Analog PRND shifter (legacy)

Overview

When the car has an old-style analog shifter with a cable that originally actuated the manual valve of the transmission, the cable can be replaced with a linear position sensor connected to the device. With this arrangement the transmission mode is switched electronically, and the mode-selection triggers come from the original shifter lever. Shifters of this style often combine the cable with microswitches that are used to select manual mode and to signal upshift and downshift requests.

Prerequisites

  • A linear position sensor attached to the shifter in place of the original cable. The sensor must be connected to the device signal ground, an analog input and the 5 V sensor supply.
  • If applicable, the shifter's internal microswitches connected to analog inputs. The active signal should be 5 V.

Input configuration

Each shifter position should have its own Analog Switch Input reading the linear sensor, configured as follows:

Setting Value
Range 5V
Mode Voltage
Enable filter On
Delay 200 ms
Hold 100 ms

For each position there is a voltage window in which the device registers the input:

Input Nominal voltage Voltage min Voltage max
Parking 0.5 V 0.4 V 0.6 V
Reverse 1.3 V 1.2 V 1.4 V
Neutral 1.8 V 1.7 V 1.9 V
Drive 2.4 V 2.3 V 2.5 V

Please note that the values here are just examples — obtain the real ones by logging and measuring the sensor voltage in each position. The voltage windows must not overlap.

The filter Delay matters with this shifter: when the lever moves from Parking to Drive, the sensor passes through the Reverse and Neutral windows on the way. With the filter enabled, a window only triggers once the lever rests in it for the Delay time, so positions the lever merely passes through do not fire.

When measuring the sensor voltages, make sure the readings stay consistent regardless of movement direction, shifter play and other factors. The device acts on whatever input triggers — including triggers caused by a faulty or drifting signal. Please configure the mode-change safety conditions (safety map) so an invalid reading cannot cause an unexpected mode change.

The manual-mode and upshift/downshift microswitches are set up the same way — one Analog Switch Input per switch, each on its own pin. Since the active signal is 5 V, use a voltage window in the upper part of the range (for example 4.0–5.0 V), with the filter enabled to debounce the contacts.

Mode configuration

The device uses a state-machine table that lets you define how the modes change on activation of each assigned input. Modes are represented by columns, each row represents an input trigger, and each cell holds the new mode that is engaged when that input triggers in that mode:

Input Reverse Parking Neutral Drive Manual Sport
Parking Parking Parking Parking Parking Parking Parking
Reverse Reverse Reverse Reverse Reverse Reverse Reverse
Neutral Neutral Neutral Neutral Neutral Neutral Neutral
Drive Drive Drive Drive Drive Drive Drive
Manual Manual Manual Manual Manual Manual Manual
Upshift Reverse Parking Neutral Drive Manual Sport
Downshift Reverse Parking Neutral Drive Manual Sport
Other Reverse Parking Neutral Drive Manual Sport

How it works

When the shifter is moved, each position input triggers once the sensor settles in its configured voltage window. In this configuration each position input switches directly to its respective mode, regardless of the currently active mode — the lever position is the single source of truth, exactly as with the original mechanical linkage.

The Upshift and Downshift rows leave the mode unchanged — in Manual mode these triggers request gear changes rather than mode changes. The Sport column is shown for completeness; none of the inputs configured here enters it. To use it, add a transition (or an additional input) that leads into it.

Troubleshooting

  • A mode engages briefly while shifting through it: the filter Delay is too short — increase it so pass-through positions do not trigger.
  • A position is not recognised: the sensor voltage is outside the configured window — re-measure the voltage in that position and adjust the window.
  • The mode flickers between two positions: the windows are too close together or the signal is noisy — widen the gap between windows and check the sensor wiring and ground.

Remarks

This is an example configuration. It is intended to showcase how the device works and how to set up the mode transitions. If desired, this configuration can be extended or modified to fit more complex scenarios.