SureTrack Real Fix: Transmission Faults

When your customer brings their car in with the check engine light on, one of the last things they want to hear is that they have transmission faults. Follow this Real Fix to see how codes P0720, P0731, P0732 and P1790 on this 2002 Chrysler Voyager were diagnosed and the component that caused the problem.

Vehicle
2002 Chrysler Voyager 3.3L

Title
P0720, P0731, P0732, P1790, Replaced Automatic Transmission Control Module

Complaint
The customer states the check engine light is on.

Cause
Connected a scan tool and found codes: P0720 – Output Speed Sensor Circuit; P0731 – Gear 1 Incorrect Ratio and P0732 – Gear 2 Incorrect Ratio and P1790 – Fault Immediatly After Shift. Performed a road test while monitoring live scan tool data and observed the tranmission output shaft speed sensor parameter was not present. With the ignition on and the engine off, used a multi-meter to check for the presence of voltage and ground at the transmission output shaft speed sensor connector and found voltage was not present. Inspected the transmission output shaft speed sensor wiring harness and connector and detected no obvious faults. With the ignition on and the engine off, used the multi-meter to check for the presence of voltage at the transmission output shaft speed sensor supply terminal on the automatic transmission control module and found voltage was not present. With the ignition on and the engine off, used the multi-meter to check for the presence of voltage and ground at the automatic transmission control module connector and found both were present. Disconnected the automatic transmission control module connector, inspected the connector terminals and found no faults. The results of these tests verified the automatic transmission control module was faulty.

Correction
Replaced the automatic transmission control module, cleared codes, performed a road test and verified the vehicle operated properly. The check engine light did not illuminate and no fault codes returned.