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Home >> Isuzu >> 2007 >> i-290 LS, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 86 (Engine Control System & Fuel System - 3.7L - Diagnosis & Troubleshooting) >> Electronic Ignition (EI) System Diagnosis >> Circuit Description

Circuit Description

WARNING: This page is about a different car, the 2007 Isuzu i-370, 2007 GMC Canyon, and 2007 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.

The ignition system uses individual ignition coil/module assemblies for each cylinder. The powertrain control module (PCM) controls the individual coils by transmitting timing pulses on the ignition control (IC) circuit of each ignition coil/module to enable a spark event. The PCM monitors each IC circuit for improper voltage levels. Each ignition coil/module has the following circuits:

Electronic Ignition (EI) System Diagnosis

Step Action Values Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle
2
  1. Turn OFF the ignition.
  2. Remove the fuel pump relay.
  3. Test for spark at each cylinder with a J 26792  Spark Tester.
Did you have spark on all cylinders?		 - Go to Step 3  Go to Step 5 
3 Does the spark tester indicate a bright blue spark on all cylinders? - Go to Step 4  Go to Step 9 
4
  1. Remove the spark plugs.
  2. 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 12 
5
  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the ignition coil/module for the affected cylinder.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp from the ignition voltage circuit to the ground circuit of the ignition coil/module.
Does the test lamp illuminate?		 - Go to Step 7  Go to Step 6 
6 Connect a test lamp from the ignition voltage circuit of the ignition coil/module to a good ground.
Does the test lamp illuminate?		 - Go to Step 11  Go to Step 10 
7
  1. Turn OFF the ignition.
  2. Remove the fuse that supplies ignition voltage to the ignition coil/module.
  3. Measure the resistance of ignition voltage circuit of the ignition coil/module from the fuse to the harness connector of the ignition coil/module with a DMM.
Is the resistance less than the specified value?		 3 Ω Go to Step 8  Go to Step 10 
8 Measure the resistance of ground circuit of the ignition coil/module from the harness connector of the ignition coil assembly to a good ground with a DMM.
Is the resistance less than the specified value?		 3 Ω Go to Step 9  Go to Step 11 
9 Test for an intermittent and for a poor connection at the ignition coil/module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 14  Go to Step 13 
10 Repair the ignition voltage circuit of the ignition coil/module for one of the following conditions:
  • An open
  • A short to ground
  • High resistance

Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 14  -
11 Repair an open or high resistance in the ground circuit of the ignition coil/module. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 14  -
12 Replace the spark plugs. Refer to Spark Plug Replacement .
Did you complete the replacement?		 - Go to Step 14  -
13 Replace the ignition coil/module. Refer to Ignition Coil Replacement .
Did you complete the replacement?		 - Go to Step 14  -
14
  1. Turn the ignition OFF for 30 seconds.
  2. Start the engine and operate the vehicle.
  3. Observe the vehicle performance and driveability.
Does the vehicle operate normally?		 - System OK Go to Step 2 
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