FixVault

DTC P083: 24X Reference Signal High: Actions

PCM turns on the "SERVICE ENGINE SOON" MIL.

NOTE: Numbers in list refer to circled numbers in diagnostic flow charts, see Fig 1and Fig 2 . For circuit identification see Fig 3.
  1. Checking if Code P035 is set because a REF LO problem can cause other ignition problems.
  2. If the engine stalls, the problem is with crankshaft position "B" sensor because the engine will remain running with only one crankshaft sensor.
  3. Checking crankshaft position "B" sensor and circuitry for opens or shorts. The correct resistance should be between 800 Ohms and 1600 Ohms.
  4. Checking if CKT 1729 or CKT 1730 is shorted to ground. If CKT is shorted to ground it will measure less than 100 Ohms.
  5. If the sensor is able to produce a DC voltage greater than 0.25 volt the sensor is OK.
  6. If engine stalls, the problem is with crankshaft position "A" sensor. If the engine remains running, the ignition control module or CKT 647 are shorted high.
  7. Checking crankshaft position "A" sensor and circuitry for opens or shorts. The correct resistance should be between 800 ohms and 1600 ohms.
  8. Checking if CKT 1727 or CKT 1728 is shorted to ground. If the CKT is shorted to ground it will measure less than 100 ohms.
  9. If the sensor is able to produce a DC voltage greater than 0.25 volt the sensor is OK.
  10. Checking if CKT 647 is shorted high or if the ICM is keeping it high. If you measure greater than 0 Hz the ICM and CKT 647 is OK, the fault is intermittent.
Fig 1: DTC P083: 24X Reference Signal High Flow Chart (1 Of 2)
G00121747Courtesy of GENERAL MOTORS CORP.
Fig 2: DTC P083: 24X Reference Signal High Flow Chart (2 Of 2)
G00121749Courtesy of GENERAL MOTORS CORP.
Fig 3: DTC P083: 24X Reference Signal High Flow Chart Circuit
G00121746Courtesy of GENERAL MOTORS CORP.