* Faulty PCM (Powertrain Control Module): The PCM receives the signal from the VSS. If the PCM is malfunctioning, it might not be processing the signal correctly, leading to a speedometer and odometer failure, as well as triggering the check engine and ABS lights. This is a significant possibility given the multiple systems affected.
* Wiring harness issues: Check the wiring harness between the VSS, the ABS module, and the PCM. Look for broken wires, corroded connections, or short circuits. A break in the wiring could interrupt the signal, impacting all affected systems. Pay close attention to the area near the transmission and wheels where the wiring is prone to damage.
* ABS module failure: While you changed the speed sensor, a faulty ABS module could be causing the problem. The ABS module uses the VSS signal, and a malfunction could prevent the signal from reaching the speedometer and PCM correctly.
* Instrument cluster malfunction: Though less likely after addressing the sensor, a faulty instrument cluster could prevent it from displaying the speed signal even if it's being received.
* Grounding issue: Poor electrical grounding can cause erratic readings and malfunctioning systems. Check the ground connections related to the PCM, ABS module, and instrument cluster.
* Incorrect VSS installation: Double-check that the new speed sensor was installed correctly. Even a slightly misaligned sensor can prevent accurate signal transmission.
Troubleshooting Steps:
1. Get diagnostic codes: Use an OBD-II scanner to retrieve diagnostic trouble codes (DTCs) from the PCM. These codes will provide clues about the specific problem.
2. Check wiring: Carefully inspect the wiring harness connecting the VSS to the PCM and ABS module for any damage.
3. Test the VSS signal: Use a multimeter to test the voltage and signal output from the VSS. This requires knowing the correct signal specifications for your vehicle, usually found in a repair manual.
4. Inspect the ABS module: If the wiring checks out, have the ABS module tested to make sure it's functioning correctly.
5. Inspect the instrument cluster: If you have access to a suitable tool or knowledge, test the instrument cluster to make sure it can receive and display the speed signal.
Given the complexity and the multiple systems affected, it's highly recommended to take your Durango to a qualified mechanic or auto electrician for proper diagnosis and repair. Attempting more complex troubleshooting without the proper tools and knowledge could lead to further damage.
