P081

Powertrain Control Module (PCM) Circuit:

CIRCUIT DESCRIPTION
This diagnostic test checks to see if there are eight 4X reference pulses between CAM signals. When this is not true Code P081 is set. Do not attempt diagnosis or repair unless the customer is experiencing driveability problems associated with this code.

DIAGNOSTIC CIRCUIT CHECK
This Diagnostic Trouble Code (DTC) may set during normal operation. Do not attempt diagnosis or repair unless the customer is experiencing driveability problems associated with this code.

^ 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 630, CKT 632 and CKT 633 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 630, CKT 632 and CKT 633.
3. Intermittent open on CKT 430. CKT 630, CKT 632, and CKT 633 and CKT 739.
4. Poor terminal contact at:
a) Camshaft position sensor terminals "A" and "B."
b) Ignition Control Module (ICM) terminals C2 "A" and "B" or C4 "B" and "C" or C3 "C."
c) Engine compartment fuse block fuse "A13."
5. All four camshaft timing off by one tooth (10° before top dead center).

NOTE: This will be accompanied by other severe driveability symptoms.

TEST CONDITIONS
1. Code P035 not set.
2. Engine speed greater than 496 rpm.
3. Number of CAM pulses since key "ON" is 7 or greater.

FAILURE CONDITIONS
1. Number of 4X reference pulses between CAM pulses is not equal to 8.
2. Failure must exist continuously for 2 or more cycles.

ACTION TAKEN
None.