Ford Focus Pats Immobiliser Issue (Solved)

[Grim]

I've recently had some problems with my mk2 focus immobiliser, which i've fixed, so i thought i'd document it for others / random googlers in the future!

 

I first noticed it taking longer to start, cranking fine but just taking time to fire. On cold/frosty mornings it would longer still to start and then the red immobiliser LED on the dash would flash an error code. It flashed quickly for 30s, then flashed once, paused, flashed twice. This related to fault code 12, which is an immobiliser transceiver fault. Ford wanted £120+vat for a new transceiver, so i thought I'd take a look at it myself.

The transceiver is located around the ignition barrel, and reads the code from the chip stored in the key. Access is by removing the top and bottom steering column shroud, and the transceiver can be unclipped from position.

Once removed, the cover can be removed, revealing the circuit board and coil. The pins that the wiring connector and coil were fixed to the circuit board appeared to be pressed into place, and not soldered, which struck me as a potential dirty contact to cause intermittent faults. I soldered these 6 pins (pictured), reassembled, and the fault has not recurred. no problems on the few frosty mornings this week, and cranking time before starting has halved. Fingers crossed that is problem solved!

 

Andy

 

[Grim]

a very good question. I suspect it's cost saving, the boards might be made on one production line / factory and then transferred to another for assembly, without soldering facilities and the setup / time that saves.

[richyb66]

Presumably the sensor coil is soldered to the board? You'd think they'd solder the pins at the same time?

[Grim]

the coil is soldered to 2 of the 6 pins. Presumably the pins are placed in position when the housing is injection moulded, coil is wound and soldered to those 2 pins, then the circuit board fitted afterwards. A weird choice not to solder them.

Edited February 26, 2016 by Grim

[fry61]

Can't beat a drop of flux & a pool of molten metal.

[Jez Morton]

Next week be the connector, they used to be insulation displacement connectors don't know if they still are. Imagine a row of tiny scotch locks?