Fuel pump trigger not working out of ECU.

[muvro]

Hi all, I’m hoping someone can help.

I’m currently fitting an S15 SR20DET from an australian car into a 510. I’ve gone over and over my wiring to trying to sort a couple of faults. First, the fuel pump relay trigger out of the ECM isn’t working, secondly the Data link isn’t being powered up and won’t communicate with my scanner.

All of the power wires are connected

36 - ignition power (checked)

46,109 - battery power (checked)

38,47 - power from ECM relay (checked)

4 - trigger is operating the ECCM relay.

6,13,39,48,107,108,116 are all earthed.


I’ve gone through the list of wire pin outs at the ECM and checked each wire individually. All of the wires that I can check without the engine running are within spec except for

7 - 12.1v (data link approximately 0.0v)

15 - 0.00v (data link 3-9v)

28 - no wire

106 - flashes 0.7v for a split second and goes to 0.00v (fuel pump relay 0-1.0v for one second after turning ignition on. More than one second after turning ignition on 11-14v) I found I had to move 106 to 104 for a JDM ECU, so I did that and the result is the same.

I have tried to check it with a scan tool, but I’m guessing due to no voltage at the data link, it’s not talking to the scanner.

Are there any other wires that need to be swapped going from ADM to JDM ECU?

Is there a way of checking if the ECU is actually JDM?

Any help would be greatly appreciated. Thank you

[icehouse]

I have 3 or 4 JDM S15 SR ECU's I can snap a pic of each of them when I get home. You can compare the numbers on them.

The pinout above looks like the JDM pinout to me. All the pins line up to what I've done.

You're low side switching the pump relay right? If you accidently power it the ecu will burnout. Amazingly it will still run you will just have to run the fuel pump without the ecu.

[muvro]

Thanks for the quick reply.

I’ve copied the wiring of the original fuel pump relay. It has black/yellow wire on the other side of the trigger, which is powered if I recall. I will double check when I get into work.

What does low side switching mean?

Some photos of the ECMs would be great. Can’t find anything concrete on google.

[muvro]

Bit of an update, I found that I had hooked up the green wire from the Data link plug to the exact same colored wire on the ECM. This is wrong, it was meant to go to switched ignition. It’s now done and the scanner works. Through the scanner, I can operate the fuel pump, so the wiring seems to be correct.

Any ideas, why the pumps won’t operate under normal ignition on state?

Is there some sort of security or safety thing that cuts the fuel pump?

[icehouse]

I totally forgot to take those pics. Seems like you got that part sorted. Wow that scanner tool sounds rad!!! Can you see the timing map?

The fuel pump usally primes for 1 second while key is turned on then always runs when the engine is turning. If the key is on and the engine is not running the fuel pump is off. I've heard its a saftey thing.

[bertvorgon]

Yes, it is a safety issue in the event of a crash.

I know on my Ford Aerostar that the fuel pump would run for 10 seconds and if the engine saw NO oil pressure, the pump would shut off.

All vehicles have this function as in most crashes the engine goes off and you do not want the fuel pump to keep running in case a fuel line is severed.

[510rob]

I know Ford cars also have an inertia switch in the fuel pump circuit, as does my motorcycle. I assume all modern vehicles have something similar...

scroll down for a nice cut-away to get the idea...

https://www.ford-trucks.com/forums/1457 ... ion-2.html