Electronic Ignition (EI) System Diagnosis. Buick LeSabre 2005

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2005 🢒 LeSabre 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Electronic Ignition (EI) System Diagnosis

Circuit Description

The ignition control module (ICM) has independent power and ground circuits. The circuits between the ICM and the powertrain control module (PCM) consists of the following circuits:

•	The ignition control (IC) timing signal

•	The IC timing control

•	The low resolution engine speed signal

•	The medium resolution engine signal

•	The camshaft position signal

•	The low reference

For a complete system description, refer to Electronic Ignition (EI) System Description .

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

Attempt to start the engine.

Does the engine start and run?

Go to Step 5

Go to Step 3

Observe the Engine Speed parameter with a scan tool.
Crank the engine.

Does the scan tool indicate RPM is present?

Go to Step 4

Go to Crankshaft Position Sensor System Diagnosis

Disconnect the ignition control module (ICM) connector.
Jumper each of the following circuits at the connector to each respective mate at the ICM:

•	Pin P ignition 1 voltage

•	Pin K Ground

•	Pin H crankshaft position (CKP) sensor 2 signal

•	Pin N 12-volt reference

•	Pin M low reference

•	Refer to Using Connector Test Adapters in Wiring Systems.

Measure the frequency from the CKP sensor 2 signal circuit at the jumper wire terminal to a good ground with a DMM.
Crank the engine.

Is the frequency more than the specified value?

0 Hz

Go to Step 5

Go to Crankshaft Position Sensor System Diagnosis

Remove the fuel pump relay with the J 43244 Relay Puller Pliers.

Important: Ground the companion cylinder of the cylinder being tested.

Test for spark at each cylinder with a J 26792 Spark Tester.

Did you have spark on any of the cylinders?

Go to Step 6

Go to Step 14

Did you have spark on all of the cylinders?

Go to Step 7

Go to Step 9

Does the spark tester indicate a bright blue spark on all cylinders?

Go to Step 8

Go to Step 9

Remove the spark plugs.
Examine the spark plugs for any abnormal conditions or damage. Refer to Spark Plug Inspection .

Are the spark plugs in good condition?

System OK

Go to Step 15

Turn OFF the ignition.
Connect the J 26792 to the spark plug wire of the inoperative cylinder.
Switch the inoperative spark plug wire connection with a known good cylinder at the ignition coils.
Crank the engine.

Do you have spark on the inoperative cylinder?

Go to Step 12

Go to Step 10

Disconnect the spark plug wires from the inoperative ignition coil.
Measure the secondary resistance of the ignition coil.

Is the resistance within the specified range?

5,000-8,000 ohms

Go to Step 11

Go to Step 17

Remove the inoperative ignition coil.
Connect a test lamp between the control circuits of the ignition coil on the ICM.
Crank the engine.

Does the test lamp turn ON and OFF while the engine is being cranked?

Go to Step 13

Go to Step 14

Test the spark plug wires for the following conditions:

•	Proper routing and correct firing order--Refer to Ignition System Specifications .

•	Arching to ground

•	Proper resistance--Refer to Ignition System Specifications .

Important: If carbon tracking or corrosion is detected, replace both components that are affected.

•	Carbon tracking or corrosion

Did you find and correct the condition?

Go to Step 19

Go to Step 16

Test for an intermittent and for a poor connection at the ignition coil. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 17

Test for an intermittent and for a poor connection at the ICM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 19

Go to Step 18

Replace the spark plugs. Refer to Spark Plug Replacement .

Did you complete the replacement?

Go to Step 19

Replace the spark plug wires. Refer to Spark Plug Wire Replacement .

Did you complete the replacement?

Go to Step 19

Replace the ignition coil. Refer to Ignition Coil Replacement .

Did you complete the replacement?

Go to Step 19

Replace the ICM. Refer to Ignition Control Module Replacement .

Did you complete the replacement?

Go to Step 19

Turn the ignition OFF for 30 seconds.
Start the engine and operate the vehicle.
Observe the vehicle performance and driveability.

Does the vehicle operate normally?

System OK

Go to Step 1