Faulty or intermittent wheel speed sensor or its wiring, feeding bad speed data to the ABS module; Damaged wiring, corroded or loose connectors in the speed sensor or CAN network circuits; Brake pedal switch or brake data signal fault (switch out of adjustment, faulty or wiring problem); Low battery voltage or poor earths causing modules to drop messages; Fault in the ABS module or the module that supplies the speed message; Faulty PCM or outdated PCM software where a known fault is documented for the model.

P1502

Invalid or Missing Vehicle Speed Message or Brake Data.

Lincoln
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
5: AreaVehicle speed, idle control and auxiliary inputs
02: FaultThe specific fault in that area

What it means

On a Lincoln, P1502 means the powertrain control module has received an invalid, implausible or missing vehicle speed message or brake data from another module over the vehicle network. The PCM relies on this information for idle control, torque management and cruise control, so when the signal drops out or disagrees with other inputs it stores the code. The exact source module and message vary by model and year.

Symptoms

Engine management or check engine light on
Cruise control not working or cutting out
Erratic or unstable idle, especially when slowing or stopping
Speedometer or other instrument cluster readings behaving oddly
ABS or traction control warning lights on at the same time
Occasional rough shifting or changed transmission behaviour

Possible causes

Faulty or intermittent wheel speed sensor or its wiring, feeding bad speed data to the ABS modulelikely
Damaged wiring, corroded or loose connectors in the speed sensor or CAN network circuitslikely
Brake pedal switch or brake data signal fault (switch out of adjustment, faulty or wiring problem)possible
Low battery voltage or poor earths causing modules to drop messagespossible
Fault in the ABS module or the module that supplies the speed messagepossible
Faulty PCM or outdated PCM software where a known fault is documented for the modelrare

How to diagnose

Read all stored codes from every module and note any ABS, network communication or wheel speed codes alongside P1502
Review freeze frame data to see road speed, engine load and conditions when the code was set
Check battery condition and charging voltage, and inspect the main earth connections
Compare live vehicle speed in the PCM with the ABS wheel speed readings on a road test or with the wheels spinning safely
Check brake switch operation and live brake status data against pedal movement
Inspect wheel speed sensor wiring, connectors and tone rings for damage, corrosion or debris
Test the network wiring for continuity, shorts and correct resistance following the model's wiring diagram
Check for manufacturer service bulletins or software updates relevant to the model and engine

How to fix

Repair or replace faulty wheel speed sensors or damaged tone rings
Repair damaged wiring and clean or replace corroded connectors
Replace or correctly adjust the brake pedal switch
Restore battery condition and repair poor earths or charging faults
Repair or replace the faulty ABS or speed signal module once the wiring is proven good
Update the PCM software only if a documented fault for that model calls for it

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but get it checked soon as cruise control and idle quality may be affected. If the ABS or brake warning lights are also on, braking assistance may be reduced, so have it inspected promptly.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.