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Test H - BP Sensor

NOTE: Barometric pressure sensor output is digital and must be measured with MAP/BP tester.

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: unusually high/low atmospheric barometer reading, kinked or blocked vacuum lines, engine condition (valves, vacuum leaks, valve timing, EGR valve, etc.).

  1. Code 22 Displayed, Engine Off. Turn key off. Disconnect BP sensor from harness. Connect MAP/BP tester between wiring harness and MAP/BP sensor. Connect banana plugs of tester into DVOM and set DVOM on 20-volt scale. See MAP/BP  Tester Hook-Up. Go to next step.
    Fig 1: MAP/BP Tester Hook-Up
    G2547
  2. With MAP/BP tester connected, turn key on. If only Green light on tester is lit, VREF is correct. Go to step 4). If "LESS THAN 4 VOLTS" Red light or no lights come on, VREF is too low. If "MORE THAN 6 VOLTS" Red light comes on, VREF is too high. If VREF is too high or too low, go to next step.
  3. With MAP/BP tester connected, turn key on. Disconnect BP sensor and repeat step 2). If only Green light comes on, VREF is correct. Replace BP sensor and repeat QUICK TEST  . If "LESS THAN 4 VOLTS" Red light or no lights come on, VREF is too low. If "MORE THAN 6 VOLTS" Red light comes on, VREF is too high. If VREF is too high or too low, remove MAP/BP tester, connect sensor, then go to TEST C - REFERENCE VOLTAGE  , step 1).
  4. With MAP/BP tester connected and key on, measure sensor output voltage. If voltage output is in correct range for altitude of vehicle being tested, remove MAP/BP tester. Go to next step. If output reading is outside range, remove MAP/BP tester and go to step 6).
    NOTE: Measure several known good BP sensors on available vehicles. Mean voltage reading will be typical for your location on date of testing.
    BAROMETRIC PRESSURE VOLTAGE OUTPUT

    Elevation (Ft.) Voltage Output (Volts)
    0 1.55-1.63
    1000 1.52-1.60
    2000 1.49-1.57
    3000 1.46-1.54
    4000 1.43-1.51
    5000 1.40-1.48
    6000 1.37-1.45
    7000 1.35-1.43
  5. Turn key off and wait 10 seconds. Disconnect BP sensor from harness. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between BP signal at sensor connector and test pin No. 45. If reading is less than 5 ohms, replace ECA. Connect ECA and BP sensor. Repeat QUICK TEST  . If reading is 5 ohms or higher, repair opens in wiring. Remove breakout box, connect ECA and BP sensor. Repeat QUICK TEST  .
  6. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Disconnect harness at BP sensor. Set DVOM on 200,000-ohm scale. Measure resistance between test pin No. 45 and test pins No. 26, 46, 40, and 60. If any reading is less than 10,000 ohms, repair shorts in wiring. Remove breakout box and connect ECA and BP sensor. Repeat QUICK TEST  . If all readings are 10,000 ohms or more, replace BP sensor. Remove breakout box and connect all wiring. Repeat QUICK TEST  .
  7. Code 22 Displayed, KEY ON/ENGINE RUNNING (KOER) . Check to see if service codes 31, 32, 33, 34 or 35 are present. If so, go to KOER SELF-TEST table and perform appropriate CIRCUIT TEST  . If not, go to next step.
  8. Turn key off. Disconnect BP sensor from harness. Connect MAP/BP tester between wiring harness and BP sensor. Connect banana plugs of tester into DVOM and set DVOM on 20-volt scale. See MAP/BP  Tester Hook-Up. Go to next step.
  9. Turn key on and measure sensor output. Compare values to BAROMETRIC PRESSURE VOLTAGE OUTPUT  table. If reading is within range, go to DIAGNOSIS BY SYMPTOM TEST  on the 1.9L EFI. If reading is within range on all other engines, go to next step. If reading is out of range, replace BP sensor. Repeat QUICK TEST  .
  10. Stay in CONTINUOUS MONITOR (WIGGLE) TEST. Observe VOM or diagnostic tester for indication of fault while shaking, bending or wiggling small sections of harness from sensor connector to firewall. Check harness from firewall to ECA in same manner. If fault is indicated, isolate fault in harness and repair as necessary. Repeat QUICK TEST  . If no fault is indicated, go to next step.
  11. 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 not okay, repair as necessary. Repeat QUICK TEST  . If connectors and terminals are okay, fault cannot be duplicated at this time. Continuous code 22 testing is complete.
Fig 2: Barometric Pressure Sensor Circuit
G2548
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