I swapped a 2000 5.3 DBC with Red/Blue connector ecm last year and it ran great. This year I charged the ac and on the first hot day set off the pressure relief valve on the R4 compressor. That’s when I realized that the fans were not coming on with the ac.
I wired the factory low pressure switch in series with a high pressure switch on the compressor. The output goes to the compressor and to C2 pin 17 for ac request. I grounded C2 pin 55 to close the ac circuit.
I rewired the fans using 3 relays as per Ugly Truck Experience so that they both come on low with fan 1 trigger and both on high with fan 2 trigger. I figured this would provide an even draw across the radiator.
The test drive went well, but I noticed that only the 2nd fan was being triggered. Tracing the wires revealed that I mixed up the fan 1 and fan 2 triggers to the relays. I pulled off the connectors and switched the pins. When I try to start it I get a crank, no start. I switched the trigger wires back with the same result.
I’m not getting spark as per a spark tester. I verified that I get power to each coil and verified the grounds for each as well. I have 58 psi at the rail. I installed a new crank position sensor, but it still will not start. Up to this point the engine started every time and ran great.
I’m at a loss where I go from here. Looking for any and all suggestions. Thanks.
I wired the factory low pressure switch in series with a high pressure switch on the compressor. The output goes to the compressor and to C2 pin 17 for ac request. I grounded C2 pin 55 to close the ac circuit.
I rewired the fans using 3 relays as per Ugly Truck Experience so that they both come on low with fan 1 trigger and both on high with fan 2 trigger. I figured this would provide an even draw across the radiator.
The test drive went well, but I noticed that only the 2nd fan was being triggered. Tracing the wires revealed that I mixed up the fan 1 and fan 2 triggers to the relays. I pulled off the connectors and switched the pins. When I try to start it I get a crank, no start. I switched the trigger wires back with the same result.
I’m not getting spark as per a spark tester. I verified that I get power to each coil and verified the grounds for each as well. I have 58 psi at the rail. I installed a new crank position sensor, but it still will not start. Up to this point the engine started every time and ran great.
I’m at a loss where I go from here. Looking for any and all suggestions. Thanks.
