I have a Bosch type 5-pin relay with a built suppression resistor on the coil.
I've read that a resistor is not as efficient as a flyback diode at suppressing voltage spikes when the coil de-energizes.
Can I keep the resistor in place, and add a flyback diode across pins 86 & 85 thereby having both the resistor to dissipate the voltage and the diode to reroute the voltage? Is there any harm to this method?
Thank you everyone for chiming in. I know very little about electrical wiring and I appreciate everyone with more knowledge than me helping me with what I'm trying to do. I'm installing a water methanol injection kit into a turbo charged track car. In the attached diagram, the AEM main controller drives the pump and solenoid that attaches to the injection nozzle to control flow and prevent leakage.
The AEM Failsafe is a computer with a flow sensor that monitors fluid flow. Too high a flow and I could hydro lock the engine, and too low and I could have detonation. Under too high or too flow (alarm conditions) the AEM Failsafe computer will trigger two output signals. The Yellow wire output is +12V output trigger, and the Blue wire is Ground trigger. These triggers can be used to trigger a buzzer, LED light, or to the Engine management to cut turbo boost, etc...
In my application, I intend to use the Yellow trigger wire (+12V) to trigger relay #1 to cut power to the fluid pump. Yellow wire to relay pin 86, pin 85 to vehicle chassis Ground. The relay will run as NC (using pin 87A), only cutting power to the pump when energized (alarm condition).
The Blue trigger wire will trigger Relay #2 to control the solenoid. Since the Blue wire is a Ground wire, I will connect to pin 85 on the relay, pin 86 to +12V. The solenoid positive wire will connect to pin 87A, 30 pin to +12V.
The AEM Failsafe is prone to damage, many user assuming from the yellow and blue trigger wires. That's why I'm trying to use a diode across the relay coil. But the relays I purchased already have a resistor on the coil.
Anyhow, Is my overall diagram kosher???
Thank you everyone :)