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I made a mistake, I’ve been having plugged dpf problems with…

Customer Question
Ok, I made a mistake...
Ok, I made a mistake, I’ve been having plugged dpf problems with my 2010 Mercedes-Benz ML350, got fed up and pulled the ecm / cdi and sent it away to do the dpf add blue delete with JR performance chiptune.
Problem is I didn’t disconnect the battery first. When I had it on the bench I heard some electrical components cycle on the car and realized I hadn’t disconnected the battery. Yup bad move..
I put it back in and tried to start it. It cranks but won’t start. Well it tries to briefly but no joy.. my snap on scanner says 11A100 component y74 (pressure Control Valve) has open circuit. When I monitor fuel pressure it bounces back and forth from 7-37 psi while trying to start.
Does the ecm cdi need to be re-synced in order to get a run condition again or??
Submitted: 19 days ago.Category: Mercedes
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Answered in 13 hours by:
5/31/2018
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 18 days ago
Lou P. master tech
Lou P. master tech, Mercedes Technician
Category: Mercedes
Satisfied Customers: 6,008
Experience: 20 years Master Certified excellent fix rate and have access to factory wiring, and instructions.
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Hello my name is Lou.
I am going over your request now and will reply back soon with some info OR a few questions, Lou

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Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 18 days ago

first thing i want you to do is unplug the engine module again and check all the pins on the module to make sure none are bent.

usually as long as the key is not on then it does not matter if the battery is connected or not when unplugging the module . i am more concerned about the pins since the code we have is open circuit.

Lou

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Customer reply replied 17 days ago
I had a really good look at the pins already, and they were all good. Being that I had just rolled it onto the hoist, and it was in neutral I assume the key was on
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 17 days ago

ok so next is to unplug the valve and the module and ohm the wires to make sure they are good.

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Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 14 days ago

any luck?

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Customer reply replied 4 days ago
Hi Lou;
So I was waiting to get back to you until I had, looked after a few basic things. I took the mercedes to the dealership to get the CDI paired back with the vehicle after having the performance chip and dpf add blue delete done. They were super helpful. But I still have the Y74 pressure regulator open circuit issue. At mercedes they told me that the valve it self should have between 3 and 5 ohms across poles 1 and 2 it has 3.9. I also checked continuity of the wires from the valve to the cdi (pins 95 and 42) I got tone on my continuity testor, but when I checked resistance over the wires one was 0.1 ohms and the other was 4.3.
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 4 days ago

4.3 is no good, but tell me which color wire?

sometimes power is shared but i thought on this one it was direct to the module

in that case we cut and run our own wire and recheck

i thnk i fixed one of these before like this it sounds super familiar

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Customer reply replied 4 days ago
They are direct to the module, it was the wire to pin 42 which is the returning signal. I will splice in a temporary wire after work today and see if it will fire up. Ill let you know how it goes.
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 4 days ago

ok sounds good man

yes 4.3 plus the extra ohms of the valve would throw a code for sure

so the wire overlay would be a great test

let me know!

Lou

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Customer reply replied 4 days ago
Well still won’t start, I’m still having a fuel delivery issue. In the wiring guide that you sent me before. For pin 1-95 which is the one that has high resistance there is a note stating that the regulator gets a pulse and then no more pulses until the motor runs again. I’m wondering if I’m just no longer getting a pulse.
The mechanic at the dealer said I should check pressure from the low pressure pump. I’ve checked the fuse and the relay in the back of the vehicle, both good. What is the best way to check for fuel pressure on the low pressure pump?
Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 4 days ago
Remove the hose from the fuel filter and either tee into the line or dead end it
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Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 3 days ago

ok so then lets check the fuel pump by jumping the fuel pump relay

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Mercedes Mechanic: Lou P. master tech, Mercedes Technician replied 3 days ago

we need to jump terminals 87 and 30 of the fuel pump relay

look on the relay you will see the terminal numbers located on the bottom

Lou

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