2004 Ford taurus

Check PCM fuse first.
Possible failed cam sensor or crank sensor.
Possible failed ignition control module. (most common)

CRANKSHAFT POSITION SENSOR

Description

The crankshaft position (CKP) sensor generates a magnetic pulse signal when the engine is cranking or running. This signal is used by the powertrain control module (PCM) to detect the crankshaft position of each cylinder.

Engine speed is a very important input to the PCM. Crankshaft speed and position are the basis for many calculations made by the computer. Crankshaft position values are transmitted to the computer by pickup coils also known as Permanent Magnet (P/M) generators, Hall Effect sensors or optical sensors. The Crankshaft Position Sensor (CKP) also known as engine speed sensor is typically located in proximity to the crankshaft.

In addition, the PCM uses the CKP sensor in conjunction with the camshaft position sensor to calculate and perform misfire diagnostics.

Testing
1.Connect a scan tool to the data link connector (DLC) and check the crankshaft position (CKP) sensor datastream.
2.The CKP detects engine speed usually between 0 and 6000 rpm. Crank the engine, If there is no pulse signal, or the engine starts but the signal is erratic, perform a visual inspection on the CKP sensor, wiring harness, connector and related components as follows: ◦Ensure that the connector tabs are fully locked
◦Check for corroded terminals
◦Bent pins
◦Pins pulled back in the connector
◦Terminal cavities spread open
◦Harness damage
◦Sensor damage
◦Crankshaft pulley damage

3.If the connectors, wiring harness and related mechanical components pass inspection, perform the following procedures to test the component, wiring and related modules:

Sensor A (3 wire)
A.Disconnect the CKP sensor connector.
B.Check the 12V supply circuit by performing a circuit resistance test between the CKP sensor and PCM. Use the Component Pin Data for circuit details.
C.Check the CKP sensor low signal circuit by performing a circuit resistance test between the CKP sensor and the PCM. Use the Component Pin Data for circuit details.
D.Check the PCM 5V reference signal circuit to the CKP sensor by performing a circuit resistance test between the CKP sensor and the PCM. Use the Component Pin Data for circuit details.

Sensor B (2 wire)
A.Disconnect the CKP sensor connector.
B.Perform a resistance test on the CKP sensor. Use the Component Pin Data for circuit details. If the circuit is open, replace the CKP sensor. Otherwise, proceed to step C.
C.Check the CKP sensor for a short to ground at the sensor housing by performing a circuit resistance test between the sensor pigtail wires and the sensor housing.
D.If there is continuity to the CKP sensor housing, replace the CKP sensor. Otherwise, proceed to step E.
E.Check the reference high signal circuit between the CKP sensor and PCM or ignition control module (ICM) by performing a circuit resistance test. Use the Component Pin Data for circuit details.
F.Check the sensor low signal circuit between the CKP sensor and PCM or ignition control module (ICM) by performing a circuit resistance test. Use the Component Pin Data for circuit details.
G.Repair/replace defective parts as needed and recheck the scan data.