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motec m150 on mitsubishi evo 8 blowing power fuse

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Hello, I had the vehicle running for 2 years flawlessly.

I decided to change out my old garrett for a 9174 borgwarner and put a turbo speed sensor along with it.

Pin 1 to b06 udig11

Pin 2 to ground a34 0v sensor a

Pin 3 to +5v b26 5v sensor a

Literally right after I enabled this sensor the car starts to blow the ecu fuse(15A) after 5 seconds of starting.

Now I have unplugged the turbospeed sensor

I find out that if I unplug my ACD pump or disable it the car will run flawlessly with the exception of ACD pump not operating.

I also tried to test the ACD pump and found that after running the pump for 10 seconds it'll pop the same ECU fuse(15A)

Initially the pump is controlled through the halfbridge4 via relay, i switched to halfbridge 3 and its the same results. Relay has been confirmed to be fine as I switched to another relay(new) and tested the old relay.

I'm racking my brain on this one after 2 long nights.

I'm kind of down to the pump or ecu. I just don't understand why it would be the pump when all the halfbridge is doing is actuating a relay.

Thank you, any inputs are welcome

Are you sure you have the relay wired correctly? Obviously you are drawing too much current through the half-bridge pin, so I would review that wiring.

Can you put a current clamp on the wires going to the relay to make sure the ECU is not seeing too much current.

If adding the senser was the only change, with no other pins touched, I'd be thinking along the lines of a damaged wire shorting, a faulty relay or, if I had done anything with the relay, a mistake in how I'd refitted the terminals to it?

I could put a amp clamp to the halfbridge wire going to the relay but my assumption is that it would draw too much amperage.

The car wasn't wired up by me unfortunately, it is a ex WRC car and has a beautiful chassis harness in it. My assumption is the relay was wired correctly. Especially since I've been running the vehicle for 2 years without any issues like this.

I triggered the half bridge wire with a power probe (with ecu disconnected) and the pump activated like normal like I can in test mode.

The wires for speed sensor pin 2 and 3 were spliced into the wires though. They were already being used. Not sure if that has anything to do with it. But I now have the speed sensor disabled and disconnected. I only added a pin to the ecu for udig11.

Relay was swapped out with same results.

I double checked the relay fitting and made sure I orientated it the correct way to not damage the terminals at the relay box.

You also swapped your turbo, did you disconnected any grounds from the engine that you could have forgot to put back? Blowing the ECU fuse could be a ground loop problem.

You said it happened when you enabled the turbo speed sensor, so everything was fine and was working with the new turbo setup but the sensor not plugged or enabled?

I'm just trying to trace your step back a little bit, that you could have overlooked something.

If pins 2 & 3 were already being used, obviously you've changed something in the wiring - you need to put that back to EXACTLY how it was before, and checking if it's operating correctly, and THEN try to figure out what they did and how you messed that up.

When you know what the current wiring setup does then, and ONLY then, can you start changing things.

It is currently unplugged and it's doing the same thing.

Forgive my ignorance, but do these sensor a and ground a not just splice to sensors for 5v and sensor ground?

Only you can determine that. Use your multi-meter and check that your new splices only have continuity to the pins you expect. Do you have good documentation on your harness (every pin, splice, wire color, etc?)

Quick update,

After consulting with people here and some good sleep.

We found the wiring to be a little skeptical to the acd pump itself. Seems like it's triggered via normal click relay and the triggered side is only a 20 gauge wire that some how splits to 2 wires on the chassis harness so I assumed it wasn't just controlled via the relay alone. Suspecting it's arcing through the relay as it is the least amount of resistance and it's frying the ecu fuse. So no matter what amp clamp I use on the ecu circuit I couldn't see a high amp situation

Redid all the pump wiring with whatever I had left at the shop in 10 gauge wiring etc. Now the draw is no longer there and car is back running beautifully. It must have been just time and the wiring just didn't like the amperage anymore. Unfortunately I don't have the car fully documented. I have been doing it over the years whenever issues happened.

I'll be redoing the entire engine and chassis harness soon! After diagnosing and checking for this issue I uncovered some other parts I didn't like.

Thank you everyone for your time!

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