EXPERTEC TSB (416516)

CIRCUIT DESCRIPTION

The PASS-Key II system is designed to disable vehicle operation if the incorrect key or starting procedure is used. The theft deterrent module/CCM enables the crank circuit to the starter and sends a signal to the PCM if the correct key is being used. If the proper signal does not reach the PCM on CKT 229, the PCM will not pulse the injectors "ON" and thus not allow the vehicle to continue to run, even if the crank circuit is bypassed. The proper signal CKT 229 is between 40-60 Hz and is measured using the DC scale on the DVM.

DTC 46 Will Set When: DTC 46 will set and the engine will stall if the proper signal is not being received on CKT 229 by the PCM after 3 seconds.

Action Taken (PCM will default to): DTC 46 will be stored in the PCM memory but will not turn "ON" the Malfunction Indicator Lamp (MIL).

DTC Chart Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. If DTC 46 is stored, and the engine will not crank, it indicates that there is a PASS-Key II problem or an incorrect key or starting procedure is being used.

DIAGNOSTIC AIDS

If the engine starts and then stalls, it indicates that the portion of the theft deterrent module/CCM, which generates the signal to the PCM is not operating or CKT 229 is open or shorted to ground. If theft deterrent module/CCM is found to be OK, as determined from SECTION 8A or 9D, the PCM may be at fault, but this is not a likely condition.

The lock cylinder is bypassed to ground on SEO vehicles, so the ignition key with the resistor pellet is not needed.

CIRCUIT DESCRIPTION

The knock sensor system is used to detect engine detonation. The PCM will retard the spark timing based on signals from the KS module. The knock sensor(s) produces an AC voltage which is sent to the KS module. The amount of AC voltage produced by the sensor(s) is determined by the amount of knock. The circuitry within each knock sensor causes the PCM's 5 volts to be pulled down so that under a no knock condition, CKT 496 would measure about 2.5 volts.

The internal PCM test run on the Knock Sensor (KS) circuit will determine if it is operating correctly.

DTC 43 Will Set When: If the PCM detects that any of the following voltage conditions have been met for 5 seconds, DTC 43 will be set: One of two sensors being open - voltage between about 2.2 volts and 4.1 volts, one sensor being open - voltage greater than 4.1 volts, or sensor(s) grounded - voltage less than.78 volt.

Action Taken (PCM will default to): The Malfunction Indicator Lamp (MIL) will illuminate. The PCM will retard timing to a predetermined maximum based on current RPM and MAP. Some loss of performance may result.

DTC Chart Test Description: Number(s) below refer to circled number(s) on the diagnostic chart.

1. If an audible knock is heard from the engine, repair the internal engine problem, as normally no knock should be detected at idle. The PCM supplies 5 volts on CKT 496 which should be present at the knock sensor terminal(s) when the sensor(s) is disconnected.
2. This test determines if the knock sensor(s) is faulty or if the KS module is faulty.
3. CKT 496 shorted to voltage will set DTC 43 and indicate on Tech 1 as the sensor(s) open. With the sensor(s) and the PCM disconnected, no voltage should be present on CKT 496.
4. An improperly installed knock sensor(s) can prevent the knock sensor(s) from grounding to the block.
5. If a short to battery voltage is found, additional component damage may have occurred.

If DTC 43 resets after the short, it will be necessary to re-run this chart to locate any additional faults.

DIAGNOSTIC AIDS

The PCM has the ability to diagnose opens and shorts in the KS circuit. The Tech 1 will display if one or both sensors are open or if both are grounded when the PCM detects these conditions.

Check CKT 496 for a potential open or short to ground. Also, check for proper installation of the KS module. KS sensor wires routed too closely to secondary ignition components may be susceptible to EMI interference.

Refer to "Intermittents" in "Symptoms," Section "6E3-B".