Test B8 - TPS

Fig 1: TPS Electrical Circuit

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: idle speed/throttle stop adjustment, binding throttle shaft/linkage or cruise control linkage.

1. Service Code 23. Code 23 indicates that the TPS rotational setting may be out of the Self-Test range. See TPS SPECIFICATION  table. If KOEO SELF-TEST Code 68 or KOER SELF-TEST Codes 31, 41, or 58 are displayed, service these codes first. Disregard Code 23 at this time. If these codes are not displayed, go to next step.
2. Check for Stuck Throttle Plate. Inspect throttle body and linkage for binding or sticking. Ensure linkage is set with throttle in closed position. If throttle plate or linkage is binding, check for binding throttle or cruise control linkage, vacuum line or harness interference, etc. Repair any problem and repeat QUICK TEST. If no mechanical problem is found, go to next step.
3. Service Code 53: Attempt To Generate Code 63. Code 53 indicates that TPS signal is greater than Self-Test maximum value. See TPS SPECIFICATION  table. Possible causes are: faulty TPS, short to power in harness or faulty ECA. Turn key off and wait 10 seconds. Disconnect TPS harness connector at throttle body. Inspect and repair any damaged wiring. Perform KOEO SELF-TEST. Check for Code 63. Ignore all other codes at this time. If Code 63 is not displayed, go to step 5). If Code 63 is displayed, go to next step.
4. Check VREF to Signal Return. Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Disconnect TPS harness connector at throttle body. Inspect and repair any damaged wiring. With KOEO, measure voltage at TPS harness connector between VREF and SIG RTN. See Fig 1 . If reading is not 4-6 volts, go to TEST A3 - REF  . VOLTAGE, step 1). If reading is 4-6 volts, replace TPS, adjust and repeat QUICK TEST.
5. Checking TP Signal For Short to Power. Turn key off and wait 10 seconds. Disconnect TPS. Set DVOM on 200K-ohm scale. Disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Measure resistance between test pin No. 47 and test pins No. 26 and 57 at breakout box. If either reading is less than 10K ohms, repair short in harness. Remove breakout box, reconnect components and repeat QUICK TEST. If both readings are 10K ohms or more, replace ECA. Remove breakout box, reconnect components and repeat QUICK TEST.
6. Service Code 63: Attempt To Generate Code 53. Code 63 indicates that TP signal is less than minimum Self-Test value. Possible causes are: faulty TPS, open harness, grounded harness or faulty ECA. Turn key off and wait 10 seconds. Disconnect TPS harness. Install a jumper wire between VREF and TP at TPS harness connector. See Fig 1 . Perform KOEO SELF-TEST. Check for Codes 53/23. Ignore all other codes at this time. If no codes are displayed, immediately remove jumper wire, and go to step 9). If Code 53/23 is displayed, replace TPS, remove jumper wire, reconnect components and repeat QUICK TEST. If Code 53/23 is not displayed, remove jumper wire and go to next step.
7. Service Code 63: Check Voltage VREF To SIG RTN. Turn key off and wait 10 seconds. Disconnect TPS harness at throttle body. Inspect and repair any damaged wiring. Set DVOM on 20-volt scale. With KOEO, measure voltage between VREF and SIG RTN at TPS harness connector. If reading is not 4-6 volts, go to TEST A3 - REF  . VOLTAGE, step 1). If reading is 4-6 volts, go to next step.
8. Checking TP Circuit Continuity. Turn key off and wait 10 seconds. Leave TPS disconnected. Set DVOM on 200-ohm scale. Disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box and connect ECA to it. Measure resistance between TP signal at TPS harness connector and test pin No. 47 at breakout box. If reading is 5 ohms or more, repair open circuit. Remove breakout box, connect ECA and TPS, and repeat QUICK TEST. If reading is less than 5 ohms, go to next step.
9. Checking Resistance Of TP Circuit To Ground/SIG RTN. Turn key off and wait 10 seconds. Leave TPS disconnected. Disconnect ECA 60-pin connector. Inspect and repair any damaged wiring. Install breakout box and set DVOM on 200K-ohm scale. Measure resistance at TPS harness connector between TP signal and ground. Also measure between TP signal and test pin No. 46 at breakout box. If either reading is less than 10K ohms, repair short circuit, remove breakout box, reconnect components and repeat QUICK TEST. If both readings are 10K ohms or more, replace ECA. Remove breakout box, reconnect components, and repeat QUICK TEST.
   NOTE: Engine Running Service Code 73 in step 10) indicates that TPS did not exceed 25% of its rotation during DYNAMIC RESPONSE ("Goose") CHECK. For additional information see KOER SELF- TEST, DYNAMIC RESPONSE CHECK in this article.
10. Engine Running Service Code 73: TPS Movement During Dynamic Response Test. Turn key off. Disconnect ECA. Inspect and repair any damaged wiring. Install breakout box and connect ECA to it. Set DVOM on 20-volt scale. Connect DVOM to test pins No. 46 and 47 at breakout box. Perform KOER SELF-TEST. If voltage increases to greater than 3.5 volts during Dynamic Response test, remove breakout box, replace ECA and repeat quick test. If voltage does not exceed 3.5 volts, ensure TPS is correctly installed and adjusted. If okay, replace TPS and repeat QUICK TEST.
11. Continuous Memory Code 53: Monitor TP Circuit. Using KOEO CONTINUOUS MONITOR (WIGGLE) TEST. Observe VOM or diagnostic tester for indication of fault while slowly opening throttle to WOT. Slowly release throttle to closed position and lightly tap TPS and wiggle TPS harness connector. If no fault is indicated, go to step 13). If fault is indicated, go to next step.
12. TPS Voltage Measurement. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box and connect ECA to it. Stay in KOEO CONTINUOUS MONITOR (WIGGLE) TEST as in previous step 11). Connect DVOM between test pins No. 47 and 46 at breakout box. Set DVOM on 20 volt scale. Turn key on, leaving engine off. Observe DVOM and repeat step 11). If fault occurs at less than 4.25 volts, inspect TPS connectors and terminals. If okay, replace TPS, clear continuous memory code 53 and repeat QUICK TEST. If fault does not occur at less than 4.25 volts, TPS over-travel may have caused Continuous Code 53. TPS is okay, go to next step to check harness.
13. Checking EEC-IV Harness. While in KOEO CONTINUOUS MONITOR (WIGGLE) TEST, shake, bend and wiggle small sections of EEC-IV harness from TPS to dash panel, and from dash pane to ECA. If fault is indicated, isolate fault in wiring and repair as necessary. Clear continuous memory code 53 and repeat QUICK TEST. If no fault is indicated, go to next step.
14. Checking ECA And Harness Connectors. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connectors and terminals for damage. Repair as necessary. Clear codes and repeat QUICK TEST. If connectors and terminals are okay, fault cannot be duplicated at this time. Clear Continuous Memory Code 53. Testing is complete.
15. Continuous Memory Code 63: Monitor TP Circuit. Enter KOEO CONTINUOUS MONITOR (WIGGLE) TEST. Observe VOM or diagnostic tester for indication of fault while slowly opening throttle to WOT. Slowly bring throttle to closed position and lightly tap TPS and wiggle connector. If fault is indicated, disconnect TPS. Inspect connectors and terminals. If connectors and terminals are okay, replace TPS. Clear continuous memory code 63 and repeat QUICK TEST. If no fault is indicated, go to next step.
16. EEC-IV Harness Test. While in KOEO CONTINUOUS MONITOR (WIGGLE) TEST, shake, bend and wiggle small sections of EEC-IV harness from TPS sensor to dash panel, and from dash panel to ECA. If fault is indicated, isolate fault in wiring and repair as necessary. Clear continuous memory code 63 and repeat QUICK TEST. If no fault is indicated, go to next step.
17. ECA Connector Test. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connectors and terminals for obvious damage. If connectors and terminals are damaged, repair as necessary. Clear codes and repeat QUICK TEST. If connectors and terminals are okay, fault cannot be duplicated at this time. Clear Continuous Memory Code 63, testing is complete.