No spark

Hi,

Have you checked the pickup coil in the distributor?

Take a look through this flow chart and let me know if there is anything you missed. The attached pics correlate with the directions.

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1985 Chevy Truck S10/T10 Blazer 4WD V6-173 2.8L
Chart C-4B Ignition System Check (Remote Coil)
Vehicle ALL Diagnostic Trouble Codes ( DTC ) Testing and Inspection Related Tests, Information and Procedures A - E Charts & Related Test Procedures C Charts Chart C-4B Ignition System Check (Remote Coil)
CHART C-4B IGNITION SYSTEM CHECK (REMOTE COIL)
Chart C-4B - Ignition System Check (Remote Coil)

Pic 1

Wiring Diagram for Chart C-4B - Ignition System Check (Remote Coil)

Pic 2


CHART C-4B - IGNITION SYSTEM CHECK (REMOTE COIL)

Test Description:

1. Two wires are checked if there is not spark, because one may be a bad wire.

2. A spark says the problem must be distributor cap or rotor.

3. Normally, there should be battery voltage at the + terminal. Low voltage would indicate an open or high resistance circuit from distributor to coil or ignition switch.

4. Checks for a shorted module or grounded circuit from the ignition coil to the module. The distributor module should be turned "OFF", so normal voltage should be about 12 volts. If the module is turned "ON", the voltage would be low, but above 1 volt. This could cause the ignition coil to fail from excessive heat. With an open ignition coil primary winding, a small amount of voltage will leak through the module from the "Bat." to the tach terminal.


5. Checks for an open module, or circuit to it. 12 volts applied to the module "P" terminal should turn the module "ON" and the voltage should drop to about 7-9 volts.


6. This should turn "OFF" the module and cause a spark. If no spark occurs, the fault is most likely in the ignition coil because most module problems would have been found before this point in the procedure. A module tester could determine which is at fault.

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Note the flow chart is in pic 1. Let me know if this helps.

Take care,
Joe