DTC 90

DTC 90:

Trans Fluid Temp Circuit Wiring Schematic:

CIRCUIT DESCRIPTION
The purpose of the Torque Converter Clutch (TCC) feature is to eliminate the power loss of the torque converter when the vehicle is in a steady cruise condition. The heart of the system is two Powertrain Control Module (PCM) controlled solenoids located inside the transaxle.

The PCM can determine if the TCC has become engaged when the TCC has not been commanded "ON," or stuck "ON" when it should be "OFF."

DIAGNOSTIC TROUBLE CODE (DTC) 90 WILL SET WHEN
No DTC 21, 22, 24, 72 or 82 is set. Throttle angle is greater than 30%, trans temp is between 40°C (104°F) and 100°C (212°F), trans range switch indicates "D4" or "D3", transaxle is not in 1st gear, TCC is commanded "OFF," and TCC slip speed is between -10 and 40 RPM for 10 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
4th gear will become disabled. The Malfunction Indicator Lamp (MIL) will not become illuminated.

DTC 90 WILL CLEAR WHEN
A current DTC 90 will clear after each ignition key cycle. A History DTC 90 will clear after 50 consecutive ignition key cycles without a current DTC 90 being stored.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks for circuit continuity of the TCC apply solenoid.
2. This checks for an open in the power feed Circuit (CKT) 39.
3. This test checks the Pulse Width Modulator (PWM) return circuitry to the PCM.

DIAGNOSTIC AIDS
The Tech 1 indicates when the PCM has commanded the TCC apply solenoid or PWM solenoid driver "ON" or "OFF." This does not however confirm that the TCC apply or PWM is "ON" or "OFF." To determine if TCC is functioning properly, road test the vehicle. Engine RPM should decrease when the Tech 1 (or equivalent scan tool) indicates that all electrical circuits and components are OK.