ECU IC 109 Driver

[Vass]

Hey Fellas,

I keep having the driver blow on IC 109 the aircond/fuelpump side after installing an an ECU with a ECMLINK 1 DSM chip (MD165808). Once having a read on here I diagnosed that was what was causing my car not to start I soldered another M5269L in, only for it to blow again a few days later. I went over loom side and couldn't find any shorts/issues, so after reading a bit more i thought it might have something to do with the ECU. So I desoldered the chipset out of my old ECU (MD150427) and installed a socket and put in the chip. Played around with the tuning for a couple of days thinking I had fixed it and it blew again.

A bit more reading on here and the manual and I've gone back into the loom. The only thing I can find is that I get no continuity between the fuel pump and pin 13 or pin 2 on the MFI relay and pin 13. There is no short to ground or too another wire from 13 from testing insitu so I'm thinking its a break or maybe a wire I was meant to swap on install?

I wouldn't think this being the test wire would have anything to do with the driver blowing? The only other thing I can see is MFI relay has signs of getting hot on the number 2 terminal and also on the loom connection it plugs into.

I'd just like your thoughts before I go down another rabbit hole haha


Thanks Guys

 

[Vass]

Update:

I'm pretty sure I've found the issue, i have 126ohms across the 3-7 coil and only 30ohms across the 9-6coil.. i think this extra would be causing the load to blow the driver and the heat found on terminal 2.. i'm just hoping the 126ohms isn't the normal measurement for the 2nd coil.

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[steve]

Extra load in the form of additional resistance doesn't usually cause drivers to blow. It's a lower resistance (like a short) that causes additional current that burns things up.

As you note pin 2 of the MPI relay is the output to the fuel pump. On US ECUs pin 13 is connected to act as a sense line to verify the output from the relay but there are other ECU versions that can to other things with pin 13 depending on how they jumper and strap the circuit board. I don't have either JDM ECUs here so I can't say what they do with pin 13.

Blowing IC 109 is going to be from either the Fuel Pump MPI relay coil shorting or the AC clutch relay. SO either pin 56 or 65 is seeing a intermittent short and blowing the driver IC.

 

[Vass]

Brilliant thank you, I'll go back and check the relays

BTW for other reading maybe down the track, I got someone else to check the resistance on their MPI relay and the 126 was normal, so I was at a standstill with that theory even though it was wrong anyway.

Should I be disconnecting pin 13? I don't remember getting a fuel code 0042 with the old ECU with the OG EPROM but I do now with either of the ECUs with the ECMLink EPROM connected..

 

[barza21]

@Vass ,
Pin 13 on my car is hooked up to the ECU, and as mentioned above, it is used to verify that the fuel pump circuit is providing power to the pump.

In ECMLink, I had disabled the CEL for it for the longest time and it didn't affect the performance of the car. I was able to verify voltage at the pump and at the back of pin 13, and knew everything was good; my issue was a bit fully seated pin that was causing the connection to be intermittent and causing the light to come on.

Unless otherwise noted by some more experienced individuals, I don't think there is any adverse effect to that pin being disconnected other than a check engine light and not knowing if there is truly a fault in that portion of the circuit.