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Lou P.
Lou P., ASE Certified Technician
Category: Ford
Satisfied Customers: 4063
Experience:  Have been working on Ford GM and Chrysler for 15+ years and ASE master certified.
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Bill.We have just changed the timing belt on a 2008 Fiesta

Customer Question

Hi Bill.We have just changed the timing belt on a 2008 Fiesta and now have a no start with intermittant firing and the fault codes P0339 and P0335. Also U0073.
Any ideas where to look?Timing has been checked 4 times by both mechanics and is spot on.
Submitted: 1 year ago.
Category: Ford
Expert:  Lou P. replied 1 year ago.

Hello. The issue will not be the timing. It will be the crank sensor or the sensor wiring. Have you checked the wiring around where you were working to make sure it was not pinched ? Or damaged? Did it run fine before the timing belt? Those two codes you have are electrical related meaning there is a problem with the wiring or sensor. Not a issue with timing. Unplug the wires and with a meter test for power and ground and signal. Your sensor should have 3 pins and there should be a ground on one and two voltages on the others let me know what you find and we can continue if needed. I am here to help. Lou

Expert:  Lou P. replied 1 year ago.

This should be how your sensor looks yes?

http://m.ebay.co.uk/itm/271350200765?_mwBanner=1

Customer: replied 1 year ago.
Hi Lou
Yes that is the sensor.I unshiethed and checked the wires and they look undamaged.When I am looking at the live data the CPS signal drops to 0 when cranking,this is when the engine will not fire.It reads for about half a second then drops to 0 for about 3 seconds then repeats.I will check for signals this afternoon when the ramp is free.
Expert:  Lou P. replied 1 year ago.
Ok the fact you have a scanner is excellent. A reading that is not reading the actual cranking tells me the sensor may have failed as long as the power and grounds are accurate. Also if you have a cam sensor try unplugging it. I have had bad can sensors pulling all the voltage away from the circuits because they usually share voltage with the crank sensor. Hope this information helps. Let me know what you find. Lou
Customer: replied 1 year ago.
Hi Lou
Pin 1 yellow wire shows 5v
Pin 2 white/red is 7.4v
Pin3 brown/red is a good earth.
Tested with the sensor unplugged at the connector KOEO
Yes it was running fine before.Thanks,
Simon.
Expert:  Lou P. replied 1 year ago.
Ok the 7.4 volts concerns me. Wiggle the wiring while testing and see if the voltage changes
Customer: replied 1 year ago.
No it seems stable at 7.42
Expert:  Lou P. replied 1 year ago.
Ok that wire will be the one that should have a return signal from the cam sensor , so you may be actually tearing voltage through the ECM , I don't want to say the ECM has failed but you should really not have voltage on that wire that high. I would replace the crank sensor. Before you go any further.
Customer: replied 1 year ago.
Ok will order one tonight and get back to you with result.
Thanks.
Expert:  Lou P. replied 1 year ago.
No problem. I'll did what I can to help. This may just be a HUGE coincidence. Also when you remove the crank sensor make sure to look into the hole and make sure you can see the part of the crank that the sensor reads. Hope this information helps. Let me know. Please take a second and click the box and rate my service GOOD OR EXCELLENT SERVICE if you feel I have been helpful and please request me in the future. If you feel I have not been helpful please DO NOT RATE BAD OR POOR AND WASTE YOUR MONEY , I will opt out to see if another expert can provide more or better assistance so you're not wasting your money!!. Thanks for choosing just answer. Lou. also , if you feel i deserve one , BONUSES are GREATLY APPRECIATED ! ūüėČ Keep in mind then when you rate it does not end our conversation. you can still return here to me for follow up information if needed, Lou.
Expert:  Lou P. replied 1 year ago.
http://youtu.be/itMXO56z1tw
Copy and paste that. It is a video link. I'm thinking the sensor should have 12 volts on the crank wire you measured 7.4 volts at , which may indict a failed ECM BUT if the same voltage is shared with another sensor then another sensor could be the issue. I say swap the crank sensor first and then we see what happens.
Customer: replied 1 year ago.
Hi Lou
Swapped the sensor and it is just the same.Do you have a wiring diagram? or can you tell me which other sensors share the same circuit so I can test them? Unplugged the cam sensor and still have 7.4v at terminal 2.The chassis number is *****
Thanks.
Simon.
Expert:  Lou P. replied 1 year ago.

Simon that is the best I can do. I don't have access to a diesel fiesta model my apologies. I will opt out and see if another expert can help. I wish you luck. Please let me know the end result when fixed.

Customer: replied 1 year ago.
OK thanks.