Troubleshooting Hook Signals

A hook signal is generated from the dispenser power supply when a customer would like fuel.  We will need verify dispenser hook signals. Activate each dispenser (not fueling point). You should get 120VAC on the power supply as well as on TB2 channel 1-8 inside the Isotrol controller. 

 

1. Open each dispenser to verify the power supply is distributing 120 VAC. 
   • No voltage at dispenser 
     • Verify ribbon cable to pump control node (PCN) is secure - retest
     • Replace power supply
        
2. Verify each dispenser hook signal is landing on the motor controller.
   • No voltage at motor controller - you will need an electrician. 
   • 120VAC at both the dispenser and motor controller indicates your dispensers are properly calling for fuel, and the motor controller should be activating. 

 

 

 

 

The four STP relays K1-K4 switch the high current Line voltage signals to activate the STP relays for the four grades. If one of the relays is defective the motor controller will not receive a hook signal. 

If the LED for the STP in question illuminates, but there is no 110 VAC on the corresponding lead, this usually indicates shorted or grounded wiring. Ensure to verify both before replacing the power supply.