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Discussion Starter · #1 · (Edited)

Hyundai Santa Fe 2.4 Petrol.

I have a fault that means that the relay does not operate so I have had to by pass with a full earth ...

See picture....

Does anyone have any suggetions what I can test or where I can look to resolve the problem properly?

Battery shows a full good earth (battery earth to chasis) - ECM has good earth (cheched with previous problem)- I have the same problem with either of 2 different ECM's connected.



843 Posts
Hi Jon,
I understand the relay does not get a controlled ground signal from the ECM, in fact 2 ECM's, you hooked up.
I cannot imagine both ECM's are defective so you could measure the ECM outgoing ground signal at the ECM connector, being pin 24. It could be the wiring going to the relay is faulty.
However, the ECM should get its command to switch the relay by ignition key voltage.
Does the engine run normally after you've bypassed the ground line to the relay?
Furthermore the ECM controls the relay also by a signal from the fuel pressure sensor.
It should switch on the pump at ignition key to contact until fuel pressure is reached. Then the pump is switched off again until you crank the engine to start. So could it be the ECM simply is getting a fuel pressure reached signal from the fuel pressure sensor, so it will not see the need to switch on the fuel pump?
You could check the fuel pressure sensor for correct function, maybe by measuring it's signal when you activate the pump by activating the relay.
Otherwise you could check the outgoing control wire from the ECM to the relay.
Several possibilities.
Good luck,
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