Circuit Test B6

Fig 1: MAP/BP Tester Hook-Up

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, or engine condition (valves, vacuum leaks, valve timing, EGR valve, etc.).

1. KOEO Code 22. Code 22 indicates that the MAP/BP sensor is out of Self-Test voltage range (1.4-1.6 volts). Possible causes of this code are:
   • MAP/BP signal circuit open between sensor and ECA.
   • MAP/BP signal circuit shorted to VREF, SIG RTN or ground.
   • Faulty MAP/BP sensor.
   • High atmospheric pressure.
   • Faulty ECA.
   • VREF circuit open at sensor.
   • SIG RTN open at sensor.

   Turn key off. Disconnect MAP/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 illustration. Go to next step.

2. Checking Power to Sensor. 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. VREF Testing. With MAP/BP tester connected, turn key on. Disconnect MAP/BP sensor and repeat step 2). If only Green light comes on, VREF is correct. Replace MAP/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 CIRCUIT TEST A3 , step 1).
4. Tester Output Reading. 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 and go to next step. If output reading is outside range, remove MAP/BP tester and go to step 6).
   NOTE: Measure several known good MAP/BP sensors on available vehicles. Average voltage reading will be typical for your location on date of testing.
   MAP SPECIFICATIONS
   
   

   Elevation (Ft.)	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. Checking Signal Continuity. Turn key off and wait 10 seconds. Disconnect MAP/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 MAP/BP signal at sensor connector and test pin No. 45. If reading is less than 5 ohms, replace ECA. Connect ECA and MAP/BP sensor and repeat QUICK TEST. If reading is 5 ohms or higher, repair opens in wiring. Remove breakout box, connect ECA and MAP/BP sensor. Repeat QUICK TEST.
6. Checking MAP/BP Signal For Shorts. 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 MAP/BP sensor. Set DVOM on 200K-ohm scale. Measure resistance between test pin No. 45 and test pins No. 26, 46, 40, and 60. If any reading is less than 10K ohms, repair shorts in wiring. Remove breakout box and connect ECA and MAP/BP sensor. Repeat QUICK TEST. If all readings are 10K ohms or more, replace MAP/BP sensor. Remove breakout box and connect all wiring. Repeat QUICK TEST.
7. Code 22: Check for EGR Codes. 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. Checking MAP Sensor. Turn key off and wait 10 seconds. Disconnect vacuum hose from MAP sensor. Connect vacuum pump to MAP sensor and apply 18 in. Hg vacuum to sensor. If sensor does not hold vacuum, replace sensor, connect vacuum line and repeat QUICK TEST. If MAP sensor does hold vacuum, release vacuum and go to next step.
9. Eliminating Code 22. Turn key off and wait 10 seconds. Plug vacuum hose going to MAP sensor. Start engine and run at 1400-1600 RPM. Slowly apply 15 in. Hg. vacuum to MAP sensor. With engine under these operating conditions, perform KOER SELF-TEST. Check for Code 22, disregard any other codes at this time. If Code 22 is still present, replace MAP sensor. If Code 22 is no longer displayed, inspect vacuum hose going to MAP sensor. If okay, service other codes at this time. If there are none, check engine for cause of low vacuum.
10. Code 72: Check Vacuum Lines. Code 72 indicates that MAP sensor output did not change enough during dynamic response ("Goose") test. Possible causes for this code are an incorrect MAP sensor vacuum line routing or a faulty MAP sensor. With key on, check vacuum lines for correct routing. Check for disconnections, kinks or blockage. Repair vacuum lines as necessary. If vacuum lines are okay, go to next step.
11. Checking MAP Sensor. Test MAP sensor as described in step 8). If MAP sensor does hold vacuum, release vacuum and go to next step.
12. Checking Vacuum Supply During "Goose" Test. Turn key off, wait 10 seconds. Use a "T" fitting to install a vacuum gauge in the intake manifold MAP sensor supply line. Run the KOER SELF-TEST while observing the vacuum gauge. If vacuum decreased by more than 10 in. Hg during dynamic response ("Goose") test, remove gauge, replace MAP sensor and rerun QUICK TEST. If vacuum did not decrease by 10 in. Hg or more, repair engine mechanical components as necessary to increase engine vacuum.
13. Continuous Code 22: Operating MAP/BP Sensor. Continuous Code 22 indicates the MAP/BP sensor was out of Self-Test range (1.4-1.6 volts) during normal driving conditions. Possible causes for this code are a faulty MAP/BP sensor, faulty wiring harness or connectors, and unusually high or low barometric pressure. In KOEO CONTINUOUS MONITOR TEST mode, observe test equipment while performing the following:
    • Connect a vacuum pump to the MAP/BP sensor.
    • Slowly apply 25 in. Hg vacuum to sensor.
    • Slowly bleed off vacuum from sensor.
    • Lightly tap on sensor (to simulate road shock).
    • "Wiggle" sensor connector.

    If a fault is indicated disconnect sensor and inspect connectors. Repair as necessary. If connectors are okay, replace MAP/BP sensor. If a fault is not indicated, go to next step.

14. Checking Harness. Stay in KOEO 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. Clear codes and repeat QUICK TEST. If no fault is indicated, go to next step.
15. Checking ECA Connector and Harness. 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.