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Test Mode

  1. This mode can detect the same malfunctions as Normal Mode. Test Mode is more sensitive to intermittent and regular faults. This mode is used for road test conditions.
  2. Turn ignition off. Using a jumper wire, connect terminals TE2 and E1 of TDCL connector. See Figure. Push O/D switch on. Turn ignition on. Ensure CHECK engine light is flashing. A flashing CHECK engine light indicates system is in test mode. DO NOT turn ignition off until all diagnostic codes have displayed. Record diagnostic codes from O/D OFF light.
  3. Turn ignition off. Using a jumper wire, connect terminals TE1 and E1 of TDCL connector. See Figure. DO NOT disconnect jumper wire connecting TE2 and E1. Turn ignition on.
  4. Ensure diagnostic Code 68 is output. Depress accelerator pedal all the way down, until kickdown switch is activated. Ensure O/D OFF light changes from showing a Code 68 to a normal blinking pattern. If Code 68 is not output or if O/D OFF light does not change to a normal blinking pattern, the kickdown switch circuit may be malfunctioning.
  5. Refer to LS400 AUTOMATIC TRANSMISSION CODE IDENTIFICATION table. Refer to appropriate transmission diagnostic chart. For location of transmission components, see Fig 1.
  6. To check voltage of TPS, brake signal and shift position signal, remove jumper wire from TDCL connector. Using a DVOM, connect positive lead to terminal Tt and negative lead to terminal E1 of TDCL connector.
    NOTE: If a DVOM with a small internal resistance is used, an incorrect voltage reading will be obtained. Use a DVOM with an internal resistance of at least 10 k/ohms.
  7. Turn ignition on. Depress accelerator pedal and observe TPS voltage change from approximately 0-8 volts. Open throttle valve fully. Depress brake pedal.
  8. With brake pedal depressed, voltage should be approximately zero volts. With brake pedal released, voltage should be approximately 8 volts. Start engine.
  9. With engine running and vehicle speed more than 6 MPH, place gear position selector in each position indicated in LS400 GEAR SHIFT POSITION table. Voltage output should be close to voltage shown in table. To clear codes, see CLEARING CODES in this article.
LS400 GEAR SHIFT POSITION

Gear Position Approximate Voltage
1st Gear 0
2nd Gear 2
3rd Gear 4
3rd Lock-Up 5
O/D 6
O/D Lock-Up 7
Fig 1: Locating Transmission Components (LS400)
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