open circuit

[marko1]

Hi everyone, just joined after buying a w639 vito 3.0 cdi. I have a misfire on number four cylinder and my icarsoft reader says open circuit with fault code 10dd00. i have renewed the wiring from the ecu to the injector and also the injector itself. I have also fitted another ecu brought from The ECU Doctor but still the same fault. I am at a loss of what to do next so any help gratefully received.

 

[Supernoodle]

Whoa, test test test before you throwing parts at it. Electrical issues should be easy to test, much easier than the such and such signal is implausible type.

Even without any electrical test equipment there are some things you can do.
Unlike most other components injectors are switched on the high and low side. So the problem could be with either. If you had an injector short circuit fault you would disconnect the injector to see if it was the injector or wiring. Similarly with an open circuit I would intentionally disconnect the injector and short out the two pins in the injector plug on the harness. You want that fault code change to a short circuit fault.If it does, there is no problem with harness or ECU. If ECU still reports open circuit that suggests either wiring or ECU.

You replaced the wiring, did that include the female pins in the connectors? If someone has been poking around in there with probes or worse paper clips that can open them out enough that they don't make good contact with the male pins. You shouldn't need I replace them but you do need to check them for pin grip. The injector pins will be the larger ones, so easy to visually check too.

 

[marko1]

Whoa, test test test before you throwing parts at it. Electrical issues should be easy to test, much easier than the such and such signal is implausible type.

Even without any electrical test equipment there are some things you can do.
Unlike most other components injectors are switched on the high and low side. So the problem could be with either. If you had an injector short circuit fault you would disconnect the injector to see if it was the injector or wiring. Similarly with an open circuit I would intentionally disconnect the injector and short out the two pins in the injector plug on the harness. You want that fault code change to a short circuit fault.If it does, there is no problem with harness or ECU. If ECU still reports open circuit that suggests either wiring or ECU.

You replaced the wiring, did that include the female pins in the connectors? If someone has been poking around in there with probes or worse paper clips that can open them out enough that they don't make good contact with the male pins. You shouldn't need I replace them but you do need to check them for pin grip. The injector pins will be the larger ones, so easy to visually check too.

Renewed both the wiring with new pins from Mercedes, apparently had the last two in the country. I have now refitted my original ECU and sent replacement back to The ECU Doctor who have been very helpful. Still got the original fault and also bought a noid lamp and definitely no output from the ECU. Can not think of anything that would affect just one injector so completely stumpted as to what to do next.

 

[BoristheBounce]

Example.......

On my BMW Z4 I had a fault coming up that it wasn't running cleanly on all 6 cylinders, and that there was probably a fuel/air fault on I think it was 3 of the 6 cylinders.

The fault was......that during service they hadn't replaced the dip stick fully therefore it was drawing in air!

Push in dip stick, fault gone!

Fault finder can only give so much info. and the secret is the operator, a good one that knows what they are doing.

 

[Supernoodle]

Example.......

On my BMW Z4 I had a fault coming up that it wasn't running cleanly on all 6 cylinders, and that there was probably a fuel/air fault on I think it was 3 of the 6 cylinders.

The fault was......that during service they hadn't replaced the dip stick fully therefore it was drawing in air!

Push in dip stick, fault gone!

Fault finder can only give so much info. and the secret is the operator, a good one that knows what they are doing.

Open circuit is clearly electrical. You can get a cylinder balance/contribution fault that indicates performance of that cylinder is low. That is not electrical. You have to look at the description carefully.

 

[BoristheBounce]

Open circuit is clearly electrical. You can get a cylinder balance/contribution fault that indicates performance of that cylinder is low. That is not electrical. You have to look at the description carefully.

Not saying its related to this case, only that the fault finder is only as good as the mechanic interpreting the data supplied by it.

 

[Supernoodle]

Renewed both the wiring with new pins from Mercedes, apparently had the last two in the country. I have now refitted my original ECU and sent replacement back to The ECU Doctor who have been very helpful. Still got the original fault and also bought a noid lamp and definitely no output from the ECU. Can not think of anything that would affect just one injector so completely stumpted as to what to do next.

You only had to check the pins, no need to replace. Even if opened out they could be closed back up.

You have got the correct injector haven't you? Doing the short circuit test would prove that. Disconnect the others one at a time and check the open circuit codes these give to confirm too.

Noid lights usually won't work on common rail injectors, especially if piezo.

 

[marko1]

Problem solved. After a lot of head scratching discovered that previous owner had put ecu socket pin in wrong place, no idea why it was removed. Runs lovely now.