Car Connection

Peculiar situation.😟 My 09 ML 350 sat in the garage for a month and a half while i was out of town. When I returned home, I cranked it up, it started on the first try and ran great for a minute while I fiddled with the radio. Then it suddenly died; the dash lights came on, and the radiator fan came on full blast! I tried re-starting it, but in position 2, could not get even a click from the starter. After a couple more attempts, I gave up and attached a 6 amp battery charger to the under-hood terminals. After 2 hours of charging, the battery voltage showed 12.4 volts on the dash read-out. I cleaned up the key lens and slot with alcohol just to be sure the key was communicating with the EIS. I started the car up again, and it ran fine for 45 seconds, then turned off again. The dash lights also came on and the radiator fan running started at full speed again. I'm totally stumped. If the EIS was bad, I wouldn't get any dash lights, and the car wouldn't get any dash lights, and the car wouldn't start. Against my better judgement, I replaced the main battery just to see, even though I was sure my current battery was good. The auxillary battery was fine, ... Looked new and tested at 12.4 volts.But still the same crap! It starts up and engine runs for a about a minute or less, then turns off and the radiator fans come on full blast!Very frustrating !😠😡 Any suggestions would be greatly appreciated.

ItalianJoe1

Sounds like you are losing communication to the PCM or something on the powertrain CAN, have you scanned it? Also, you said you had to charge the battery for 2 hours to get it to 12.4, so it was very weak. Is the truck charging the battery when running? What's the voltage display on the dash when running (go to service reset menu area, it will show it)

Car Connection

No I haven't scanned it, will have to go get a decent scanner tomorrow. When I charged it for 2 hours I was using a small 6 amp charger, so 2 hours is not unreasonable for charging a 900 amp battery that had been sitting in the SUV being drained for 7 weeks. Also after that I went out and bought a brand new battery and replaced the main battery. The SUV is still doing the exact same thing. It will start up and run smoothly for less than a minute, then the engine just cuts out, and the radiator fan comes on full blast. After that it will not start unless I let it sit about 15 or 20 minutes.Then it will start up again and do the exact same thing! When it is running, the battery voltage display shows 14.1 volts. Hence the alternator seems to be working properly.
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Maj. Dundee

When a vehicle is laid up for more than 4 weeks, without removing the battery ground cable, it damages the battery irreparably.

Replace the battery, then read codes in all 25+ modules and delete them. Then you should be good to go. Scanner reader is necessary.

Car Connection

I had already replaced the main battery and tested the auxiliary battery. The battery wasn't the issue.. I think its the ECM
I finally got hold of a Foxwell Benz scanner, and pulled a bunch of codes off several modules with key in position 1., Some were old codes, but a few modules reported no communication with the ECM. I then turned the key to position 2 and managed to pull code 0521 off the ECM within the 45 seconds before the radiator fan started up full blast again. At this point the scanner lost communication with the ECM, From this I'm deducing that the ECM has a short or faulty component inside it (which is why the engine cuts off suddenly after running for 45 seconds) and will need to be replaced or rebuilt. Can anyone suggest a reliable and reasonable rebuilder for this ECM?

Maj. Dundee

The battery was the issue and it is not the ECM. Delete code 0521 while the key is in pos. 2. Then turn the key off and wait 10 secs. and check for codes again.

Skybase

This brings up a question for me... being that the battery is under the passenger seat, do I need to get up under there if i ever need to just disconnect the negative, or does the main ground run up to under the hood where the jump posts are? Can I disconnect from under the hood or is there another "primary" negative ground up under the seat somewhere? I guess, same with the positive. Does it run directly up to the jump posts for easier disconnect or no?

ItalianJoe1

The battery is grounded to the chassis near it's location, so if you want to do a hard reset from the battery, yes you will need to access it under the seat.

I do agree that you have some sort of issue with the ECM, but as stated, be sure to delete all your codes first and get a scan after the issue happens, see what comes up.

Car Connection

Its best to disconnect the negative terminal off the main battery under the seat. Its towards the back of the seat and the easiest to get to.

Car Connection

I cleared most of the codes from several modules with the key in position 1, but had to turn the key to position 2 to communicate with the ECM. I barely managed to clear code 0521 when the communication to ECM was cut off and the radiator fan started up full blast again. Now the truck wouldn't start again, and the scanner couldn't communicate with the ECM. I let it sit overnight with a trickle charger on the battery, and today I was able to read all the modules in position 2. Many of the error codes returned in various modules, "no signal from ECM" and code 0521 came back again with message "tumble flap intake manifold short circuit to ground of sensor lines". I cleared all the codes and this time the truck started up and ran for about 10 minutes, then died again. I let it sit for another hour, re-scanned the ECM and 0521 was back, along with some other non-communicate codes. I cleared them again, and this time I didn't lose communication with the ECM. Then I reset the throttle flap position, made a couple of other recalibrations available on the scanner and started up the truck. This time it ran for half an hour without cutting off. It may be fixed, but I'm afraid to drive it on the street in case the problem occurs again. I will try it with a friend following me in case it stalls in the middle of the road. I still suspect that the ECM may have a faulty component or broken solder joint in it.