Canyon, Colorado 2004-2005

Diagnosis & Testing

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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: An ignition voltage circuit, A ground and an IC circuit.

If the problem is intermittent, inspect the following:



Wiring broken inside the insulation
 
Poor connection between the male and female terminal at a connector
 
Poor terminal to wire connection; Some conditions which fall under this description are poor crimps, poor solder joints, crimping over the wire insulation rather than the wire itself, and corrosion in the wire to terminal contact area, etc.
 
Pierced or damaged insulation can allow moisture to enter the wiring causing corrosion. The conductor can corrode inside the insulation, with little visible evidence. Look for swollen and stiff sections of wire in the suspect circuits
 
Wiring which has been pinched, cut, or its insulation rubbed through may cause an intermittent open or short as the bare area touches other wiring or parts of the vehicle
 
Wiring that comes in contact with hot or exhaust components
 

Flat Wire (Dock & Lock) Connectors



There are no serviceable parts for flat wire (dock and lock) connectors on the harness side or the component side. Perform the following procedure in order to test terminal contact:



Remove the component in question
 
Visually inspect each side of the connector for signs of contamination. Avoid touching either side of the connector as oil from your skin may be a source of contamination as well
 
Visually inspect the terminal bearing surfaces of the flat wire circuits for splits, cracks, or other imperfections that could cause poor terminal contact. Visually inspect the component side connector to ensure that all of the terminals are uniform and free of damage or deformation
 
Insert the appropriate adapter from the on the flat wire harness connector in order to test the circuit in question
 

Testing For Proper Terminal Contact In Bussed Electrical Centers (BEC)




NOTE
It is very important to use the correct test adapter when testing for proper terminal contact of fuses and relays in a bussed electrical center (BEC). Use J-35616-35 to test for proper terminal contact. Failure to use J-35616-35 can result in improper diagnosis of the BEC.

Perform the following in order to test terminal contact:



Separate the connector halves
 
Visually inspect the connector halves for contamination. Contamination may result in a white or green build-up within the connector body or between terminals. This causes high terminal resistance, intermittent contact, or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals, and connector body
 
Using an equivalent male terminal from the J-38125 , test that the retention force is significantly different between a good terminal and a suspect terminal. Replace the female terminal in question
 

 
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