no spark at coil 2000 bravada
timmys8900
03-04-2009, 05:45 PM
I have changed the ckp the cam pos sens, checked all fuses they all are fine I dont hear the fuel pump turn on it seems like who ever had the truck before me had an electric remote start taken out one yellow wire was cut and i put it back togeather still no spark at the coil i am dumb founded chasing a ghost any ideas was the switch a problem as late as 2000 its a 4.3 litre awd fully loaded
old_master
03-04-2009, 06:53 PM
Testing Fuel Pump Circuits
Remove the fuel pump relay, located in the underhood fuse panel. This will expose the 4 terminals in the fuse panel. Using a volt/ohm meter, probe each terminal to identify the circuits.
The dark green with a white stripe wire should show battery voltage when the ignition is initially turned to the RUN position, (engine off). If the VCM does not receive a signal from the crankshaft position sensor, after 2 to 3 seconds the VCM shuts off the fuel pump relay, and voltage drops to zero on the dark green/white stripe wire. This 2 to 3 second time frame when the fuel pump is on is called "pump prime". The dark green/white stripe wire should show battery voltage continuously when the ignition is in the START position, (the VCM is receiving a signal from the crankshaft position sensor while the engine is cranking). The dark green/white stripe wire comes from the VCM and energizes the coil in the fuel pump relay.
The black wire should be less than 5 ohms resistance to ground. This wire is the ground for the coil in the fuel pump relay.
The gray wire supplies voltage to the fuel pump. It goes directly to the fuel pump connector on the fuel pump module.
The orange wire should show battery voltage at all times. It comes from the ECM B 20amp fuse.
When the dark green/white stripe wire has battery voltage, the contacts in the relay close and connect the orange wire to the grey wire and the fuel pump runs.
The black wire in the fuel pump module connector should show less than 5 ohms resistance to ground. This is the ground for the fuel pump.
Remove the fuel pump relay, located in the underhood fuse panel. This will expose the 4 terminals in the fuse panel. Using a volt/ohm meter, probe each terminal to identify the circuits.
The dark green with a white stripe wire should show battery voltage when the ignition is initially turned to the RUN position, (engine off). If the VCM does not receive a signal from the crankshaft position sensor, after 2 to 3 seconds the VCM shuts off the fuel pump relay, and voltage drops to zero on the dark green/white stripe wire. This 2 to 3 second time frame when the fuel pump is on is called "pump prime". The dark green/white stripe wire should show battery voltage continuously when the ignition is in the START position, (the VCM is receiving a signal from the crankshaft position sensor while the engine is cranking). The dark green/white stripe wire comes from the VCM and energizes the coil in the fuel pump relay.
The black wire should be less than 5 ohms resistance to ground. This wire is the ground for the coil in the fuel pump relay.
The gray wire supplies voltage to the fuel pump. It goes directly to the fuel pump connector on the fuel pump module.
The orange wire should show battery voltage at all times. It comes from the ECM B 20amp fuse.
When the dark green/white stripe wire has battery voltage, the contacts in the relay close and connect the orange wire to the grey wire and the fuel pump runs.
The black wire in the fuel pump module connector should show less than 5 ohms resistance to ground. This is the ground for the fuel pump.
Automotive Network, Inc., Copyright ©2025