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Home › Cadillac › 1996 › Seville SLS › Repair and Diagnosis › Engine Performance › System › Engine Control System - Tests W/Codes › Diagnostic Trouble Codes › DTC P1108 - BARO-To-Map Sensor Circuit Comparison Too High › Diagnostic Procedures

Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) System Check. After performing OBD system check, go to next step.
  2. Start and idle engine. Using scan tool, select ENGINE 1 and note MAP and BARO displays. Subtract MAP value from BARO value. If difference between BARO and MAP value is 11 kPa or less, go to next step. If difference is greater than 11 kPa, fault is not present. Diagnose using DTC P0106 tests.
  3. Connect vacuum gauge at MAP sensor port. With engine at idle, if vacuum is 14 in. Hg or greater, go to next step. If vacuum is less than 14 in. Hg, go to step 14).
  4. Turn engine off. Disconnect MAP sensor harness connector. Turn ignition to LOCK position. Note MAP display on scan tool. If MAP sensor display reads 16 kPa or less, go to next step. If MAP sensor display reads greater than 16 kPa, go to step 7).
  5. Check voltage between ground and MAP sensor ground circuit at MAP sensor harness connector terminal. If voltage is greater than .5 volt, go to step 12). If voltage is less than .5 volt, go to next step.
  6. Store fluid life index as indicated on scan tool. Turn ignition to LOCK position, then disconnect PCM harness connector C1 and MAP sensor harness connector terminals. Using DVOM, check resistance of MAP sensor ground circuit between PCM harness connector and MAP harness connector terminals. If resistance is 5 ohms or less, go to step 11). If resistance is greater than 5 ohms, go to step 9).
  7. Store fluid life index as indicated on scan tool. Turn ignition to LOCK position and wait 30 seconds, then disconnect PCM harness connector C1 and MAP sensor harness connector terminals. Using DVOM, check voltage between chassis ground and MAP sensor ground circuit at MAP sensor harness connector terminal "B". If voltage reading is .5 volt or less, go to step 10). If voltage reading is greater the .5 volt, go to next step).
  8. Repair short to voltage in MAP sensor signal circuit.
  9. Repair open in MAP sensor ground circuit.
  10. Check terminal contact to MAP sensor at PCM harness connector C1. Repair as necessary. If terminal contact is okay, go to step 15).
  11. Repair terminal contact MAP sensor harness connector. Repair as necessary. If terminal contact is okay, go to step 13).
  12. Repair short to voltage in MAP sensor 5-volt reference circuit.
  13. Replace MAP sensor.
  14. Check and repair causes of intake manifold vacuum leaks or low engine vacuum.
  15. Replace PCM. Program replacement PCM using required equipment.
IAT TEMPERATURE-TO-RESISTANCE VALUES

Temperature °F (°C) Ohms
212 (100) 177
194 (90) 241
158 (70) 467
122 (50) 973
104 (40) 1459
86 (30) 2238
68 (20) 3520
50 (10) 5670
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