Hi,

Ford Focus 2003 1.8 tddi Intercooler.

Engine sometimes splutters and sometimes cuts out, and then will restart after ignition switch cycled. Seems to worse during wet weather (clue?).

Only recent diagnostic messages relate to low battery volts.

However, battery and alternator output are OK whenever I manually measure them. Battery connections, earth points and main fuses & relays all cleaned and vaselined

Where are the voltage sensor and voltage regulator located ?

Thanks in advance for any assistance

 

There isn't a voltage sensor. That is measured inside the engine ecu.
If the battery voltage is o.k. but the voltage to the engine ecu is not, I suspect some problem in the connector to the engine ecu, possible water ingress.

 

Would that be the ecu within the tddi pump, or the unit near the driver pedal box ?

 

Do you have the exact diagnostic messages? Or there numbers?

 

Hi,

The message is DTC 9138 = low battery voltage. As I say, the battery and alternator seem OK whenever I measure the volts nso this must be some kind of intermittent event.

Cleared memory a few times, but this message returns after a while.

terrya

 

Don't recognize this as an engine fault. I think this is a dashboard fault.
How did you obtain this DTC?

 

Got similar problem. battery voltage measured directly is ~13.8V (engine on), regardless off batt. load (lights, defrost etc). But on dash (in test mode) batt. volatge is lower ~13.6V and now the funny part - when i turn on headlight it drops to 12.9-13.0V and engine stalls. I turned on all electrical systems (but no lights) and it was still 13.6V on my dash.
Measuring volts on battery it was at all time 13.8V (headlights on, etc).
Looks like ECU connection problem, but why does it occure just with the headlights on? Current flow is also OK 4.2Amp = ~55W per one bulb.

mondeo 2002 mk3 2.0 petrol

 

I think you are on the right track. I believe the voltage sensor/regulator logic is within the ECU.

After my intermittent problems, my ECU failed completely and due to repair costs vs car value, the car went the to scrapyard.