TORQUE CONVERTER CLUTCH (TCC) CONTROL COMPONENTS
Note. PCM may also be referred to as ECM.
The following components are used in TCC system. Not all components will be present on all vehicles.
DTC 39, TORQUE CONVERTER CLUTCH STUCK OFF (1993)
The purpose of the automatic transmission Torque Converter Clutch (TCC) feature is to eliminate power loss of the torque converter stage when vehicle is in a cruise condition. This allows the convenience of the automatic transmission, and fuel economy of a manual transmission. Fused battery ignition voltage is supplied to the TCC solenoid, which is used inside the valve body to shift a spool valve to modulate pressure to the TCC. This modulated pressure normally allows some slight slippage of TCC.
The PCM/TCM will engage TCC by grounding circuit No. 422, energizing the solenoid. DTC 39 will set under the following conditions; TCC is engaged, TCC "slip" is greater than 65 RPM for 2 seconds or 2nd or 3rd gear is selected or indicated.
Note. Test numbers refer to test numbers on diagnostic chart.
Test Number 1) This step determines if transmission is receiving a TCC command from the pass-thru connector. If bidirectional scan tool is not available, TCC may be activated by grounding ALDL test terminal "B" with ignition on and engine off.
Test Number 2) This step checks for power to transmission.
Test Number 3) This test determines if PCM/TCM is commanding TCC to be on.
DTC 39, TORQUE CONVERTER CLUTCH STUCK OFF (1994)
The purpose of the automatic transmission Torque Converter Clutch (TCC) feature is to eliminate power loss of the torque converter stage when vehicle is in a cruise condition. This allows the convenience of the automatic transmission, and fuel economy of a manual transmission.
PCM/TCM commands the TCC PWM solenoid on by modulating TCC signal fluid acting on converter clutch shift valve. TCC fluid applies torque converter clutch.
DTC 39 will set when DTC(s) 28, 71 or 74 is not present, TCC is commanded on, TCC slip speed is greater than 65 RPM, transmission range switch indicates "D3" or "D4", transmission is in 2nd or 3rd gear and all conditions are met for 2 seconds. PCM/TCM will inhibit 4th gear if in hot mode.
Note. Test number refers to number on diagnostic chart.
Test Number 1) This test checks the mechanical and hydraulic operation of TCC, while commanded on by PCM/TCM.
DTC 69, TORQUE CONVERTER CLUTCH (TCC) STUCK ON (1994)
The purpose of the automatic transmission Torque Converter Clutch (TCC) feature is to eliminate power loss of the torque converter stage when vehicle is in a cruise condition. This allows the convenience of the automatic transmission, and fuel economy of a manual transmission.
PCM/TCM commands the TCC PWM solenoid on by modulating TCC signal fluid acting on converter clutch shift valve. TCC fluid applies torque converter clutch.
DTC 69 will set when DTC(s) 21, 22, 28, 71 or 74 is not present, TCC is commanded off, TCC slip speed is between -5 and 10 RPM, TPS signal is greater than 25 percent, transmission range switch indicates "D3" or "D4", transmission is in 2nd or 3rd gear and all conditions are met for 2 seconds.
Note. Test number refers to number on diagnostic chart.
Test Number 1) This test checks mechanical state of TCC. When PCM/TCM commands TCC solenoid off, TCC slip speed should increase.
TORQUE CONVERTER CLUTCH (TCC) CIRCUIT CHECK (1993)
The automatic transmission TCC eliminates power loss of torque converter stage when vehicle is in a cruise condition. This allows the convenience of an automatic transmission and fuel economy of a manual transmission.
Fused battery ignition is supplied to TCC solenoid, located inside valve body, to shift a spool valve in order to modulate pressure to TCC. PCM/TCM engages TCC by grounding circuit No. 422 to energize solenoid.
TCC will engage under following conditions: vehicle speed is greater than 30 MPH, transmission is in 4th gear, engine and transmission are at normal operation temperatures, brake switch is closed, throttle position switch signal is steady, and no codes are stored.
Note. Test numbers refer to numbers on diagnostic chart.
Test Number 1) This test checks TCC solenoid and circuits inside transmission for shorts.
Test Number 2) This test verifies power supply to TCC solenoid.
Test Number 3) This test checks for short to ground in circuit No. 422.
Test Number 4) This test checks for PCM/TCM control of TCC. If bidirectional scan tool is not available, TCC may be activated by grounding ALDL test terminal "B" with ignition on and engine off.