sun-sense

So, the 2002, ML320 stops when it get's hot and won't start (the engines turns and tries but judders and all the lights come on). After 20 mins or so, it starts right up but after 5-10 minutes, the engine shuts down again. I suspect the CPS (Crankcase Positioning Sensor).

I borrow someone's several years old scanner but it doesn't connect. OK - I should get a scanner as all post 96 cars need this device and check the forums and decide on the Actron CP-9580a.

Try it on auto ID and all I get is 'LINK ERROR'.

Try it on manual. Select European, 2002, truck (yes, they class it as a truck), mercedes, and there it is, ML320, so I select it. Long wait for 30 odd seconds and then 'LINK ERROR'. - Sigh.

I've looked at the pins. The ones that are there look flush. I know that a couple of years ago, the mercedes dealer used one as they told me the there were no codes (which was good) after some work.

I'm going to order the 'Bosch 0261210170 Crank Position Sensor' via amazon, $40 + $3.99 next day as I have been off the road since Thursday.

So where do I start looking for the OBD 'Link error' problem ?

sun-sense

Update: I found some docs on OBD and checked between pin 4 (Battery ground) and pin 16 (battery +) and its good, so no blown fuse. I didn't really expect it as the scanner comes on when I plug it in ie. it draws power from pin 16.

So what should I check next ?

Is their a second diagnostics port in the engine compartment ?

I haven't found one yet.

sun-sense

I managed to find a diagram and checked fuses again.

I had a weird result on fuse 22. Its blackened on one side but checks out on continuity. The voltage was inconsistent. I swapped it out and now have good voltages and now the Actron CP-9580a works (329 PID - Parameter Identification Data) codes, but only under manual selection. I'm wondering if there is a loose or bad connection or if was just the fuse. Time will tell I suppose

No codes though.

I ran the engine for 30 minutes and it never stopped.

Not sure this is an intermittent fault and am waiting for the CPS delivery today.

I noted during some of my searches that there is a fan under the fuse box/computer areas that sometimes slows down or fails causing overheating issues. I'll look into this as well.

Any other ideas or comments ?

I have noted that there are a lot of reported intermittent issues that come and go. Time will tell if both problems are permanently or temporarily fixed ;-)

sun-sense

Finally...the engine stopped.

The Actron CP9580a gave me...

P0335 mod 1/1 $10 Crankshaft Position Sensor A circuit malfunction - CONFIRMED.

Still waiting for the sensor to arrive.

sun-sense

Time to finish this thread off.

The CPS came late Wednesday.

Installed it AM Thursday. Took about 10-15 minutes.

Tools used, flashlight, #8 torx socket, 18 inch extension bar, ratchet.

Its half way down the rear right facing the front of the car.

Reach down and disconnect clip. Half undo torx bolt, pull the CPS up a bit, undo the torx bolt all the way. Pull the CPS out retaining the bolt.

Putting it back in. Push in sensor. Rotate so you can see the torx bolt hole. Reach down and finger tight/start the bolt into the whole at least a few threads. Finish with the socket and extension. Clip back on.

Start engine. Turn off and attach the scanner. Clear codes. start engine and run and drive.

Its been 4-days now and no further issues so we can call this thread...

FIXED AND CLOSED.