Wiring relay to use a negative trigger?.

[mattymc 30]

I am in the process of wiring a haltech into my Ed and I can't figure out how to wire the fuel pump relay.

 

The haltech grounds to activate the relay but I have tried everything and I can not get it to run the fuel pump. So I guess my question is, how do you wire up a relay to turn on when the wire on the haltech grounds it?.

 

It is the only thing I need to finish off and it's driving me nuts.

 

Can any electrical guru's shed some light?.

 

Cheers

[n00bus m@x1mus 465]

Hard wire the pump to earth then send the pos side of the pump to the 30 pin on the relay. Then from thr 87 pin thru a fuse then to the pos post on battery. 86 pin to ignition switch and 85 pin to the haltech.

[Crazy2287 1,886]

The same positive, usually via the ignition relay, that provides 12v to the haltech is the one you need to use for the positive on the coil in the relay. The other side of the relay coil goes to the haltech trigger.

 

This is usually important, The same 12V that supply the haltech, Needs to supply the 12v side of the relay coil. The other leg for the relay coil goes to the negitive trigger from the haltech.

[gerg 10,871]

Assuming that the Haltech only grounds out that circuit when it's powered up and running, you could just run a single, large fused wire from battery straight to the 30 terminal on the relay, then loop a small wire over to 85. Run 86 back to the Haltech earth trigger and 87 to your pump. No need to run an ignition wire as well, as the Haltech will tell the fuel pump when to run anyway.

[mattymc 30]

Thanks heaps fella's. I can see a few areas where I could have gone wrong. The haltech has it's own relay so if I run the power for the fuel pump relay from the haltech relay that might solve the issue.

 

Also in regards to hard wiring the fuel pump. I have run a new wire from the pump relay to the + of the fuel pump connector. I have not touched the earth wire to the pump. Can I just ground the wire from the fuel pump to the chassis?.

[n00bus m@x1mus 465]

Yes you can, but make sure its a clean connection that wont corrode from vapour exposure.

[mattymc 30]

Yes you can, but make sure its a clean connection that wont corrode from vapour exposure.

Awesome I will give that a crack tomorrow.

[mattymc 30]

I have tried all of the above and still no go. Now when the haltech is plugged in smartlock goes crazy and wont allow the car to crank. I think that I have an earth problem somewhere. I will have a look over all the wiring again tomorrow. One interesting thing is that the trigger wire for the haltech which should be a ground is getting 5 volts.

 

Tomorrow is another day I guess 

[Crazy2287 1,886]

Assuming that the Haltech only grounds out that circuit when it's powered up and running, you could just run a single, large fused wire from battery straight to the 30 terminal on the relay, then loop a small wire over to 85. Run 86 back to the Haltech earth trigger and 87 to your pump. No need to run an ignition wire as well, as the Haltech will tell the fuel pump when to run anyway.

Be careful with this, On some ECU's wiring this way causes 12v to travel through the relay and power on circuits within the ECU. Not familiar with the inner workings of haltech but This is a reason why it needs to be a IGN switched 12v supply on some ECU's.

[Crazy2287 1,886]

Thanks heaps fella's. I can see a few areas where I could have gone wrong. The haltech has it's own relay so if I run the power for the fuel pump relay from the haltech relay that might solve the issue.

By power do you mean the relay coils power or the switched power?

Study this pic, Note the diagram etched into the body of the relay. The box is the relay coil. The relay switch should get power from a strong supply, depending on the fuel pump you are using you can expect from 5amps right up to 30amps. When i did my ECU i had a 10awg wire running to a distro box which is then fused to each ancillary, ign, injectors, EGO sensor, fuel pump relay and the ECU relay ect.

 

[mattymc 30]

By power do you mean the relay coils power or the switched power?

Study this pic, Note the diagram etched into the body of the relay. The box is the relay coil. The relay switch should get power from a strong supply, depending on the fuel pump you are using you can expect from 5amps right up to 30amps. When i did my ECU i had a 10awg wire running to a distro box which is then fused to each ancillary, ign, injectors, EGO sensor, fuel pump relay and the ECU relay ect.

 

When I say power I have taken power strait from the battery via a fuse. I also have a switched 12v. I have researched relays and understand the pins but clearly I have missed something. I am running the factory fuel pump via a new relay. Possibly the way I am wiring things is not working with the factory wiring.

 

Sorry if my questions sound dumb but I have been trying to sort this for ages. Electrical work is not my strong point but I have learnt heaps as I have progressed with this install. Thanks for your patience everyone.

 

Below is a picture of how the haltech manual illustrates the fuel pump wiring.

 

[gerg 10,871]

Relays can be a headfuck. There are so many combinations you can use just with one type, and there are many. The pin positions/numbers can vary even with the standard "horn relay" pin layout. The numbers always stay the same for the given function though:

 

30: supply (batt)

85: trigger in

86: earth

87: switched output (normally open)

87a: sometimes it's a second NO output terminal, otherwise (if it's a changeover relay) it's a "normally closed" output: ie it puts out power when the relay is off.

The relays often have a circuit diagram on the side of them so there's no confusion as to what they are.

 

Crazy I know nothing about Haltechs, so if you reckon it could get power via a backfeed through that earth trigger, I believe you.

[mattymc 30]

After a complete rewire of my injectors and sensors the car runs. The gas injection was interfering with things. I am using the factory ecu fuel pump relay right now but will try wire the haltech to control that as well. Thanks for all of the input and advice.