Powertrain Controls - ECM/PCM

DTC 83 Chart (1 Of 2):

DTC 83 Chart (2 Of 2):

Ignition System Circuit:

CIRCUIT DESCRIPTION
This diagnostic test checks for 24X signal at a logic high condition. The fault could be induced by the failure of either crankshaft position sensor "A" or "B" input signal to the ignition control module. Under such a condition, the ignition control module would force 24X signal high. This test also checks for 24X shorted to B + externally. If either conditions is met DTC 83 will set.

DTC 83 WILL SET WHEN
24X signal at a logic high and no 24X reference pulses received since last cam pulse.
- Engine speed greater than 496 RPM and less than 1200 RPM.
- Number of cam pulses since key "ON" is 7 or greater.
- Ignition control not in bypass.
- DTC 35 not set.

ACTION TAKEN (PCM WILL DEFAULT TO)
With a current DTC 83 set, PCM will illuminate the Malfunction Indicator Lamp (MIL) (Service Engine Soon).

DTC 83 WILL CLEAR WHEN
The fault no longer exists and the ignition switch is cycled "OFF" and "ON."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. Checking if DTC 35 is set because a REF LO problem can cause other ignition problems.
2. If 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 8OO ohms and 16OO ohms.
4. Checking if CKT 645 or CKT 646 is shorted to ground. If circuit 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 8OO ohms and 16OO ohms.
8. Checking if CKT 573 or CKT 574 is shorted to ground. If the circuit is shorted to ground it will measure less than 1OO 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 1CM is keeping it high If you measure greater than 0 Hz the ICM and CKT 647 is OK, the fault is intermittent.

DIAGNOSTIC AIDS
This DTC may set during normal operation. do not attempt diagnosis or repair unless the customer is experiencing driveability problems associated with this DTC.
This DTC will set with any of the following conditions:

1. Too many cam pulses.
2. Too few cam pulses.
3. Too many 4x pulses.
4. Too few 4x pulses.

These conditions can be caused by the following list of failures:

1. Electromagnetic Interference (EMI) induced on CKT 430, CKT 632, CKT 633 and CKT 630 such as wires run along side spark plug wires or high power transmitters (like mobile radios) operating in the vicinity.
2. Intermittent short to ground/each other on CKT 430, CKT 632, CKT 633 and CKT 630.
3. Intermittent Open on CKT 430, CKT 632, CKT 633 and CKT 630.
4. Poor terminal contact at:
a. Camshaft Position Sensor terminals "A" and "B".
b. Ignition Control Module terminals "C4" "A" AND "B" OR "C1" "B" and "C" OR "C2" "C".
5. All four camshaft timing off by one tooth (100 before top dead center). (Note: this will be accompanied by other severe driveability symptoms).
6. Refer to DTC 83 (part 2 of 2) for further diagnosis of 24X.