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Test G - Throttle Position Sensor (TPS)

  1. Code 23 (from Key On-Engine Off Self-Test). If code 68 is present, go to TEST H. If no code 68, proceed with test. Before continuing with test, lightly press throttle lever toward actuator tip of idle speed motor while performing KEY ON-ENGINE OFF (KOEO) SELF-TEST  . If code 23, go to step  3 . If no code 23, TPS is a little out of adjustment. DO NOT  adjust TPS, EEC system is operating properly.
  2. Code 23 (from Key On-Engine Running Self-Test). If code 58 is present, go to TEST H  . If no code 58, proceed with test. Before continuing with test, check for code 31 and/or 41 after performing KEY ON-ENGINE RUNNING (KOER) SELF-TEST  . If code 31, go to TEST I  . If code 41, go to TEST J  . If no code 31 and/or 41, go to next step.
  3. Inspect carburetor and throttle linkage for binding. Check that throttle linkage is at mechanical closed throttle. Check for binding speed control linkage and vacuum line or electrical harness interference. If throttle is not stuck, go to next step. If stuck, repair as required and repeat QUICK TEST  .
  4. Turn ignition off and wait 10 seconds. Disconnect TPS and inspect for damaged pins, corrosion, and loose wires. Repair as required. Perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  and record codes. If code 63, replace TPS and repeat QUICK TEST  . If no code 63, replace ECA and repeat QUICK TEST  .
  5. Code 53. Turn ignition off and wait 10 seconds. Disconnect TPS and inspect. With DVOM on 20 volt scale, connect test leads to battery positive terminal and signal return circuit of TPS harness. If voltage is 10 volts or more, go to next step. If less than 10 volts, go to step  8 .
  6. Ignition off, TPS disconnected and DVOM on 20 volt scale. Connect test leads to TPS harness between throttle position signal circuit and signal return circuit. Turn ignition on and note voltage. If less than 4 volts, go to next step. If 4 volts or more, go to step  9 .
  7. Turn ignition off and wait 10 seconds. With TPS disconnected, perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  . If code 63 appears, replace TPS and repeat QUICK TEST  . If no code 63, replace ECA and repeat QUICK TEST  .
  8. Turn ignition off and wait 10 seconds. With TPS disconnected, set DVOM on 200 ohm scale. Disconnect 60-pin connector at ECA and inspect for damage. Connect breakout box and leave ECA disconnected. Check continuity of TPS harness between signal return circuit and box pin 46. If less than 5 ohms, replace ECA and repeat QUICK TEST  . If 5 ohms or more, repair open circuit and repeat QUICK TEST  .
  9. Turn ignition off and wait 10 seconds. With same connections as in step  8 , set DVOM on 200,000 ohm scale. Measure resistance between box pin 47 to pins 26 and 57. If either is less than 10,000 ohms, repair short in harness and repeat QUICK TEST  . If both 10,000 ohms or more, replace ECA and repeat QUICK TEST  .
  10. Code 63. ECA connected and breakout box disconnected. Turn ignition off and wait 10 seconds. Disconnect TPS and inspect. Place DVOM on 20 volt scale. Turn ignition on. Measure voltage of TPS harness from voltage reference circuit to throttle position circuit. If reading is 4-6 volts, go to next step. If less than 4 volts, go to step  13 . If 6 volts or more, go to TEST C  .
  11. Turn ignition off and wait 10 seconds. TPS disconnected. Disconnect 60-pin connector at ECA, inspect and repair as required. With DVOM on 200,000 ohm scale, connect 1 lead to throttle position signal circuit of TPS harness and other lead to ground. If reading less than 10,000 ohms, repair short circuit and repeat QUICK TEST  . If 10,000 ohms or more, go to next step.
  12. Turn ignition off and wait 10 seconds. TPS disconnected. Insert jumper wire into TPS harness between voltage reference circuit and throttle position signal circuit. Perform KEY ON-ENGINE OFF (KOEO) SELF-TEST  . If code 53, replace throttle position sensor and repeat QUICK TEST  . If no code 53, replace ECA.
  13. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect. Connect breakout box and connect ECA to breakout box (TPS disconnected). With DVOM on 200 ohm scale, measure continuity of TPS harness from throttle position signal circuit to box pin 47 and from voltage reference signal circuit to box pin 26. If either is 5 ohms or more, repair circuit, reconnect TPS, remove breakout box and repeat QUICK TEST  . If less than 5 ohms, replace ECA, reconnect TPS, remove breakout box and repeat QUICK TEST  .
  14. Code 73. Code 73 indicates sensor did not exceed 25 percent of its rotation during Engine Response Check. Turn ignition off. Connect breakout box (TPS and ECA connected). With DVOM on 20 volt scale, measure voltage between box pins 47 and 46. Perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST  . If DVOM exceeds 3.5 volts during wide open throttle of Engine Response Check, replace ECA and repeat QUICK TEST  . If less than 3.5 volts, verify TPS is properly mounted. If mounting is okay, replace TPS and repeat QUICK TEST  .
  15. Continuous code 53. Using CONTINUOUS MONITOR TEST  mode, observe volt/ohmmeter for fault indication while doing the following: Move throttle slowly to wide open position. Slowly release throttle to closed position and lightly tap on TPS to simulate road shock. Wiggle TPS harness connector. If a fault is indicated, go to next step. If no fault indicated, go to step  19 .
  16. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect. Connect breakout box and reconnect ECA. With DVOM on 20 volt scale, connect leads between box pins 47 and 46. Turn ignition on. While observing DVOM, repeat step 15). If fault is indicated below 4.25 volts, disconnect and inspect harness connectors. If okay, replace TPS and repeat QUICK TEST  . If fault does not occur, TPS overtravel may have caused Continuous Code 53. Sensor service not required. Proceed to next step to verify harness integrity.
  17. Turn ignition off and wait 10 seconds. Remove breakout box, reconnect ECA and TPS. Watch volt/ohmmeter while doing the following: Beginning at TPS, wiggle, shake or bend small sections of harness while working way to dash panel. Then repeating process from panel to ECA. If fault is indicated, isolate and repair problem and repeat QUICK TEST  . If no fault indicated, go to next step.
  18. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect both harness connector and ECA connector for damage or faults. If damaged, repair as required and repeat QUICK TEST  . If no damage or fault, unable to duplicate fault at this time. Continuous Code 53 test complete.
  19. Continuous Monitor Code 63. Using CONTINUOUS MONITOR TEST  mode, observe volt/ohmmeter for fault indication while doing the following: Move throttle slowly to wide open position. Slowly release throttle to closed position and lightly tap on TPS to simulate road shock. Wiggle TPS harness connector. If a fault is indicated, disconnect and inspect harness connectors. If connectors and terminals okay, replace TPS and repeat QUICK TEST  . If no fault indicated, go to next step.
  20. Turn ignition off and wait 10 seconds. Watch volt/ohmmeter while doing the following: Beginning at TPS, wiggle, shake or bend small sections of harness while working way to dash panel. Then repeating process from panel to ECA. If fault is indicated, isolate and repair problem and repeat QUICK TEST  . If no fault indicated, go to next step.
  21. Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect for damage or fault. If terminals and pins are damaged, repair as required and repeat QUICK TEST  . If no damage, fault cannot be duplicated at this time. Continuous Code 63 test complete.
Fig 1: Throttle Position Sensor (TPS) Circuit
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