OBD pinout and diagnostics (update)

As a follow up to my introductory post:

3 OBD scanners fail to communicate with my ECU.. Autel, Innova and the cheap red HF scanner. Connector pinout yields the following (using pin 5 as grnd) Key on Eng off.

Pin 1 10.6v
Pin 2 empty
Pin3 .o5V
Pin 4 grnd
Pin 5 grnd
Pin 6 empty
Pin 7 11.3v
Pin 8 12V
Pin 9 10.4v
Pin 10 empty
Pin 11 0v
Pin 12 empty
Pin 13 11.2v
Pin 14 empty
Pin 15 7.6v
Pin 16 12v

This was a fleet vehicle that had a GPS box installed, I removed it. Everything else is in tack.

Also the turn left turn signal is operational to at least the relay (it clicks fast but no lights, dash or otherwise) bulbs and fuses good.

Would a failure in the fuse box disable communication to the ecu and also muck up the left turn?

Am I looking at a trip to the dealer for possible ECU repair?

How are these guys?

http://www.mercedesecm.com/sprinter-ecm.html

I spoke to my local Autel dealer and asked about a scanner that would 'talk' to my Sprinter. The only one they would guarantee to do so was the 802 (or better) but being a Euro spec. it has the round 14 pin socket so I also needed an adaptor. It does the job and will access pretty much everything.

What model year?
You can download a 2003 and 2006 service manual from http://aie-services-2.net/Sprinter/
The "bus communcations" section of the wiring diagram (8w-18-5) has the diagnostic socket and what goes where.
A normal (i.e. not MB intelligent) OBD scanner only uses a couple of the pins (3 and 7 probably) for data, plus power (16 probably) and ground (4 and/or 5).

All of the other lines go scooting off to talk to individual modules' K lines, and normal OBD doesn't use those.
Things like the DAD, DRB-III, expensive Autel and iCarsoft talk to all of the lines.

--dick

Thanks guys.. off to the independent to for a little diag. I have pinned out everything I feel that my findings are as expected for an otherwise healthy system (aside from TCM/Radio K line pin 11 showing 0v, regardless). I have a clean connection from the DLC to ECM pin 7 and 31, all connectors looked clean. Being a fleet vehicle someone could have plugged in something and mucked up the comm port in the ECM. I'll see what they can do. I will post my findings.

look at the bundle of wires that is behind the battery it rub against the AC pipes etc. my # 17 fuse used to go out , no power to #2 wire of the egr valve and found out that in the bundle were two wires that lost the insulation and were cousin false contact and all other things, including no power to my AC compressor, O2 sensor and turbo. I hope that these is the only problem that you could have but on mine I still have issues with wiring. good lock,

Here' s a page that lists the various manufacturers' "what pins have to be there to call it OBD-II": http://pinoutsguide.com/CarElectronics/car_obd2_pinout.shtml

The Sprinter seems to be ISO 14230 (KWP2000), so pins 16 (batt) for 12v, 4 and 5 for ground, 7 for the K-line, and 15 as an optional L-line are all that's required for OBD.
The K-line is "high" when not transferring data.

The T1N Sprinter's pin 15 is a common data line to the Instrument Cluster (so everything it knows could be sent down the wire), the Automatic Temperature Control Module (heater/airCon/Booster?) and the Cabin Heater module ... so i don't know if it's also serving as the optional L-line.

Sprinters' OBD sockets newer than 2006 are CANbus systems, with OBD pins 6 and 14 being "the bus".
On the 2006 Dodge circuit diagram, there is no (documented) connection to those pins on the Sprinter's OBD socket.
The "pinoutsguide" page suggests using an ohmmeter across 6 and 14 ... if you see about 120 ohms, you've got a CANbus connection there.
The Sprinters certainly use CANbus for inter-module communications, but the pre-2007 models didn't necessarily give us easy access to it.

giftshopduane wrote that his pin 12 was "empty"... on the Dodge schematics, it shows the AuxHeater, CentralTimerModule (i.e. the door locks) and Security System Module talking to that pin.

On my DAD's connector, pin 8 was broken off when i got it... so that means that it cannot access the ignition-switched fuse line (that also feeds the brake light switch).

--dick

For future reference heres the list of what goes where on the 16pin OBD DLC as far as a 2006 basic 118" cargo van goes..

Pin 1 = SKREEM (White/Dark Green)
Pin 2 = Empty socket
Pin 3 = Eng RPM socket 18@ECM (Dark Green/Yellow)
Pin 4 = GRND (Brown)
Pin 5 = GRND (Brown)
Pin 6 = EMPTY
Pin 7 = K ECM socket 31@ECM (this is the OBD data line) (Blue/Yellow)
Pin 8 = Brake Lamp Sw/ABS Sw. Fuse #1 (Black/Blue/Dark Green)
Pin 9 = Shifter antilock (Blue/Black)
Pin 10 = Empty
Pin 11 = K Line TCM/Radio pin A2 (blue wire to radio despite what the diagram said) (Blue/Yellow)
Pin 12 = Empty (this is the AUX heater socket)
Pin 13 = Airbag control module (Black/Red)
Pin 14 = Empty
Pin 15 = Instrument cluster/Auto Temp Ctrl/Cabin Heater (White/Grey)
Pin 16 = 12v constant to fuse #2 (Red/Yellow)

Not everyone can firmly grasp the concept of wiring diagrams, I hope this helps.

Unfortunately, using a voitmeter to check out the lines won't tell you much except for pins 4&5 (which are supposed to be ground potential), pin 16 which is always battery voltage through a fuse, and pin 8, which is 12V when the ignition is on. Pin 16 is probably the one which provides power to the code reader, and pins 4 and/or 5 provide ground, so if those are working, that's about as far as you can go with a voltmeter.

The OBD-II or Sprinter-specific code reader is supposed to pull up the lines it is reading through a ~500 ohm resistor. That is then pulled low or allowed to remain high by the reader or the microprocessor depending on which is sending or receiving data at the time. Do not attempt to do that manually. Since the reader is supposed to provide this, you really can't tell anything without a reader connected, and then a voltmeter will not tell you anything useful. You would need an oscilloscope to see data activity, but even that would not tell you whether or not both sides are actually working and/or why. For that you'd need to build a custom testing device or acquire specialized test equipment to see the actual data flowing.

However, you can get pretty darn far with a Sprinter-specific code reader.

There are multiple microprocessors connected to the OBD port connector's lines. Some lines have only one processor on them; other lines have several processors connected. For example, pin 15 has three different processors talking on it (the instrument cluster, the AC unit, and the heater booster).

If you have tried multiple OBD-II code readers, and can't get any to talk, remember that they typically ONLY talk to the ECM K-line. You could go to dealer - or someone with a DAD or one of the iCarSoft readers - and have them try their specialized readers that can talk to ALL the Sprinter K-lines.

I would doubt that all the K-lines are shot; with a Sprinter-specific reader, you would see which functions work and which don't, and prioritize repairs for those devices which don't respond at all. One could be the ECM, and it probably isn't the whole ECM, but just the interface circuit inside the ECM that's connected to pin 7. (This is a guess from electrical engineering experience, not Sprinter repair experience.)

If someone applied 12V directly to pin 7, that would probably fry the pin 7 interface circuit in the ECM, but the ECM itself might remain operational. But it won't talk OBD-II again. The interface is not intended to handle much more current than can flow through a ~500 ohm resistor, again, applied only by a code reader.

EDIT - the old school 12V testers that have a light bulb in them? those can fry logic pins.