Engine Controls - Tests W/codes - Transmission: Specifications Chevrolet Pickup K1500

CODE 69, TORQUE CONVERTER CLUTCH STUCK ON

The TCC solenoid is a normally open exhaust valve. The PCM will engage the solenoid by grounding circuit No. 422 with an internal quad-driver. The PCM continually monitors voltage on TCC circuit for either low or high voltage, depending on the commanded state of the circuit. Code 69 will set under the following conditions.

1. TCC slip is greater than -20, but less than 20.
2. Without TCC locked.
3. TPS is more than 25 percent.
4. Conditions are met for 4 seconds.

When code is set, TCC is on in all gears.

Note. Test numbers refer to numbers on diagnostic chart.

1. This test checks TCC solenoid and the internal transmission harness for short circuits.
2. This test checks for power, from the ignition through the fuse, to the TCC solenoid.
3. This test ensures circuit No. 422 is not shorted to ground.
4. This test checks ability of PCM to ground or control TCC solenoid.

TORQUE CONVERTER CLUTCH (TCC) SOLENOID CIRCUIT CHECK

TCC solenoid is a normally open exhaust valve. PCM engages solenoid by grounding circuit No. 422 with an internal quad-driver. PCM continually monitors voltage on TCC circuit for either low or high voltage, depending on commanded state of circuit. A code will set if a fault is detected.

For example, if PCM commands TCC solenoid on, voltage on that circuit should drop when solenoid is grounded. If voltage stays up for 2 seconds, a code will set. If solenoid is off, voltage on that circuit should remain high. If voltage drops for 2 seconds, a code will set.

Note. Test numbers refer to numbers on diagnostic chart.

1. This test check TCC solenoid and internal transmission harness for short circuits.
2. This test checks for power, from the ignition through the fuse, to the TCC solenoid.
3. This test ensures circuit No. 422 is not shorted to ground.
4. This test checks ability of PCM to ground or control TCC solenoid.

CODE 39, TORQUE CONVERTER CLUTCH STUCK OFF

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.

Code 39 will set under the following conditions.

1. TCC is engaged.
2. TCC "slip" is greater than 65 RPM for 2 seconds.
3. 2nd or 3rd gear is selected or indicated. NOTE: Test numbers refer to numbers on diagnostic chart.

1. This test determines if transmission is receiving a TCC command from the pass-thru connector. If bidirectional scan tester is not available, TCC may be activated by grounding ALDL test terminal "B" with ignition on and engine off.
2. This test checks for power to transmission.
3. This test determines if PCM/TCM is commanding TCC to be on.

TORQUE CONVERTER CLUTCH (TCC) CIRCUIT CHECK

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 the following conditions.

1. Vehicle speed is greater than 30 MPH.
2. Engine at normal operating temperature greater than 149°F (65°C).
3. Transmission at normal operating temperature of 195°F (91°C).
4. Throttle position sensor output is not changing, indicating a steady road speed.
5. Brake switch is closed.
6. 4th gear is indicated.
7. No codes are stored. NOTE: Test numbers refer to numbers on diagnostic chart.

1. This step checks for a shorted internal transmission harness or TCC solenoid.
2. This step verifies power supply to the TCC solenoid.
3. This step checks circuit No. 422 for a short to ground.
4. This step checks PCM/TCM's ability to control the TCC solenoid. If bidirectional scan tester is not available, TCC may be activated by grounding ALDL test terminal "B" with ignition on and engine off.