and an engine speed sensor request, but no CEL.

I sort of doubt that cool-down time is an issue, it just dies nose down or won't start after just 5 minutes.

Looking through the other posts I need to say no basic electrical problem. Cranks fast and all lights work. Didn't have a chance to open the fuse box yet.

Here are the codes. NO CEL and couldn't clear them. That's when I found the engine wouldn't start after I drove it into the garage. When the codes wouldn't clear I tried to start the engine but it wouldn't start.

The persistent codes are:

P0720 Output Speed Sensor Circuit
P0700 Transmission Control System (MIL Request.
P0150 02 Circuit Bank 2 Sensor 1

Signed-
Stranded in Moore, Oklahoma
 
#11 · (Edited by Moderator)
I hope someone can give me some suggestions before the '99 ML320 has to go to the dealer for something over $500 plus parts and labor for the parts at full dealer price. The codes posted previously include a transmission request.

The replacement transmission adapter plug has been changed, by the dealer, and they didn't report any oil wicking. I also had a look at the TCM and didn't find any oil there.

Since the problem seems to magically repair itself from to time it just has to be something intermittent. I have yet to open the fuse box but will when I recover from my trip to find the wife with the sick car. The codes I found are in the prior post and I wonder whether my inability to clear them is a clue.

[My basic scanner has always been able to clear codes on this car and the '98 SL500 so I'm pretty sure it works. It simply reports that it was unable to clear the codes in this car at this time.]

===================

Re my '99 ML320 post.

Looking through the other posts in this thread I need to say no basic electrical problem. Cranks fast and all lights work. Didn't have a chance to open the fuse box yet.
 
#12 ·
Failure to start EGR?

One more clue. The 1999 ML320 seems to start and run well when cold!

Possible EGR valve problem? It's been idling a bit rough for several months and failed to start after sitting outside for an hour in the hot sun. (Dental visit). She got a ride home and rented a car. (Doesn't trust my '99 SL500 which is a bit questionable at times.)

When I got back here after dark it started well and I drove it home. I drove it to meet her at the rental car return but after we got the rental checked in the ML wouldn't start. Had it towed in and placed in the driveway. A few minutes later it started and I put it in the garage. Then wouldn't start. Now, a day and night later, it started twice in the garage.

I guess that tomorrow I'll try to see if I am able to clean the EGR system. I think I can see the valve but am not sure whether it is vacuum or electronic.

[My SL has always had a hesitation every 15 seconds during in-gear idle. Had that problem when I got it at 70,000 miles and no shop has been able to find the problem... EGR issue?]
 
#14 · (Edited)
One more clue. The 1999 ML320 seems to start and run well when cold!

Possible EGR valve problem? It's been idling a bit rough for several months and failed to start after sitting outside for an hour in the hot sun. (Dental visit). She got a ride home and rented a car. (Doesn't trust my '99 SL500 which is a bit questionable at times.)

When I got back here after dark it started well and I drove it home. I drove it to meet her at the rental car return but after we got the rental checked in the ML wouldn't start. Had it towed in and placed in the driveway. A few minutes later it started and I put it in the garage. Then wouldn't start. Now, a day and night later, it started twice in the garage.

I guess that tomorrow I'll try to see if I am able to clean the EGR system. I think I can see the valve but am not sure whether it is vacuum or electronic.

[My SL has always had a hesitation every 15 seconds during in-gear idle. Had that problem when I got it at 70,000 miles and no shop has been able to find the problem... EGR issue?]
You need to scan it right after failure to start. Better yet if your scanner shows life data look at engine speed while cranking. You have symptoms of dying crankshaft position sensor or dying fuel pump. Before putting your wife back in the car you need to diagnose it. Do not blindly replace parts.

Forget EGR. At least for now.
 
#17 ·
Replacement



Thanks. I can see the item but am not sure whether it has one or two wire bundles attached to it. There seems to be a flat plate extension as part of it and the pictures on line at various vendors don't show that.

Also, it turns out that for the 6 cyl 1999 ML320 there are two types of sensors and I can't tell which version I have. It depends on engine SN according to AutohausAZ. I found a paper tag lying on the header that has a batch of numbers on it but none seem to relate to the demarcation S/N they say the part is before or after the engine number.
 
#18 ·
It turns out the engine S/N will be hard to see. I will have a look later day and see if I can find it and then order the correct part. It's hidden behind the bulk of the intake system it seems.

I did find a faded paper label which had just come loose from the intake manifold but it doesn't have any numbers that seem to relate to the engine S/N.
 
#20 ·
VIN



1999 ML320

4JGAB54EOXA144794

I assume "O" is a letter O. :smile

One thing, no P0016 or P0017 codes which I understand relate to the sensor but the symptoms seem to match the descriptions of the problem.

Codes are, on my simple scanner
P0720
P0700
P0150

I have the necessary tools so just have to order the right sensor. I haven't been able to magnetize the Torx so will use tape to not lose the bolt into infinity.

Since I really can't see down there I'll have to disconnect by feel.:confused:
 
#22 ·
On order from Amazon. $1.15 with free shipping after some reward points I didn't know I had.

The various sites all have their own number so I entered the number from the picture and Amazon popped up.

I hope A 003 153 28 28 is correct for my car. I still don't know my engine number but relied on the posted diagram for the MB part number.

Thanks . . . .
 
#27 ·
Crankshaft position sensor replacement



I have to admit a little bit of all, no precisely related codes, no scope. Just my $30 scanner from Japan which has done wonders on the ML and my SL500.

The final trigger was when I got several recommendations about that item and also had to try to decide what would prevent the car from starting when warm . . . sort of a standard Hall-effect issue, based on my physics background.

What else? - fuel pump, a computer component, what? None of those get hot during a 10-15 minute run. It is true that the first failure to start happened when my wife came out from a dental appointment and the car had been sitting in the sun, normally it sits in the garage. When she picked me up at the airport after dark I asked to drop by and spend 5 minutes with it. It started instantly and I drive it home and she drove her rental. (She won't drive the SL.) The next failure to start was when I met her at the rental place the next morning and stopped the car while we turned in her rental. Five mile drive, 10 minute wait, call the tow truck . . .

I posted some codes that are in various ways somewhat related to that sensor. There were other symptoms not reported, in particular a backfire followed by a loss of power when my wife wanted to get away from a tailgater.

Slightly rough idle, not fixed by a series of MAF sensors. [Yes, I bought some cheap ones first. Then bought a factory model.]

There have been, over the past couple of years, some transmission codes which went away.

Gut feeling, yes, a bit.

Finally just the low cost to try this fix. A few bucks compared to towing the car (maybe it would drive all the way there) and pay $500 to walk in the door. Been there, done that, with this specific car. They did a full scan last year but couldn't print it out because their printer was broken.

In any case I can't clearly defend this path but should know in 5-6 days.

I'm still open to other suggestions based on my prior posts and codes so if you have a notion, I'm open to it.:confused:
 
#29 ·
The symptoms are that of a cps. It starts and once warm shuts off. Once it sits for a while it starts fine. My cls did just that. Started perfectly and I took it for about 500 yards to pick up food before going home. Shut car down and went in. When I came out it would not start. When the rollback arrived it started right up. The driver looked at me like I was nuts and I told him to rollback it to his garage and change the cps which he did and I have had no problem since. My cls does have a cps code that it throws. I believe the early ML's did not have a code for the cps. But you want to get the transmission issues addressed. And unfortunately your OBDll scanner won't erase of clear the transmission module codes. You neither need a high end scanner or a Star system. Good luck.
 
#30 ·
CPS and thanks



Thanks, I was beginning to doubt my conclusions but your comment about my scanner not seeing the CPS code and my inability to clear some codes sealed the deal.

The unit will be here in a few days but I have concerns about being able to change the sensor myself. I can't see the bolt and can't really identify the connection cable where it attaches. There is some sort of flange covering the area. I'll get my mirror out when the part arrives and then decide.

I was able to drive it 5 miles to the car rental return station before it died but 13 miles of freeway driving to the dealer is a risk.
It drove from the dental office to home, maybe 10 miles, but that was at night.

When this is over my wife will be happy and I will be exceedingly happy.

I think the dealer does a free tow to their shop, not sure about that.:smile:laugh
 
#32 ·
Sensor Replacement question



Sounds like a great idea but with my artificial knees I try to avoid heavy lifting. I may just call a mobile mechanic after the part arrives because, as I is, the car will drive some unknown distance. Last time I tried to remove the jack it was wedged in from age and it took a crowbar to get it to slide out.

I have a question about the connector. I can't see the bolt nor the details of the connector. Looks to be covered by a couple of wire bundles that may attach to it and by a black flange that may be part of the connector.:confused:

QUESTION- Do I have to squeeze the connector to remove it or does it side right off if I am able to grab it? Maybe my inspection mirror will show more but I'm going to wait until the part (hope I ordered the right one) arrives so that if I am successful I can do the job. If the wrong part I can replace the cable and the car will still drive a few miles. [I have to put on long sleeves before I do anything because I take blood thinner and a small bump becomes a bruise, not serious but an issue so I only want to do this one time.]

I must say much thanks to this forum. I was able to rebuild my SL500 power steering pump and check the cam/lash oiler tubes based on info in the R129 threads. Only remaining thing on that car is the noisy secondary air pump which only makes noise for a minute or less (waiting for it to fail completely) and the hydraulics which are not in the budget right now. In any case, I won't have to sell the SL now.

I'll start the job, long sleeves and gloves, etc. when the part arrives. As it is I know the ML will drive 5-10 miles (maybe) and I want to keep it that way until I have the part installed.

Again, thanks so much for all the consideration and help from this group.

Got two responses this morning and thanks to everyone here, the greatest.
 
#33 · (Edited by Moderator)
All bets off- A new inspection and finding!

Just took another look and found that the big mess of wires and the flange I have been obsessing about are back on the bell housing.

There is a simple single-wire going to what must be the plug I'm looking for on the engine, just ahead of the bell housing and slightly lower down. All I need to know is whether I must squeeze or just pull. I haven't even used my inspection mirror but I was clearly looking at the wrong part.

I believe I will even be able to see the bolt and I have the tools ready.

Now I wonder what that set of wires is that goes to the bell housing . . . another sensor?

Do I need to squeeze to release or just pull the connector body?



What a great group!!!
 
#35 · (Edited by Moderator)
New discovery pictures

All bets off- A new inspection and finding!

What a great group!!!
Not sure what piece needs to be lifted to release the connector but a small camera seems to show the right connector. Pictures attached.

The wiring bundle that goes to the bell housing is just out of sight to the right of the second picture. :eek

Regarding the connector in question, it seems that I will have to lift the bail, or, push a lever down to release the connector from the socket.

The wire is much smaller than it appears in these pictures, about 1/16 inch in diameter.
 

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#34 ·
There's a release tab you push down with your thumb while pulling out the connector.

Make sure the engine is not hot

There are areas on the engine that are sharp and can cut so you have to be well kitted & extra careful.

Or better still let someone help you with it. Not necessarily a mechanic
 
#37 ·
Release tab



Thanks,

It will be cool and I have a long sleeve to protect my arm. I think I will be able to do it without even looking. My only concern is to retain the bolt, can't get my driver magnetized so will use tape to jam it. I saw a picture here with what seemed to show a magnet in the driver.

I saw one video where the person un-bolted it before changing the part on the cable.

Just as a side note, we bought this house, new, when I moved back to Oklahoma from living in California for more than 60 years. I have been given several digital cameras by an old work mate from Atlas missile days but had already bought a compact, low end camera. I have used it to collect S/N from the A/C and other items I couldn't get behind. I just thought about using it this morning and it really helped. Blind shooting but autofocus. Wonderful tool.

How's the weather down your way?

This will be a happy household in a few days.:laugh
 
#38 ·
Tab



Thanks, got it.

I ordered the MB part number based on a picture sent here based on my VIN number. I sort of think that my sensor is the single-locking tab version.

I think I will be able to check that but in any case it will be here in 2-3 days.

Amazon listing 0031532828 :) [That is actually an MB number] (MB changed parts in mid-engine run)

Thanks again.
 
#39 ·
The basic difference in the two styles is that one is a dual tab/pin connector and one is a single connector.

They also used that sensor on a plethora of models. So the single and dual connector versions have both
the part number revised.

I am assuming you ordered the Bosch. If not please see if you can cancel the order and get the Bosch. I have
gotten the Bosch from Amazon for the E500 and actually keep it in the car as a spare.
 
#40 ·
Bosch or not



Well, sadly, I ordered what Amazon calls "OEM" model. I just found the actual vendor and talked to them by phone. They say they have just the average returns on that part (all electrical parts have returns I know) but they are willing to exchange it for a Bosch if it fails. The term "OEM" was generated by Amazon and I trusted them.

Since it has been shipped and will be here in a day or so, I have decided to install it for now and then decide whether to declare it as failing later. I remember going through two budget MAS sensors before I sprung for a Bosch but I have to get this car on the road soon.

I do understand that I have to reset the car computer and will have to look that up. I think it involves some interaction with the accelerator pedal. I have the procedure somewhere, I hope. I've done it in the past . . . I believe it tells the transmission to re-learn the driving style and hope that's what is needed after the new sensor is installed.

Anyhow, if the car runs well I'll search for a Bosch and put it in later. I sort of think the Hall devices all come from the same semiconductor house.

Thanks for the response. :smile
 
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