TEST
ACTION
APPLICABILITY
12
Turn the ignition off.
With the DRBIII
t lab scope probe and the Miller special tool #6801, backprobe the
CKP Signal circuit in the PCM harness connector.
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
Start the engine.
Observe the lab scope screen while wiggling the wiring harness and connectors.
Were there any irregularities in the lab scope pattern?
All
Yes
→ Check the harness connectors carefully. If OK, replace the Crank-
shaft Position Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No
→ Go To 13
13
Turn the ignition off.
With the DRBIII
t lab scope probe and the Miller special tool #6801, backprobe the
CMP Signal circuit in the PCM harness connector.
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
Start the engine.
Observe the lab scope screen while wiggling the wiring harness and connectors.
Were there any irregularities in the lab scope pattern?
All
Yes
→ Check the harness connectors carefully. If OK, replace the Cam-
shaft Position Sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No
→ Go To 14
14
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRBIII
t
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DRBIII
t Freeze Frame information. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?
All
Yes
→ Repair as necessary
Perform POWERTRAIN VERIFICATION TEST VER - 5.
No
→ Test Complete.
172
DRIVEABILITY - SBEC
P1391-INTERMITTENT LOSS OF CMP OR CKP —
Continued