Implausible Electronic Gear Select Signal Received
Table of contents
U1420 RAM Possible Causes
- Faulty Electronic Shift Module (ESM)
- Electronic Shift Module (ESM) harness is open or shorted
- Electronic Shift Module (ESM) circuit poor electrical connection
- Faulty Powertrain Control Module (PCM)
- Faulty Transmission Control Module (TCM)
How do I fix code U1420 RAM?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Cost of diagnosing the U1420 RAM code
The cost of diagnosing the U1420 RAM code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
U1420 RAM Description
This diagnostic checks for the validity and availability of the Shift Lever Position signal which is sent by the Electronic Shift Module (ESM) via a CAN message. A CAN signal state is defined for each of five stable lever positions: ‘Park’, ‘Reverse’, ‘Neutral’, ‘Drive’ and ‘Autostick’. CAN signal states are defined for six non-stable positions: ‘Up’, ‘Down’, ‘P-R’, ‘R-N’, ‘N-D’ and ‘D-A’. The diagnostic checks the validity by verifying the received CAN signal state corresponds to one of the possible lever positions. The diagnostic also checks the availability by verifying the valid bit. When the Shift Lever Position signal is invalid or missing, then the Diagnostic Trouble Code (DTC) U1420 will set. The failure is detected if at least one of the following malfunctions is verified: 1) Signal Not Available Check: When the signal is not available, the ESM sends an SNA default value. If the TCM reads this value, then DTC U1420 is set. 2) Signal Invalid Value Check: If the signal value is equal to a different value than the defined values for the lever position, the Shift Lever Position value is considered not valid, then DTC U1420 is set.