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05 C230 Sedan Sports Package
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Discussion Starter · #1 · (Edited)
OBDII port not powering up

Before creating this post I did a search on this topic but found no results.

Recently I took my car to get a smog check as my registration is due for renewal soon. When I was at the shop the technician said that his machine was unable to read my car's ECU. He specified that he just could not make a connection to the ECU at ALL; he took the time to explain that a lot of times when cars come to his shop the machine is not able to read the readiness portion for the cars to pass smog, something that can be fixed by driving the car around for several hours, but that was not the case with my car. He even took an OBDII reader and plugged it in to the port in my car to show me that the port is not working, the machine was not even powering up at all.

When I got home I took an OBDII scanner, the same one I have used several times in the past to read the codes, and the machine did not connect at all to the car, simply the OBDII scanner does not power up. When I move the key to the ignition position the CEL light comes on as it should and goes off when the engine starts.

I am even afraid to ask, what am I looking at in this case?.

- New ECU ?
- Blown fuse ?

I have not ever heard of something like this.
 

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05 C230 Sedan Sports Package
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Discussion Starter · #2 · (Edited)
I found out what the problem is. In case this ever happens to someone in this forum there is a fuse titled "Diagnostic Port", for my particular model is bay number 62 (15 AMPS fuse).

I knew where the fuse box is located in my car (engine bay) but I noticed there is no diagram for the fuse assignment. I had to do a search in this forum to locate where the diagram is located in my car. There is a folded up diagram in the fuse panel on the driver end of the dashboard. All I had to do as to pull the end cap off with my fingers, there it was, folded waiting for me.

Once I got a hold of the fuse diagram I had to look carefully on the list, in the beginning I didn't find what I was looking for because I was looking for ECU Port. I was also looking for OBD port and didn't find anything either, at this point I was getting frustrated. Until I decided to go down the list line by line, and found "Diagnostic Port". I crossed referenced it with the port assignment and capacity.

What it is interesting is that there was no fuse in the bay, big mystery. I bought the car almost new from MB dealer with less than 15K miles and always had it serviced it there. In the past I had couple of CEL lights and took it to MB when it was still under warranty and they were always able to pull the codes. The only thing that I can think of is that last year my alternator went bad and had to be replaced. In order to save a few bucks I took it to a local shop and maybe at that shop the fuse was removed. Needless to say, I installed a fuse and my diagnostic port is working again. Now I can take my car back to get it smog checked. I still have a pending code when the alternator went bad but that should not have any effect in passing the smog check.
 

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'01-E320 & 02-ST2
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I would have guessed a blown fuse...but not a missing one, that's for sure! :D

Re: the dealer, it's likely they never connected to the OBD-II port. They usually plug in SDS to the 38-pin connector under the hood and talk to all of the car's systems that way.

Just musing, but it's possible that the PO had a fuse blow and simply pulled that one to use in the other location. In that case I wouldn't fault the selling dealer, since no one really inspects the fuses to see if they are all there. ;)

In any event, nice detective work, and glad you got it resolved inexpensively.

Good luck.
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550 FORMER: C300, ML350, CLK550 Cabriolet, C240, ML320, 300TD
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I don't believe the W203 has the old 38-pin connector under the hood. But, I believe that the "C4" version of SDS (the wifi version most shops have now) has its own power supply, so it can talk to the car's systems over OBDII without that fuse. The older C3 version of SDS (with the RS232 breakout box), like most generic OBDII scanners, does require power from the OBDII port.
 

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1999 E320 4Matic Wagon
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My 1999 E320 has a dead 16 pin OBD II port under the dash - it died a couple weeks ago shortly after I had plugged my wi-fi transmitting code reader into it and was getting ready to read the codes on my Iphone when I lost signal. I assumed that the transmitter in the code scanner had failed, not the port itself. I had used this code scanner several times previously.

I didn't pursue it any further until last week when the check engine light started flashing and I pulled the car over to the side of the road and turned it off. I turned it back on and the check engine light was solid and not flashing, so I drove to the next town and stopped at an Autozone to have them scan the codes. Their scanner couldn't get a connection either, so now I assumed it was the port, not the scanners.

Next I ordered a 16 pin to 38 pin round converter cable from ebay to try a basic scanner on the 38 pin round socket under the hood. I received that cable yesterday and took the car to an Advanced Auto store this morning and they tried their basic scanner with this converter cable on the 38 pin socked and still had no communication or power, so I still can't read my codes.

I just double checked the fuse three fuse diagrams that I could find in the car, and didn't find any labelled in a way that suggests that it might be related to the OBD II port, diagnostic port or anything similar.

So, I'm open to suggestions for what to check next. There aren't any shops open today to see if the codes could be read with a self-powered scanner.

Thanks.
 

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1999 E320 4Matic Wagon
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Check fuse #62, under the hood.
Thanks for that suggestion. I just double checked the fuses under the hood in the compartment with the 38 pin port and the diagram only shows fuses up to #45 under the hood or under the back seat.

Is there another fuse location under the hood?

My 1999 E320 is a W210, rather than a W203 as the OP, so the fuse layout is likely different.

Thanks again.
 

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W210 Section Moderator
1998 E320 base sedan @ 235K miles
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It is at the passenger side under the module box lid. Remove the lid (4 bolts), find the K40 fuse / relay module. It is fuse-1 (7.5 amp). The rightmost fuse as you look from the front of the car.
 

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1999 E320 4Matic Wagon
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It is at the passenger side under the module box lid. Remove the lid (4 bolts), find the K40 fuse / relay module. It is fuse-1 (7.5 amp). The rightmost fuse as you look from the front of the car.
Well done mrboca! That 7.5 amp fuse was, indeed, blown.

I replaced it with the phone fuse 23 and tried my Veepeak VP01 WiFi scanner and still didn't get a signal, so I checked the fuse again and it had blown again.

I replaced the fuse again with washer fluid heater fuse 42, removed the scanner from the OBD II port and started the car, ran it for a couple minutes and checked the fuse again and the fuse is still intact.

My conclusion is that the VeePeak VP01 OBD II scanner has a fault that caused the fuse to blow, so I'll be needed to purchase a new scanner. I'll stop by Advance Auto shortly to see if they can read the codes, now and get some replacement fuses.

I'll check the sticky's for suggestions for a reliable WiFi transmitting OBD II scanner.

Thanks for all of the suggestions everyone.
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550 FORMER: C300, ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Thanks for that suggestion. I just double checked the fuses under the hood in the compartment with the 38 pin port and the diagram only shows fuses up to #45 under the hood or under the back seat.

Is there another fuse location under the hood?

My 1999 E320 is a W210, rather than a W203 as the OP, so the fuse layout is likely different.

Thanks again.
Oh, sorry, I did not realize we were talking about a W210.
 

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2006 MB C230
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I know this an old thread, but my scanner lights up, indicating the port has power, but when it goes to scan for connection, it cant find a language to communicate. Any ideas? I have an 06 C230.
Thanks,
Karl
 

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2006 MB C230
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It's a cheap one from WalMart, a HT 309. It's getting power, but when the scanner tries it's assortment of connection possibilities, it doesn't find a way to communicate. What do you mean that the module may not be powered up? I'm kind of a novice at this :)
 

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W210 Section Moderator
1998 E320 base sedan @ 235K miles
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It is trying to communicat with the ECU using different protocols (as it does not really know what the car is), It sends a signal to the module and waits for a response. If no response it tries other protocol (language as you called it). If the Engine computer is not powered (bad fuse) or defective, it cannot respond. Make sure you set the ignition switch to "run".

What is the problem ? Does the car start and run ?
 
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