|Trouble Code||Fault Location||Probable Cause|
|U1417||Implausible Left Wheel Distance Signal (Dodge, Chrysler, Jeep)||Wiring, Defective wheel sensor, Wheel speed sensor / reluctor ring, Wheel size, Deflated wheel, PCM|
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What Does Code U1417 Mean?
OBD II fault code U1417 is a manufacturer specific code that is defined by car makers Dodge, Chrysler, and Jeep as “Implausible Left Front Wheel Distance Signal”, or sometimes as “Implausible Left Front Wheel Distance Signal Received”, and is set when the PCM (Powertrain Control Module) detects an inaccurate, implausible, erratic, or corrupted signal from the left front wheel speed sensor.
Although wheel speed sensors have the primary function of supplying the ABS control module with information regarding the rotational speed of each individual wheel, these sensors also perform several other functions. In terms of the ABS system, the wheel speed sensors monitor the rotational speed of each wheel to prevent the brakes locking up under severe braking, and especially during severe braking on slippery surfaces. In practice, the ABS control module compares the rotational speeds of the wheels, and when it detects that one or more wheels are rotating more slowly than the other wheels during braking, it will momentarily (and repeatedly) release the brake pressure on those wheels until all wheels again rotate at the same speed.
However, other systems like traction control, stability control, hill descent, and others also use primary input data from the wheel speed sensors in order to maintain, or restore the vehicle’s stability through selective brake applications via the ABS system during sudden or violent direction changes. In these cases, the algorithms that control the ABS system requires both the rotational speed of the wheels, and the distance that each wheel covers during a full wheel rotation, the latter being a function of the wheel diameter.
This data is compared to data obtained from the steering angle sensor and others such as yaw rate sensors, which is in turn compared to the distance that each wheel covers during a full rotation. This comparison has two objectives; the first being to verify that all the wheels are rotating, and that even though all wheels are rotating, all wheels cover a distance that is equal to their circumference as a means to identify potentially dangerous situations, such as a slide or skid.
During the normal course of events though, i.e., during normal vehicle operation, the distance each wheel covers during a full rotation is monitored continually, regardless of the wheels’ rotational speeds both as a means to verify the integrity of input data from each wheel sensor, and to monitor the stability of the vehicle. Thus, when the PCM and/or the ABS control module detects an implausible signal from, in this case, the left front wheel sensor, it concludes either that the wheel is covering a bigger or smaller distance than it should, or that the wheel sensor is generating inaccurate data about the rotational speed of the wheel.
Regardless of the actual cause of the inaccurate or implausible data, the PCM and ABS brake module will both recognize that they cannot maintain or restore the vehicles’ stability during violent directional changes or severe braking conditions. As a result of this, either the PCM or the ABS control module (depending on the vehicle) will set code U1417 and illuminate one or more warning lights- typically the ABS and/or traction/stability control warning lights. Note though that in most instances of code U1417, the PCM will also deactivate the stability and traction control systems, and sometimes the cruise control and ABS systems as well as a safety precaution, although normal brake operation will still be available.
Where is the U1417 sensor located?
The image above shows the typical location of a wheel sensor relative to the drive shaft and brake system.
Note the “teeth” on the reluctor ring; during normal operation, the teeth each create a small magnetic field when they pass in front of the sensor. This field is converted into an electrical current, and the resulting number of “ON” pulses thus created is counted by various control modules, and then converted into the rotational speed of the wheel, based on the frequency of the “ON” pulses. In the later case, the distance the wheel covers is a function of the number of teeth on the reluctor ring, which means that the distance a wheel covers during a full rotation can be monitored independently of the wheels’ rotational speed.
What are the common causes of code U1417?
Some common causes of this code could include one or more of the following-
- Damaged, burnt, disconnected, shorted, and/or corroded wiring in the affected wheel speed sensors’ wiring harness
- Defective wheel sensor
- Defective or damaged wheel speed sensor and/or reluctor ring as the result if impacts by road debris. Note that while this is rare, it does happen.
- Use of some aftermarket replacement sensors
- Different wheel size on the affected wheel. Note that if a different wheel size is used in an emergency, several safety or driver assist systems may be deactivated
- On some vehicles with permanent AWD systems, a partially deflated wheel will sometimes be interpreted by the PCM as a defective wheel speed sensor
- Failed or failing PCM, but note that since this a rare event, the fault must be sought elsewhere before any control module is replaced
What are the symptoms of code U1417?
Common symptoms of code U1417 could include the following-
- One or more warning lights may be illuminated
- Cruise control, or other driver assist systems such as stability and traction control may be deactivated
- Hill Descent system may be deactivated
- ABS functionality may not be available
- If fitted, selectable electronic AWD may not be available
- If fitted, Electronic Brake Distribution may not be available
Note that as a general rule, most, or all driver assist systems that use the ABS system to function may be disabled or deactivated automatically by either the PCM or the ABS control module when codes such as U1417 or other ABS related codes are present