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Mike, Ford Technician
Category: Ford
Satisfied Customers: 39198
Experience:  Tech Expert
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Focus 06 model 1.6 start car, runs, but hunting, touch throttle,

Customer Question

Focus 06 model 1.6 start car, runs, but hunting, touch throttle, engine revs raise by about 200rpm check voltage at throttle body yellow wire voltage is only 2.0 volts, should be 5v yellow wire at ecu is also only 2.0 volts, fan cuts in and out at max speed sporadically. unable to clear codes in ecu, then whilst probing ecu 2v output suddenly switches to 5v shut engine off, able to clear codes, restart everything is perfect until next day when this all starts over again! y
Submitted: 4 years ago.
Category: Ford
Expert:  Mike replied 4 years ago.
Hello and Welcome -

My name is MIKE, Im happy to help you ..

Please tell me exactly what codes will not clear...

Too - please give me the vehicles FULL reg number - and mileage.

Rgds, MIKE.................................

Customer: replied 4 years ago.
Reg number LN05ZPU VEHICLE IS NOW SHOWING 86k but with previous dash ecu etc was95k just in addition the earths under bat tray have been removed cleaned and also piggybacked to the battery - term, the earths at ECU ie black with yellow trace, have been checked and double checked, even with throttle body plug disconnected the voltage at the yellow wire starts off at 1.9 volts and for some reason creeps up to 2.2 volts over the period of about an hour, you can leave the engine idling While testing, fan is cutting in and out at what is prob 70degrees gauge is not even at half way mark. The strange thing is whilst monitoring 5v supply output from ecu, suddenly 5volts are showing, you then shut off engine clear the codes of which I do not recall tonight but there are 13 of them are able to be cleared and everything is normal, in addition there is a symbol looking like a cog withe exclamation mark, that stays on whilst problem occurring.
Expert:  Mike replied 4 years ago.
Hello again Gary -

Thank you for your reply.

The first thing then to do if you haven't already is just test the feed / positives to the PCM - make sure they are battery voltage..

I stongly suspect you have a faulty PCM - you have ruled out the loom by replacing that - so if you are sure there are no contact / connection issues to the PCM and the various components in question ( you could do a resistence / contiunuity test ) - then that - coupled with all the codes that you cannot delete - point to a fault with the PCM internally.

I would suggest to have it sent of to a company for test / repair... I can give you a contact of acompany I can suggest if you wish or you can find ones that advertise to suit you on the net / google etc.. Just ask me if you want a number / contact though.

This , a faulty PCM, would certainly account for all the issues you describe Gary -inc not able to delete fault codes and inc the fan issues - as that is PCM driven too... It has to be your next move as above on this one..

Too - one of those codes should relate to the cog / exc light you have - no system fault there from what you have said - its all in the PCM - so thats the next move on this one for sure--

Let me know if you need anything more on this at all -

Please do click on the "OK rating to Excellent ratings" service for me now, Thank you for that... and you can get back to me anytime if you need / wish..

Best Rgds, MIKE.

Please note, you are rating the content of my "answer" - my help to you - not the "system" which can experience delays etc which are not under my personal control -or delays caused by "time -off" which we all have on occasion - Thank you.
Customer: replied 4 years ago.
Mike, the PCM.. is this the unit under the bonnet alongside the battery because this has been replaced along with dashboard and fuse/relay board inside the car,
If not where is the PCM ?
Also in scouring the Internet I have come accross posts regarding the battery, whether it is lead acid or silver cadmium, do you know which one?
Another update, this morning, connected voltmeter to under bonnet engine management unit, 5v output to throttle body, yellow wire, started engine, voltage was at 3.5v engine hunting and no throttle control watched voltmeter climb slowly til it it reached 4.5v then jumped to bang on 5v turned engine off, cleared codes, restarted and everything fine,
Expert:  Mike replied 4 years ago.
Hello again Gary -

Thank you for your reply...

Yes the PCM is by the battery -- I note you say its been replaced....and if with the cluster etc I suspect that was for an immobiliser issue... but do bear in mind that it doesn't mean its not faulty....

Anyway - further - yes re the battery - you should have a Calcium one on there - that car has what's called a Smart Charge system - so it needs the Calcium else things can be affected... ( Cadmium ) It may be worth changing it if you have the old lead one - see what happens..

Let me know Gary how you get on...

Kind Rgds - MIKE.

.................Please do click on the OK/ Excellent ratings for me as that's how Im credited for helping you - Thank you in advance for that...

You can and are most welcome to get back to me anytime you might need - clicking the OK ratings does not close you out at all..

Rgds, MIKE.