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Gary
Gary, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 999
Experience:  Senior Technician
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I have a 2006 smart car diesel that will crank but not

Customer Question

Hey, I have a 2006 smart car diesel that will crank but not start. Has a new crank sensor. Not saying it's good. I have a p0500. Weird thing is all of the engine controls have been swapped from a running vehicle as the engine in this car had timing chain issues. The only thing we haven changed is the egr valve and the crank sensor. However a crank sensor was installed onto this engine in attempt to fix it
Submitted: 1 year ago.
Category: Mercedes
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

Check and make sure fuel is making it to the fuel filter and from the fuel filter to the engine.If the fuel filter itself is restricted it will cause this type of fault here and will need replaced.I have seen the fuel filters restrict as well as restricted or damaged fuel lines cause this type of fault here needing corrected/replaced.If this has already been checked and found to be o.k. let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
Hello. Sorry my first question was a little vague. We are a licensed shop and I should have told you all of the preliminary checks have been done. The injectors are not being turned on and p0500 is for the vehicle speed sensor (which I guess is the crank sensor) I pin tested the crank sensor circuits with no fault and I am going to install a different make of a crank sensor. As I can't really see it being anything else. Any ideas please let me know. I will let you know if the crank sensor fixes it
Expert:  Pete replied 1 year ago.

Besides the crank sensor itself at fault the only other thing I can think of here is the wiring to the sensor possibly being damaged needing repaired or replaced.

Thanks Pete

Customer: replied 1 year ago.
Installed the new crank sensor and still no signal to the injectors and no power at the injectors. Not a fuse issue. Again this engine and transmission assembly did this same thing in another car and since literally everything engine wise has been swapped. Only thing left is transmission related. This car did not have this issue before and we swapped the engine harness as well
Expert:  Pete replied 1 year ago.

Is the theft/security light on steady or blinking at all when cranking over the engine or when you release the key when it wont start?

Customer: replied 1 year ago.
No, theft light isn't on. I wish. And we didn't disconnect the battery and it has the original computer in it as well
Expert:  Pete replied 1 year ago.

Just to be sure here,this didnt have any issues until the wiring harness was replaced am I correct?

Customer: replied 1 year ago.
No sorry, I'm gonna do my best to explain this. The car that we took this engine from had this same issue, will crank but not start. However this engine only has 32000km on it. So the car that we put this complete engine and transmission assembly from has the same issue in the new car. The only thing wrong with the engine that was in the car originally was the timing chain was getting noisy. So we took every part off if that had to do with fuel and sensors as well as the starter and alternator. We used the harness that this car had because the car worked fine. The only thing left is the transmission and transmission sensors actuators that we kept from the car that had this issue. And this engine did run perfectly for about 30 minutes after the swap however quit after a short drive and now will not start again. I even grounded the circuit for the oil psi sensor to make sure the sensor wasn't faulty.
Expert:  Pete replied 1 year ago.

I apologize for the delay.

With a scan tool connected to the vehicle if you crank over the engine on the scan tools data list do you see an engine rpm signal at all?

Customer: replied 1 year ago.
it takes about 3 seconds of cranking and than it will pop up 340rpm and stay there. I did a signature test on the crank sensor and it looks like a weak ac sign wave. There is only 2.5 volts going to the sensor. I'm a Gmc guy with a lot of experience in domestic diesels and I know they all have 8 volt reference's to there crank sensors with the key on. But finding info for these smart cars is like pulling teeth
Expert:  Pete replied 1 year ago.

This is a tough one for me to answer myself here as my info is also limited with no wiring diagrams available on this here.

I will open your question up for others here to see if someone else can assist further on this as there may be others here that may have more info on what to check or do with this issue.I hope you can get this resolved with ease.No need to reply to my last post here unless it is a last resort as it will keep your question locked to me and others will not be able to view it.If you feel you want to continue to work with me on this feel free to reply at any time but keep in mind in some cases it can be difficult to fully diagnose or help repair this without seeing your vehicle.

Thanks Pete

Expert:  Gary replied 1 year ago.

I have read your story so far, and I feel for you with this issue.

Your P0500 is vehicle speed, not engine speed.

So output shaft speed sensor on the transmission.

I'd say you have a ground issue common between the VSS code above and the no-start condition.

Gary

Customer: replied 1 year ago.
I hear ya with the ground issue. But again there is only one ground from the engine to body as well as the body to battery. Less than .5 of a voltage drop from the engine to the battery while cranking. A schematic of the this would be helpful and as stupid as it may sound I think there is something on the transmission that is causing this not to start. Wether it's drawing down a reference or something
Customer: replied 1 year ago.
I hope I posted that in the right spot so people could look at it
Expert:  Gary replied 1 year ago.

Josh,

Is this car auto or manual transmission?

I'll see what I can find for a circuit diagram.

Gary

Customer: replied 1 year ago.
It is a automatic with the paddle shift
Expert:  Gary replied 1 year ago.

Hi Josh,

I think that you'll agree that 2.5 volts to the crank sensor needs to be sorted.

Difficult to find a circuit, still looking.

Gary

Customer: replied 1 year ago.
Thanks
Expert:  Gary replied 1 year ago.

Hi Josh,

I would disconnect all other sensors one at time while observing your crank sensor reference voltage. If it kicks up to 5v or even 8v, then possibly the last sensor is the cause.

I can't find a circuit, but wouldn't it be odd if the VSS is fed by the same feed.

And your P0500 could be a faulty VSS pulling the supply volts down etc?

Thoughts?

Gary