mk6 fiesta big electrical failure

[charlie w]

my mk6 fiesta has had a large failure probably electrical. my car has lost abs, speedo, digital mileage prediction, odometer frozen, boot latch button doesn't work if the car is on but does work if its off, also engine warning light is on but the car runs just as normal and has done for months now, the car is booked in for mot in a couple weeks and i need to fix this issue fast, can anyone help me at all thanks.

[unofix]

Oh we do all enjoy a big electrical failure here, something to get stuck in to 🤣

Several things pop up.

1. Use FORScan on a windows Laptop and get all of the Ford specific DTC's so as to eliminate pure guess work.
2. It could very well be a problem with poor quality solder joints on the instrument cluster.
3. Water ingress to the GEM is also to be considered.
4. The vehicles battery and its State Of Charge needs to be checked.

You quite possibly have more than just one fault, did all of these problems happen at the same time ?

[Paulkp]

Would the failure of the VSS not cause loss of ABS, Odo, and mileage prediction ?  ECU might also be a bit suspect, as inputs and outputs are from that module (See P85, April 2019 Car Mechanics).  The VSS will probably be an ABS Sensor.

26 minutes ago, unofix said:

Use FORScan on a windows Laptop and get all of the Ford specific DTC's so as to eliminate pure guess work.

Agreed, but I only have a code reader for a Sierra ......

[Dan62]

ALL of your symptoms point to the ABS module failing.
Check the ABS module fuses F5  F6 & F37 are good.

[TomsFocus]

11 hours ago, Paulkp said:

Would the failure of the VSS not cause loss of ABS, Odo, and mileage prediction?

Some Mk6's did still use a gearbox mounted VSS.  That would knock out speedo and everything that's run from that (odo, range, boot button) but I'm not sure if it would trigger an ABS warning.  Technically the ABS module only needs speed inputs from the wheel sensors, but it may also use the VSS to compare with those, as it doesn't kick in below about 15mph.

Checking for a gearbox sensor would probably be the first thing I'd do on this car with this fault.