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Automatic Transmission External Controls Pinpoint Test 3: The Transmission Control Switch (Over-Drive Od, On/Off) Is Not Operating Properly

TRANSMISSION CONTROL SWITCH (OVERDRIVE ON/OFF) IS NOT OPERATING PROPERLY - PINPOINT TEST REFERENCE

PINPOINT TEST 3 TRANSMISSION CONTROL SWITCH (OVERDRIVE ON/OFF) IS NOT OPERATING PROPERLY
STEP INSPECTION ACTION
1 CHECK SMART JUNCTION BOX (SJB) FUSE 20(10A)
  • Key OFF.
  • Measure resistance of SJB fuse 20 (10A).
  • Is the resistance less than 5 ohms?
 Yes Reinstall the fuse. Go to step 3.
No Replace the failed fuse. Test the system for normal operation. If the fuse fails again, Go to step 2.
2 CHECK CIRCUIT (BR/G) FOR SHORT TO GROUND
  • Disconnect powertrain control module (PCM).
  • Inspect for damaged or pushed out pins, corrosion and loose wires. Repair as necessary.
  • Leave the PCM disconnected.
  • Install 104-pin breakout box.
  • Measure the resistance between test pin 29 and test pins 24 and 77 at the 104-pin breakout box.
  • Is the resistance greater than 10,000 ohms? 
 Yes Check circuit (BR/G) and related components for a short to ground. Test the system for normal operation.
No Repair circuit (BR/G). Test the system for normal operation.
3 CHECK TRANSMISSION CONTROL SWITCH (TCS) CIRCUIT FOR VOLTAGE
  • Disconnect PCM.
  • Inspect for damaged or pushed out pins, corrosion and loose wires. Repair as necessary.
  • Leave PCM disconnected.
  • Install 104-pin breakout box.
  • Key ON.
  • Measure the voltage between test pin 29 and test pins 24 and 77 at the 104-pin breakout box while cycling the TCS switch several times.
  • Does the voltage cycle? 
 Yes Replace the PCM.
See POWERTRAIN CONTROL MODULE (PCM) REMOVAL / INSTALLATION , . Remove the 104-pin breakout box. Test the system for normal operation.
No Go to step 4.
4 CHECK CIRCUITS (Y/V) AND (BR/G) FOR AN OPEN
  • Key OFF.
  • Disconnect SJB fuse 20 (10A).
  • Disconnect transmission control switch (TCS).
  • Inspect both ends for damaged or pushed out pins, moisture, corrosion and loose wires. Repair as necessary.
  • Measure the resistance between the SJB Fuse 20 (10A) connector pin 1 and the power side of the TCS vehicle harness connector (Y/V) wire.
  • Measure the resistance between test pin 29 at the 104-pin breakout box and signal side of the transmission control switch vehicle harness connector circuit (BR/G).
  • Is the resistance less than 5 ohms for both circuits? 
 Yes Go to step 5.
No Repair the open circuit. Remove 104-pin breakout box. Reconnect all components. Test the system for normal operation.
5 CHECK CIRCUIT (BR/G) FOR SHORT TO POWER
  • Measure the resistance between test pin 29 and test pins 71 and 97 at the 104-pin breakout box.
  • Is the resistance greater than 10,000 ohms? 
 Yes Replace the transmission control switch. See TRANSMISSION CONTROL SWITCH (TCS) REMOVAL / INSTALLATION . Remove the 104-pin breakout box. Reconnect all components. Test the system for normal operation.
No Repair circuit (BR/G). Remove the 104-pin breakout box. Reconnect all components. Test the system for normal operation.
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