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MAJOR electrical issue!

Kenny_Kline

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Joined
Dec 27, 2007
Messages
789
Location
Seekonk, MA
I am having an issue with my ECU not being able to save my tune. I have ruled it out to an electrical issue in my car and believe it is related to another electrical issue I am having.

Basically, when ever I setup my global fuel settings, sensor type, etc. I click copy to ECU. It says it saves. But as soon as you disconnect the battery it goes back to the old settings it had in it from a previous car (I bought the chip used who had a speed density tune) It will copy over his tune/settings, the car runs great but at as soon as I disconnect power, it goes back to old settings. A friend of mine brought his ecu and his chip down today and we tried it out. Sure enough it does the same thing! And his is a running driving car with a known good ecu and chip. So that means my ECU and chip is fine. Can anyone explain this?

Some of you are wondering, why do you keep disconnecting the battery? Well, I have to to cut power off. I will explain. I turn key on, turn key off, take key out but everything stays on (dash lights, blinkers work, etc.) So I start pulling fuses to find out what is keeping it on. The MPI fuse kills the power. I put the fuse back in and the lights arent on sort of like it resets itself. Your probably thinking a bad MPI relay? Yeah I did too so I swapped the MPI relay with 2 other used ones (unknown condition but what are the chances they do the same thing?) I could swap a known good MPI relay as a desperate attempt but I feel I will get the same result based on these findings... I tested MPI relay for power at every pin with key off and only found 1 wire that goes to the battery/MPI fuse. I turn key on, key off, then test again. I am now finding 4 wires inculding the main power wire to have power. SO I start cutting each wire. The last one I cut, shuts off the relay but as soon as I hook the wire back up, dash lights are on. I figure its not an MPI relay issue and possibly a ECY issues because I disconnected the wire again from the MPI relay and its still putting out a 12v signal even with key off when its not supposed to be. If memory serves me correctly, its a white wire with rew stripe or vise versa and it goes back to a pin on the ECU directly according to schematics (I will have to refer to notes to confirm on what pin exactly). I am thinking bad ECU but yet, we just tried my buddies ECU and it does the same thing but doesnt do it in his car.

So with everything said and found, it sounds like a relay not shutting off killing power to ECu but what relay controls the ECU, if any? What further testing can I do? I obviously have an electrical issue in my car that could be related to not being able to save my tune in the ECU. This is just nuts. To add to it, when I hook up the oil pressure wire to sender unit, the oil press spikes to H and stays there even with car off. I disconnect oil press wire and it just lays dead, nothing changes. I pulled gauge fuse and that just shuts off the lights on the dash but MPI relay still has power on all the wires that shouldnt be when key is off.

Its a mess, I know. I feel I am going to have to bring this car down to a known good electrical guy unless someone on here can figure it out or give me other ideas. All I know is this is a mess and this is a problem that is unheard of.

I will do whatever tests are necessary to diagnose.

Discuss!
 

Are you running DS-MAP? If so, the values you are changing aren't stored in the chip, they are in battery backed up RAM of the ECU. You need to make sure the ECU is receiving battery backup on pin #103.
click
As far as your electrical issues, are you sure that someone hasn't miswired a fuelpump rewire? I've seen them already miswired where they create a voltage loop, which feeds battery power back to the MFI accessories. Once the relay pulls in, the loop is created, and the only way to turn it off is to disconnect the battery.
 

Kenny_Kline

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Joined
Dec 27, 2007
Messages
789
Location
Seekonk, MA
Whats DS-MAP? I am running ecmlink v3. I will check for a 12v signal at pin 103 just in case.

The fuel pump has been rewired. I disconnected the fuel pump relay in the trunk to rule that out and it still does it. I will look into wiring a little closer and see what I can turn up. I will post back my findings. Thank you for your advice.
 

Kenny_Kline

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Joined
Dec 27, 2007
Messages
789
Location
Seekonk, MA
ok, not only did i disconnect the fuel pump relay but i removed all grounds, took out sender, unplugged harness... its stripped clean. nothing!

i still get the dash lights. with ecu unplugged, key cycles perfect lights on, lights off. with ecu plugged in, dash lights get stuck on but the ecu is fine
 

Kenny_Kline

Well-known member
Joined
Dec 27, 2007
Messages
789
Location
Seekonk, MA
Ok so here are some findings.

The 24 pin unplug from ECU did not shut off the dash lights. Everything stayed the way it is.

The 18 pin connector from the ECU shut off the dash light when I unplugged it. I plugged it back in and dash lights stayed off so I assume it has something to do with one of these wires. So I start testing them all. Here are the results:

Key on, connector unplugged: I get 8 pins that get power (51, 52, 56, 60, 61, 63, 64, 66)

Key off, connector unplugged: I get 2 pins that get power (63, 66)

Key off, dash lights on, connector plugged in: I get 6 pins that get power (51, 52, 56, 60, 61, 63, 64, 66)

I am going to test the 10 pin and see what turns up. Hopefully this info will help.
 
Last edited:

Kenny_Kline

Well-known member
Joined
Dec 27, 2007
Messages
789
Location
Seekonk, MA
Here are the results of the 10 pin connector. Plugged in, key on, key off dash lights stay on, I unplug 10 pin, dash lights go off, I plug back in, dash lights stay off.

So I move to testing all the pins the same way I did the other one. Here we go..

Key on, 10 pin connector unplugged: 4 pins get power (102, 103, 107, 110)

Key off, 10 pin connector unplugged: 1 pin get power (103)

Key off dash lights on, 10 pin connector plugged in: 5 pins get power (102, 103, 104, 107, 110)

So I notice that pin 104 (nuetral safety switch is getting power) but I am pretty sure this has something to do with the antilag/NLTS funtion in the chip. I cut wire anyways just to be sure and I get no difference so rule out 104 as its just an ECU output of a 12v signal for that feature.
 

The ECMLink v3 doesn't save the settings to flash until you turn the key OFF. Since you are never doing that, the settings never get changed permanently. I ran into that on the bench, and had to call ECMTuning to find out what was going on. The one workaround, which is what I now do on the bench, is to then go into the Direct Access part, and change any cell in an AFR or timing map, and tell it to save it. That forces a flash rewrite, including the changes you made to the Global Fuel, etc.
 

Kenny_Kline

Well-known member
Joined
Dec 27, 2007
Messages
789
Location
Seekonk, MA
Here is an update. I cycle key on then off and dash lights stay on. I cut pin 108 and I get nothing. So I hook it back up. I then move to pin 110. I cut pin 110, about 5 seconds goes buy and it makes a click sound, then lights go off.

But normally when you shut the key to the off position and take key out, lights on dash go out immediatley? They dont stay on for 5 seconds then click off.

Hopefully this helps figure out the problem.
 

Pin #110 is the ignition wire. It sounds like your ignition switch, or something wired into the line from your ignition switch to the ECU, is not turning off. It sounds like its time to pull the switch and test it.
 

Kenny_Kline

Well-known member
Joined
Dec 27, 2007
Messages
789
Location
Seekonk, MA
Pull the switch and test it? Should be fun...

FML

Another person is highly suggesting a grounding issue. It could be both...

I will update this after I have the rest of the week and weekend to work on it.
 

Kenny_Kline

Well-known member
Joined
Dec 27, 2007
Messages
789
Location
Seekonk, MA
Found it. 2 wires were touching (ECU power and MPI power wire) from what looks to be an old remote start wiring job. I was in the process of ripping apart the dash and exposing all the wires to start testing and found deep in the harness, 2 wires that were stripped back and werent covered. They ended up touching and staying connected. I removed them from each other and sure enough, key cycles perfect on and off. It allowed me to save my tune and all. I am going to do a look over of the entire harness and check it all over.

Fun stuff but its all fixed.

Now I just have to finish my fuel system. This damn teflon line/compression fitting is a bitch to hook up!
 
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