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Author Topic: Ford Galaxy - Accelerator Pedal Removal & Cleaning (Fault Code: 00777 / 18047)  (Read 14686 times)

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Offline Mirez

  • Pondering the next mod...
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  • Model: Galaxy Mk2
  • Spec: 03 115PS Ghia
  • First Name: Mark
  • Region: South West
  • Country: United Kingdom
Ford Galaxy - Accelerator Pedal Removal & Cleaning (Fault Code: 00777 / 18047)
« on: September 06, 2013, 10:25:36 PM »
« Last Rated on: March 06, 2017, 09:54:48 AM »
The accelerator pedal has two sensors (G79) and (G185) which both measure the position of the pedal. G79 is used by the ECU to determine the throttle request from the driver and G185 is used to verify the G79 signal.

So the ECU is constantly referencing and comparing the two values which should be close, or exactly the same. The purpose is purely a safety issue so the ECU knows the throttle request is genuine. If the value's are significantly different then the ECU will limit the performance (Limp Home Mode) and the fault code "00777 - Accelerator Position Sensor (G79 ) - Implausible Signal" or "18047 - Accelerator Position Sensor 1/2 (G79/G185): Implausible Signal" will be logged. Normally the engine management light will also be illuminated.

Using VCDS we can monitor both sensors and graph them to see what the problem is:


Here we can clearly see the problem, the second sensor isn't reading above 80% on the first acceleration test and on the second drops back to near 0% when it reaches 70%.

The sensors are both in the same unit, mounted on the throttle pedal itself. Removal is strait forward, simply remove the 3 8mm bolts that hold it to the firewall, disconnect the wiring and withdraw from the car:


To access the sensor arms and plate you now need to remove the 4 phillips screws, don't remove the 5th screw just yet!


The 5th screw is a locating/alignment screw. The cover plate you are removing is aligned so before undoing this final screw make some alignment marks around the outside of the case and photograph the cover before removing this screw:


With the cover plate removed you can now see the wiper arms and, on the back of the plate, the varistor tracks. Clean the surface points of the arm's and plate with a contact cleaner before reassembling ensuring the plate it realigned.


With the sensor rebuilt and reinstalled we can use VCDS again to measure the two sensors. Note this time they follow each other much closer and the second sensor now reads the full 100% again.


03 Ford Galaxy 1.9 TDI 115 Ghia in Spruce Green Metallic
With cream leather interior, Full Bodykit, Remapped at 145bhp, Lowered on 18's
08 Ford Transit 2.2 TDI 115 in Frozen White
With retrofitted everything except another slidey door! :)

VCDS HEX/CAN - Scans/Coding done in Wiltshire in exchange for winegums! :)



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