Ford is issuing a major recall of 552,188 units of the 2014 F-150 pickup truck. The problem concerns a transmission defect that can lead to unexpected downshifts in first gear, while the vehicle is travelling at any speed.
This can be a worrying situation at highway speeds, for example.
The problem
According to Ford's recall report, “some vehicles may experience an intermittent loss of signal from the output shaft speed sensor (OSS) to the powertrain control module (PCM), which could result in a temporary, unintended downshift into first gear.”
This transmission problem can lead to loss of vehicle control or even immobilization. It is attributed to a faulty transmission sensor.
Causes identified
Ford has identified several possible causes for OSS signal problems, including contamination, short circuits, connector corrosion and incorrect OSS sensor outputs. Because of this variety of possible causes, there is no single solution to directly fix the issue.
Whatever the exact cause, the age of the vehicle certainly plays a part, the issue not having manifested itself in the vehicle's early years on the market. We can guess that better-preserved models may be less at risk, but this is only speculation.
Proposed solution
To fix the problem, Ford will update the software governing the shifting function to include a "plausibility check". This check will ensure that the speed indicated by the OSS sensor is consistent before automatically commanding a downshift into first gear.
This software update is designed to prevent unintentional downshifts that could lead to accidents.
Impact
Ford's report does not indicate any irreparable damage to the powertrain as a result of the problem. However, it does mention several incidents where the rear wheels of trucks locked and the driver lost control.
Owners of affected models are advised to await notification from Ford before having their F-150 repaired. These should be sent out from early July.
Those who have already carried out repairs related to this problem outside the warranty coverage period may be eligible for a refund.